SUMMARY OF THE LESSON ON DRAWING USING ICT
Lesson topic: Graphic work No. 6 "Drawing of the part with the necessary cut"
Lesson Objectives:
consolidate knowledge, skills and abilities in drawing drawings using cuts; develop spatial representations and spatial thinking; create a graphic culture.
Lesson type: combined.
Lesson equipment: posters, handouts, multimedia projector, computers, screen
Literature:
b) capital letters of the Russian alphabet.
5. If the rendered section is symmetrical and is located on the continuation of the cutting plane, then the cutting plane and the corresponding section:
a) designate;
b) do not indicate
Student responses: 1-a; 2-a; 3-b; 4-b; 5 B
(Slide number 3) Task 2: Find errors in the designation of sections
Answer: 2 sections are not marked: A-A and B-B
Task 3: What types of incisions do you know?
Answer: the teacher summarizes the students' answers using Slide 4
Question to the class: On what basis can these graphic images be divided?
Answer: By the number of cutting planes into two groups.
Question to the class: That is, the basis for classification is the number of cutting planes. And what is the classification: simple or complex?
Answer: A simple classification, since the basis for the classification is one.
(Slide number 5) Task 4: Fill in the table "Location of cuts"
Answer:(Slide number 6)
III. Explanation of new material (7-10 min)
1. Formation of a frontal incision (Slide No. 7)
2. Formation of a profile cut. (Slide number 8)
3. Formation of a horizontal cut (Slide No. 9)
Teacher's explanation: Those cuts that are made using one secant plane are called simple, and those that are made using 2 or more planes are called complex. Consider simple cuts. To describe the position of the cutting plane, it is considered in relation to the horizontal projection plane
Question to the class: How is the cutting plane located relative to the horizontal plane of symmetry?
Answer: It is parallel to the horizontal projection plane.
Teacher's explanation. Such cuts are called horizontal cuts. If the cutting plane is perpendicular to the horizontal plane, then such cuts are called vertical. Post a drawing of a vertical section on the board. If the cutting plane is located at an angle to the horizontal plane of projections, then such cuts are called (at this stage of the lesson, students already guess what the proposed cuts will be called, and with the help of the teacher give names to the cuts) ... oblique. Place a drawing of an oblique cut on the board. Two cases of a vertical cut are considered separately. Place the drawings of the frontal and profile sections on the board. For them, also determine the position of the cutting plane relative to the frontal and profile planes of projections.
Question to the class:
Answer: Frontal and profile sections.
Question to the class: What is the name of each of these cuts?
Answer: Frontal and profile sections
1. Derivation of the algorithm for constructing a section (Slides No. 10-13)
Gymnastics for the eyes:
1. close your eyes;
2. blink;
3. look out the window, look at the board, look out the window again.
We continue to work.
IV. Graphic work (15-20 min)
Explanation of the stages of performing graphic work (Slide No. 14)
Open the file in the folder using the Paint editor. Choose the appropriate line thickness and follow the algorithm.
Algorithm for constructing a section.
1. Analysis of the geometric shape of the object.
2. Determining the position of the cutting plane.
3. Mental representation of the figure of the section.
4. Removal of visible contour lines related to the removed part.
5. Transfer of lines of an invisible contour to visible ones.
6. Outline the outline of the section figure, hatch, mark the section.
Create a folder, name it with your last names, and save the results to your folder.
V.Completion of the lesson, issuance of homework (2 min)
Teacher: Open your diaries, write down the homework (Slide No. 15)
2. task! 3 - Fig. 195 (a, b) p. 150
(Explanation of homework).
Teacher: What questions about the lesson and homework do you have?
Thank you for your work. The lesson is over.
TO GAOU SPO "Pedagogical College of Tambov" METHODOLOGICAL INSTRUCTIONS for the implementation of practical work of the discipline "Engineering graphics" for students of the specialty "280707 Protection in emergency situations, rescue technician" (Works No. 1-6) TAMBOV, 2013 Author: TARASOV V.E., teacher of special disciplines TO GAOU SPO "Pedagogical College of Tambov" Reviewer: Lappa T.I. Engineering graphics" for students of the specialty "280707 Protection in emergency situations, rescue technician" (Works No. 1-6) Guidelines for the implementation of graphic works in the course "Engineering graphics" is intended for students of the specialty 280707 "Protection in emergency situations". The manual contains the necessary theoretical and reference material for the implementation of graphic works No. 1-6. Recommended by the scientific and methodological council of the college as a teaching aid. INTRODUCTION The program of the course "Engineering Graphics" for students majoring in secondary vocational education 280707 Protection in emergency situations, a rescue technician determines the amount of knowledge necessary to complete engineering drawings and diagrams. Students perform most of the work on their own, therefore, when studying the course of engineering graphics, they are recommended to familiarize themselves with the requirements set by the ESKD standards for the execution of drawings. All graphic works by students must be performed in accordance with their version by serial number in the educational journal. The purpose of this publication is to familiarize students with fonts, lines, methods for constructing interfaces, depicting objects, arranging views, making cuts, sections and axonometric projections, applying dimensions and maximum deviations, graphic designation of materials in graphic works and drawing electrical circuits. REQUIREMENTS FOR THE IMPLEMENTATION OF GRAPHIC TASKS BY THE ESKD STANDARDS The Unified Design Documentation System (ESKD) is the most important system of permanent technical and organizational requirements that ensure the interchange of design documentation without its re-registration between industries and individual enterprises. It makes it possible to ensure the expansion of unification in the design development of projects for industrial products; simplification of document forms and reduction of their nomenclature, as well as graphic images: mechanized and automated creation of documentation and, most importantly, the readiness of industry to organize the production of any product at any enterprise in the shortest possible time. ESKD presents a set of state standards that establish interconnected uniform rules and regulations on the procedure for the development and circulation of design documentation used by various organizations and enterprises. These unified rules also apply to educational documentation, which includes graphic tasks performed by students, so all images must be made clearly, accurately and in accordance with the requirements of ESKD. Tasks are performed on sheets of A3 and A4 drawing paper (GOST 2.301-68). After drawing the frame on the sheet in the lower right corner, the dimensions of the main inscription of the task are outlined, which is the same for all formats. The form of the main inscription is adopted in accordance with the requirements of GOST 2.104-68. Images must be performed on the scale specified in the task, but observing GOST 2.302-68. When filling in the main and other inscriptions, it is required to comply with the requirements of GOST 2.304-81. When applying dimensions, it is recommended to use GOST 2.307-68. When tracing the image, the thickness of the main lines should be taken as 0.8 - 1.0 mm, and the thickness of the remaining lines - in accordance with GOST 2.303-68. LIST OF USED LITERATURE 1. Bogolyubov S. K. Engineering graphics. - M.: Mashinostroenie, 2004. -352s 2. GOST 2. 303-68. Lines. 3. GOST 2. 304-81. Drawing fonts. 4. GOST 2. 305-68. Images - types, cuts, sections. 5. GOST 2. 301-68. Formats // ESKD. General rules for the execution of drawings. GOST 22.301-68 - GOST 2.321-84. M., 1988. 239 p. 6. GOST 2. 302-68. Scales. 7. GOST 2. 307-68. Application of dimensions and limit deviations. 8. Levitsky V.S. Engineering drawing / V.S. Levitsky. M., 1998. 383 p. 9. Engineering drawing / G.P. Vyatkin, A.N. Andreeva, A.K. Boltukhin et al. M., 1985. 368 p. 10. Popova G.N. Mechanical engineering drawing / G.N. Popova, S.Yu. Alekseev. St. Petersburg, 1999. 453 p. 11. S. K. Bogolyubov Individual assignments for the course of drawing: Prakt. Handbook for students of technical schools. - M.: Higher. school, 1989 - 368 p.: ill. 12. Fedorenko V.A. Handbook of engineering drawing / V.A. Fedorenko, A.I. Shoshin. L., 1986. 416 p. PRACTICAL WORK No. 1 DRAWING THE FORMAT AND THE MAIN INscription FOR GRAPHIC AND TEXT DOCUMENTS The purpose of the work: to study graphic formats, types of main inscriptions in the drawings All drawings should be made on sheets of paper of a standard size. The formats of the sheets of paper are determined by the dimensions of the outer frame of the drawing (Fig. 3). It is drawn with a solid thin line. The drawing frame line is drawn as a solid thick main line at a distance of 5 mm from the outer frame. Leave a margin of 20 mm on the left for filing. The designation and dimensions of the sides of the formats are established by GOST 2.304-68. Data on the main formats are given in table. 1. Table 1 Designation of the format Dimensions of the sides of the format, mm А0841х1189А1594х841А2420х594А3297х420А4210х297 RULES AND PROCEDURES FOR PERFORMING THE WORK Work is performed in pencil on a sheet of A3 (297x420) or A4 (210x297) format in accordance with the given sample. The drawing is drawn up with an internal frame (in the form of a solid main line), from the borders of the format on the left side leave a margin for stitching 20mm, on all other sides - 5mm. In the lower right corner of the drawing, the main inscription (stamp) is drawn in accordance with GOST 2.104-68 * in accordance with Figure 1. The following filling in the columns of the main inscription in the conditions of the educational process is recommended (the standard designation of the graph is saved): column 1 - the name of the part or assembly unit (name topic on which the task was completed); column 2 - the designation of the document according to the system adopted in the college (name of the group, year, number according to the list, number of the work performed - ЗЧС.31.2011.05.02.); column 3 - designation of the material of the part (filled in only on the drawings of the parts); column 4 - do not fill out; column 5 - mass of the product (do not fill out); column 6 - image scale (in accordance with GOST 2.302-68* and GOST 2.109-73); column 7 - the serial number of the sheet (on documents consisting of one sheet, the column is not filled out); column 8 - the total number of sheets of the document (the column is filled out only on the first sheet of the document); column 9 - the name of the educational institution and the number of the group; column 10 - the nature of the work performed by the person signing the document, for example: Developed by: (student) Checked by: (teacher) column 11 - clear spelling of the names of the persons who signed the document; column 12 - signatures of persons whose names are indicated in column 11; column 13 - the date of signing the document (the month and year are indicated). Fig. 1 The text on the drawing field and in the main inscription is made in 3.5, 5 or 7 mm font, and the dimensional numbers are 3.5 or 5 mm. An example of filling in the main inscription is given in Figure 2. The work is done in thin lines, then the final outline of the drawing is made with lines in accordance with their purpose. The stroke begins with the drawing of dash-dotted and solid thin lines, then the main solid lines are outlined: first the curved sections, then the straight lines. TASK: on a sheet of A4 drawing paper, draw the lines of the drawing frame and the title block. PRACTICAL WORK № 2 IMPLEMENTATION OF THE DRAWING FONT Purpose of the work: To study the pits of drawing fonts, to gain skills in writing in a drawing font. GOST 2.304-81 establishes drawing fonts applied to drawings and other technical documents of all industries and construction. The font size defines the height h of the capital letters in mm. The thickness of the font line d depends on the type and height of the font. GOST sets the following font sizes: (1.8); 2.5; 3.5; 5; 7; ten; fourteen; 20 (Tables 1, 2). The use of font 1.8 is not recommended and is only allowed for type B. The following types of font are installed: Type A with an inclination of 75 ° - d = (1/14) h; Type A without slope - d = (1/14)h; Type B with a slope of 75° - d = (1/10)h; Type B without slope - d = (1/10)h. Font parameters are given in tables 1 and 2. Table 1 - Font parameters, mm 05,07,07,01010Letter spacinga0,50,70,71,01,01,41,42,022,8Minimum line spacingb5,56,08,08,511,012,016,017,02224Minimum word spacinge1,52,12,13,03,04,24 ,26,06,08,4 Thickness of font lines d0,250,350,350,50,50,70,71,01,01,4 V, I, Y, K, L, N, O, P, R, T, U, C, H, L, E, I Щ, b8d345.5812Е, Г, З, С5d1.82.53.557 Lowercase letters A, b, c, d, e, e, h, i, d, k, l, n, o, p, p, y, x, h , c, b, e, ya 523446d23469 JOB. In font size 10 type B, write the depicted letters of the alphabet (lowercase and uppercase), numbers from 0 to 10 and any two words. A sample of the task is shown in Figure 1. INSTRUCTIONS FOR COMPLETING THE JOB First you need to prepare a sheet of standard A4 paper with a frame at a distance of 5 mm from the edges on the top, right and bottom and 20 mm on the left. The sequence of the task for writing a standard font type B size 10 is as follows: - draw all the auxiliary horizontal straight lines that define the boundaries of the lines of the font; - postpone the distance between the lines, equal to 15 mm; - postpone the height of the font h, i.e. 10 mm; - set aside segments equal to the width of the letters plus the distance between the letters; - draw inclined lines for the grid at an angle of 75 ° using two triangles: with an angle of 45 ° and with angles of 30 ° and 60 °. An example of completing a task PRACTICAL WORK No. 3 DRAWING LINES Purpose of work: gaining skills in drawing lines and using drawing tools All drawings are made with lines for various purposes, styles and thicknesses (table 3). The thickness of the lines depends on the size, complexity and purpose of the drawing. According to GOST 2.303-68, lines of various types are used to depict products in drawings, depending on their purpose, which helps to identify the shape of the depicted product. Table 1 - Types of lines Style Line thickness in relation to the thickness of the main line Name Applications A solid thick main line is made with a thickness indicated by the letter s, ranging from 0.5 to 1.4 mm, depending on the complexity and size of the image in this drawing, as well as on the format drawing. A solid thick line is used to depict the visible contour of an object, the outline of a section that is taken out, and the contour that is part of the section. s/3-s/2 A solid thin line is used to depict dimension and extension lines, section hatching, a superimposed section contour line, leader lines, lines for depicting border details ("furnishings"). s/3-s/2 A solid wavy line is used for drawing break lines, the line of demarcation of the view and section s/3-s/2 A dashed line is used to represent an invisible contour. The length of the strokes must be the same. The length should be chosen, depending on the size of the image, from about 2 to 8 mm, the distance between the strokes is 1 ... 2 mm. for superimposed or extended sections. The length of the strokes must be the same and is selected depending on the size of the image, from about 5 to 30 mm. The distance between the strokes is recommended to be taken 2 ... 3 mm. -s/2 An open line is used to indicate a section line. The length of the strokes is taken 8 ... 20 mm, depending on the size of the image. s / 3-s / 2 A solid thin line with breaks is used for long break lines. s / 3-s / 2 intermediate positions; fold lines on reamers The quality of a drawing largely depends on the quality and adjustment of tools, as well as on their care. Drawing tools and accessories must be kept in good working order. After work, the tools should be wiped and stored in a dry place. This prevents warping of wooden instruments and corrosion of metal ones. Before work, wash your hands and wipe the squares and the T-square with a soft rubber band. The pencils. The accuracy and accuracy of the drawing largely depend on the correct sharpening of the pencil. Graphite can be sharpened with a sandpaper. The student must have three grades of pencil: M-B, TM-HB and T-H. When making drawings with thin lines, it is recommended to use a T grade pencil. Draw the lines of the drawing with a TM or M pencil. Insert an M grade lead into the compass. A circular compass is used to draw circles. A needle is inserted into one leg of the compass and secured with a screw, and a pencil insert into the other. To measure the dimensions and put them on the drawing, an insert with a needle is used. The caliper is used for drawing circles of small diameter (from 0.5 to 10 mm). The rotating leg for ease of use moves freely along the axis of the caliper. When drawing circles of large radii, an extension cord is inserted into the leg of the compass in which the pencil insert is fixed. Lines are drawn in a certain direction: Horizontal lines are drawn from left to right, vertical lines are drawn from bottom to top, circles and curves are drawn clockwise. The center of the circle must necessarily be at the intersection of the strokes of the axial and center lines. Hatching in the drawings is performed in the form of parallel lines at an angle of 45 ° to the center line or to the contour line, taken as the main one. The slope of the hatching lines can be either to the left or to the right. Two adjoining figures hatch in different directions. If a third one adjoins two adjoining figures, then the hatching can be diversified by increasing or decreasing the distance between the hatching lines. Non-metallic materials, including fibrous monolithic and slab (pressed) in sections hatch in a cage. TASK: Draw the given lines and images (in accordance with the task option, Figure 1, 2), observing their indicated location. The thickness of the lines should be carried out in accordance with GOST 2.303 - 68, do not apply dimensions. The task is to be carried out on a sheet of drawing paper in A4 format. INSTRUCTIONS FOR COMPLETING THE JOB It is more convenient to start the task by drawing a thin vertical line through the middle of the inner frame of the drawing, on which marks are made in accordance with the dimensions given in the task. Thin auxiliary horizontal lines are drawn through the marked points, which facilitate the drawing of the graphic part of the task. On the vertical axes intended for circles, points are applied through which the circles are drawn with the lines indicated in the task. In training drawings, a solid main thick line is usually made with a thickness of s \u003d 0.8 ... 1 mm. Figure 1 - even numbers of options Figure 2 - odd numbers of options PRACTICAL WORK No. 4 PERFORMING A DRAWING OF A PART WITH CONJUTIONS Purpose of work: to study the implementation of conjugations of curves, to draw a part with conjugations 1. Dividing circles into equal parts Dividing a circle 4 and 8 equal parts 1) Two mutual perpendiculars of the diameter of the circle divide it into 4 equal parts (points 1, 3, 5, 7). 2) Next, divide the right angle into 2 equal parts (points 2, 4, 6, 8) (Figure 1 a). Dividing a circle into 3, 6, 12 equal parts 1) To find points dividing a circle of radius R into 3 equal parts, it is enough from any point on the circle, for example point A (1), to draw an arc with radius R. (t.2,3) (Figure 1 b). 2) We describe the arcs R from points 1 and 4 (Figure 1 c). 3) We describe the arcs 4 times from points 1, 4, 7, 10 (Figure 1d). abc where Figure 1 - Division of circles into equal parts a - into 8 parts; b - into 3 parts; c - into 6 parts; g - into 12 parts; d - into 5 parts; e - into 7 parts. Dividing the circle into 5, 7, equal parts 1) From point A with radius R, draw an arc that intersects the circle at point n. From point n, a perpendicular is lowered to the horizontal center line, point C is obtained. From point C with radius R1 \u003d C1, an arc is drawn that intersects the horizontal center line at point m. From point 1 with radius R2=1m, an arc is drawn that intersects the circle at point 2. Arc 12=1/5 of the circumference. Points 3,4,5 are found by setting aside segments equal to m1 with a compass (Figure 1 e). 2) From point A we draw an auxiliary arc with radius R, which intersects the circle at point n. From it we lower the perpendicular to the horizontal center line. From point 1 with radius R=nc, 7 notches are made around the circumference and 7 desired points are obtained (Figure 1 e). 2. Construction of mates A mate is a smooth transition from one line to another. For accurate and correct execution of drawings, it is necessary to be able to build mates, which are based on two provisions: 1. To mate a straight line and an arc, it is necessary that the center of the circle to which the arc belongs lies on the perpendicular to the straight line, restored from the mate point (Figure 2 a ). 2. To conjugate two arcs, it is necessary that the centers of the circles to which the arcs belong lie on a straight line passing through the conjugation point (Figure 2 b). Figure 2 - Provisions on mates a - for a straight line and an arc; b - for two arcs. Conjugation of two sides of an angle with an arc of a circle and a given radius Conjugation of two sides of an angle (acute or obtuse) with an arc of a given radius is performed as follows: Parallel to the sides of the angle at a distance equal to the radius of the arc R, two auxiliary straight lines are drawn (Figure 3 a, b). The point of intersection of these lines (point O) will be the center of the arc of radius R, i.e. pairing center. From the center O, an arc is described, smoothly turning into straight lines - the sides of the angle. The arc ends at the junction points n and n1, which are the bases of the perpendiculars dropped from the center O to the sides of the corner. When constructing a conjugation of the sides of a right angle, it is easier to find the center of the conjugation arc using a compass (Figure 3c). From the top of the corner A, an arc is drawn with a radius R equal to the radius of the conjugation. Conjugation points n and n1 are obtained on the sides of the corner. From these points, as from centers, arcs of radius R are drawn to mutual intersection at point O, which is the center of conjugation. From the center O describe the conjugation arc. Figure 3 - Conjugation of corners a - acute; b - stupid; in - direct. Conjugation of a straight line with an arc of a circle Conjugation of a straight line with an arc of a circle can be performed using an arc with an internal touch (Figure 4 b) and an arc with an external touch (Figure 4 a). To build a conjugation by external contact, a circle of radius R and a straight line AB are drawn. Parallel to the given straight line at a distance equal to the radius r (radius of the mating arc), a straight line ab is drawn. From the center O, a circular arc is drawn with a radius equal to the sum of the radii R and r, until it intersects with the straight line ab at the point O1. Point O1 is the center of the conjugation arc. The conjugation point with is found at the intersection of the straight line OO1 with an arc of a circle of radius R. The conjugation point C1 is the base of the perpendicular dropped from the center O1 to this straight line AB. With the help of similar constructions, points O2, C2, C3 can be found. In Figure 6 b, an arc of radius R is paired with a straight AB arc of radius r with internal touch. The center of the conjugation arc O1 is located at the intersection of an auxiliary straight line drawn parallel to this straight line at a distance r with an arc of an auxiliary circle circumscribed from the center O with a radius equal to the difference R-r. The conjugation point is the base of the perpendicular dropped from the point O1 to the given line. The junction point with is found at the intersection of the straight line OO1 with the mating arc. ab Figure 4 - Conjugation of an arc with a straight line a - with an external touch; b - with internal touch. Conjugation of an arc with an arc The conjugation of two arcs of circles can be internal, external and mixed. With internal mating, the centers O and O1 of the mating arcs are inside the mating arc of radius R (Figure 5 a). With external mating, mating arcs of radius R1 and R2 are outside the mating arc of radius R (Figure 5 b). With mixed mating, the center O1 of one of the mating arcs lies inside the mating arc of radius R, and the center O of the other mating arc is outside it (Figure 5 c). abc Figure 5 - Conjugation of arcs a - internal; b - external; c - mixed. When drawing the contours of complex parts, it is important to be able to recognize certain types of mates in smooth transitions and be able to draw them. To acquire skills in building conjugations, exercises are performed on drawing the contours of complex parts. To do this, it is necessary to determine the order in which conjugations are constructed, and only after that proceed with their implementation. TASK: Draw images of the contours of the parts indicated in the task drawing, apply dimensions. The task is to be performed on a sheet of drawing paper in A4 format. Instructions for completing the task When performing each task, a certain sequence of geometric constructions must be observed: - axial, center lines, main descriptive; - arcs, roundings; - stroke, hatching, extension lines; - sizes. Task options PRACTICAL WORK No. 5 PERFORMING VIEWS ACCORDING TO THE AXONOMETRIC IMAGE OF THE DETAILS Purpose of the work: obtaining skills in building projections of the part model. TASK: to build three types of details according to this visual image in axonometric projection in accordance with the task option. The task is performed on sheets of drawing paper of A3 or A2 format (GOST 2.301-68). After drawing the frame on the sheet in the lower right corner, the dimensions of the main inscription of the task are outlined, which is the same for all formats. The form of the main inscription is adopted in accordance with the requirements of GOST 2.104-68. Images, if necessary, to scale, GOST 2.302-68. When filling in the main and other inscriptions, it is required to comply with the requirements of GOST 2.304-81. When applying dimensions, it is recommended to use GOST 2.307-68. When tracing the image, the thickness of the main lines should be 0.8 - 1.0 mm, and the thickness of the remaining lines - according to GOST 2.303-68 (ST SEV 1178-78). Objects on technical drawings are depicted by the method of rectangular projection onto six faces of a hollow cube. It is assumed that the depicted object is located between the observer and the corresponding face of the cube (see Fig. 1). The faces of the cube are taken as the main projection planes. There are six main projection planes: two frontal -1 and 6 (front view or main view, rear view), two horizontal -2 and 5 (top view and bottom view), two profile -3 and 4 (left view and right view) . The main projection planes are combined into one plane together with the images obtained on them. The image on the frontal projection plane is taken as the main one in the drawing. The object is positioned relative to the frontal plane of projections so that the image on it - the main image - gives the most complete idea of the shape and size of the object. Items should be depicted in a functional position or in a position convenient for their manufacture. Objects consisting of several parts should be depicted in a functional position. The question of which of the main views should be used in the product drawing should be decided so that, with the least number of views in combination with other images (local and additional views, sections and sections, detail elements), the drawing fully reflects the design of the product. The order of the task: 1) study GOST 2.305-68, 2.307-68; 2) carefully familiarize yourself with the design of the figure according to its visual image and determine the main geometric bodies of which it consists; 3) select on a sheet of paper the appropriate area for each type of detail; 4) apply thinly with a pencil all the lines of the visible and invisible contour, mentally dividing the part into basic geometric bodies; 5) apply all the necessary extension and dimension lines; 6) put down the dimensional numbers on the drawing; 7) fill in the main inscriptions and check the correctness of all constructions; 8) circle the drawing with a pencil. Task options PRACTICAL WORK No. 6 IMPLEMENTATION OF A TECHNICAL DRAWING OF A SIMPLE DETAILS A technical drawing is a visual image that has the basic properties of axonometric projections or a perspective drawing, made without the use of drawing tools, on an eye scale, in compliance with proportions and possible shading of the form. A technical drawing can be made using the central projection method, and thereby obtain a perspective image of the object, or the parallel projection method (axonometric projections), constructing a visual image without perspective distortions. A technical drawing can be performed without revealing volume by shading, with shading of volume, as well as with the transfer of color and material of the depicted object. In technical drawings, it is allowed to reveal the volume of objects by means of shading (parallel strokes), shading (strokes applied in the form of a grid) and dot shading. The most commonly used technique for detecting the volumes of objects is shading. It is generally accepted that rays of light fall on an object from the top left. Illuminated surfaces are not hatched, while shaded surfaces are covered with hatching (dots). When hatching shaded areas, strokes (dots) are applied with the smallest distance between them, which allows you to get a denser hatching (point shading) and thereby show shadows on objects. Table 1 shows examples of identifying the shape of geometric bodies and details using shading techniques. Rice. Fig. 1. Technical drawings with volume detection by shading (a), shading (b) and dot shading (e) Table1. Form shading by shading techniques Technical drawings are not metrically defined images if they are not sized. An example of constructing a technical drawing in a rectangular isometric projection (isometry) with a distortion coefficient of all axes equal to 1. When deposition of the true dimensions of the part along the axes, the drawing is 1.22 times larger than the real part. Methods for constructing an isometric projection of a part: 1. The method for constructing an isometric projection of a part from a shaping face is used for parts whose shape has a flat face, called a shaping face; the width (thickness) of the part is the same throughout, there are no grooves, holes and other elements on the side surfaces. The sequence of building an isometric projection is as follows: * building axes of an isometric projection; * construction of an isometric projection of the shaping face; * construction of projections of the remaining faces through the image of the edges of the model; stroke of the isometric view (Fig. 1). Rice. 1. Construction of an isometric projection of a part, starting from the shaping face 2. The method of constructing an isometric projection based on sequential removal of volumes is used in cases where the displayed form is obtained by removing any volumes from the original form (Fig. 2). 3. The method of constructing an isometric projection based on a sequential increment (adding) of volumes is used to perform an isometric image of a part, the shape of which is obtained from several volumes connected in a certain way to each other (Fig. 3). 4. Combined method of constructing an isometric projection. An isometric projection of a part, the shape of which was obtained as a result of a combination of various shaping methods, is performed using a combined construction method (Fig. 4). The axonometric projection of the part can be performed with the image (Fig. 5, a) and without the image (Fig. 5, b) of the invisible parts of the form. Rice. Fig. 2. Construction of an isometric projection of a part based on successive removal of volumes. Fig. 3. Construction of an isometric projection of a part based on a successive increment of volumes. Fig. 4. Using the combined method of constructing an isometric projection of a part. 5. Variants of the image of isometric projections of the part: a - with the image of invisible parts; b - without images of invisible parts TASK: in accordance with the variant of the task and the dimensions of the part, build a technical drawing on A4 checkered paper in a rectangular isometric projection. Task options Option 1-2-3 Option 4-5-6 Option 7-8-9 Option 10-11-12 Option 13-14-15 Option 16-17-18 Option 19-20-21 Option 22-23-24 -25 1
Topic: "Geometric characteristics of flat sections"
Objective:
Determination of the moments of inertia of complex shapes made up of simple geometric shapes and standard rolled profiles
The student must know:
- moments of inertia of simple sections;
- methodology for determining the main axes of inertia;
The student must be able to:
- determine the moments of inertia of a section with one or two axes of symmetry;
- determine the moments of inertia of a section made up of standard rolled profiles.
Questions for self-control:
- How are the coordinates of the center of gravity of a figure determined?
- What moments of inertia are called axial, polar and centrifugal?
- What are the units for moments of inertia?
- Write the transition formula for the axial moment of inertia with parallel translation of the axes.
- Write the formula for the axial moments of inertia for simple geometric shapes.
- How to determine the moment of inertia of a composite section?
- How to determine the moments of inertia of standard rolled profiles?
- What are the principal axes of inertia?
- What is the principal moment of inertia?
Guidelines
1. (see the procedure for solving the problem for settlement and graphic work No. 3).
2. Draw central axes for each rolled profile or simple geometric figure. These axes are called central axes. For the first figure, axes x 1 and y 1 are drawn, for the second - x 2 and y 2, etc.
3. They pass through the center of gravity of the entire section. One of the axes is combined with the axis of symmetry (in the task, all sections have such an axis), and the second is drawn through the center of gravity of the section perpendicular to the first. The vertical axis is denoted by , and the horizontal by u.
4. Find the moments of inertia of the section about the main central axes. In general, the moments of inertia of the section are determined by the formulas:
about the u-axis
about the axis
where J u and J are the moments of inertia of the section about the main central axes u and (main central moments of inertia); J , J , …, J - moments of inertia of simple figures (1, 2,..., n) relative to the main central axis u; J , J , ..., J - the same, relative to the axis.
The moments of inertia of simple figures about the axes u and are determined by the formulas:
about the u-axis
about the axis
where J x , J x , ..., J x - moments of inertia of simple figures (1, 2, ..., n) relative to their own central axes x 1 , x 2 ,..., x n . They are determined according to the GOST tables (see Appendix 1) for rolled steel profiles and formulas for simple geometric shapes; J y , J y , ..., Jy - the same, relative to the axes y 1 , y 2 , ..., y n ; a 1 , a 2 , ..., and n is the distance from the main central axis u to the central axes x 1 , x 2 , ..., x n ; b 1 , b 2 , …, b n . - the same, from the axis to the axes y 1 , y 2 , ..., y n ; A 1, A 2, ..., A n - cross-sectional areas of rolled steel profiles or simple geometric shapes.
If the main central axis coincides with the own central axis of some profile or figure, then its moment of inertia about the main central axis is equal to the moment of inertia about its own axis, since the distance between them is zero.
When determining the geometric characteristics, it must be taken into account that the rolled profiles on a given section can be oriented differently than in GOSTs. For example, the vertical y-axis according to GOST on a given section may turn out to be horizontal, and the horizontal x-axis - vertical. Therefore, it is necessary to carefully monitor with respect to which axes the geometric characteristics should be taken.
Example 1 Determine the main moments of inertia of the section shown in fig. 19. The section consists of two corners 56 4 and channel No. 18.
Decision
1. Determine the position of the center of gravity of the section(see settlement and graphic work No. 3). Center of gravity coordinates: x c \u003d O; y c \u003d 2.43 cm.
2. Draw central axes x 1, x 2, x 3 and axes y 1, y 2, y 3 through the centers of gravity of figures 1, 2, 3.
3. Draw the main central axes. The axis is compatible with the y-3 axis of symmetry. We draw the u axis through the center of gravity of the section C perpendicular to the axis. The axes and y 3 coincided.
4. Determine the main moment of inertia about the u axis:
From Fig. 19 it follows that the corners are the same and are located at the same distance from the axis u, i.e. A 1 \u003d A 2 and a 1 \u003d a 2.
Therefore, the formula for determining can be written:
Example 2 Determine the moment of inertia of the section shown in fig. 20, relative to the main central axis, which is not the axis of symmetry of the section. The section consists of an I-beam No. 24 and a channel No. 24a.
"Mutual intersection of surfaces"
Exercise:
On A4 format, draw a line of mutual intersection of two surfaces. Write down an algorithm for solving the problem.
Instructions for performing graphic work No. 6. According to your version on A4 format, build two projections of given surfaces, magnifying the image several times, so that the sheet occupancy is 80%. In the drawing, keep the projection connection lines between the projections.
To construct the points of the line of mutual intersection of two surfaces, you need to use the most rational way of solving. It should, if possible, choose such auxiliary cutting planes or surfaces that, in intersection with the given surfaces, give the simplest lines for drawing: circles or straight lines.
When constructing a line of mutual intersection of surfaces, first of all, it is necessary to determine its characteristic points - the points of intersection of the outline generators of one surface with another surface, the upper and lower, extreme right and left points (if any).
Draw auxiliary projecting (horizontally projecting or frontally projecting) planes, construct lines of intersection of these auxiliary planes with given surfaces. Determine the points of mutual intersection of the constructed lines. These points will belong to the desired line of mutual intersection of the given surfaces.
To find all the necessary points, you need to draw several auxiliary planes and repeat the construction. Next, determine visibility. Write down an algorithm for solving the problem, having previously designated the surfaces and auxiliary cutting planes with capital letters of the Greek alphabet. Use different colors to tone the resulting images.
An example of the work performed is shown in Figure 14.
Data for Graphic Work No. 6
"Crossing Surfaces"
Objective: study the types of gears; learn how to calculate the geometric and design parameters of the gear and carry out its working drawing; study the types of roughness, their symbols and methods of drawing on the drawing.
2). Make a drawing of a gear wheel in accordance with GOST 2.403-75. Select the design features of the gear wheel yourself, the connection of the wheel and shaft is keyed. The dimensions of the keyway should be set according to GOST 23360-76.
The task is performed on the A4 or A3 format, the main inscription according to the form 1 GOST 2.104-68. In the column “Designation” of the main inscription, sign MCH XX.05 in font No. 10, where MCH is the topic of the task (machine-building drawing), XX is the number of the task option, 05 is the number of the work in order. In the column “Name” of the main inscription, sign “Toothed wheel”.
See Appendix 6 for an example of the work being done.
Work order:
1). On a sheet of A3 format, draw a frame and a stamp of the main inscription.
2). According to the given values of the module, the number of teeth of the wheel, calculate all its parameters (see tables 7, 8).
3). In accordance with GOST, select the key and the dimensions of the keyway (Fig. 94 a and Table 10).
CONNECTIONS WITH KEYS [GOST 23360-78]
 |
 |
Fig.94 a. Parallel connections
Table 10. Dimensions of keys and keyways (in mm.)
| Shaft diameter d | Key | Groove | ||||
| b | h | l | t1 | t2 | c | |
| 6 - 8 | 6 -20 | 1,2 | 1,0 | 0,08 – 0,16 | ||
| 8 – 10 | 6 -36 | 1,8 | 1,4 | |||
| 10 -12 | 8 -45 | 2,5 | 1,8 | |||
| 12 - 17 | 10 -56 | 3,0 | 2,3 | 0,16 -0,25 | ||
| 17 – 22 | 14 -70 | 3,5 | 2,8 | |||
| 22- 30 | 18 -90 | 4,0 | 3,3 | |||
| 30 – 38 | 22 -110 | 5,0 | 0,25 -0,40 | |||
| 38 – 44 | 28 -140 | |||||
| 44- 50 | 36 -160 | 5,5 | 3,8 |
Note:
one). The standard provides connection dimensions for shafts up to 500 mm in diameter.
2). A range of standard lengths l keys, mm: 6; eight; ten; 12; fourteen; sixteen; eighteen; 20; 22; 25; 28; 32; 36; 40; 45; fifty; 56; 63; 70; 80; 90; 100; 110; 125; 140; 160;E; 500.
4). Independently choose the design features of the gear and draw it according to the calculated parameters (Fig. 94 b).
5). Enter the dimensions of the part.
6). Determine the surface roughness of the part.
7). Draw and fill in the table of gear parameters.
The table should contain 3 lines: number of teeth, module, normal initial contour.
eight). Fill in the stamp of the main inscription in accordance with the task (see Appendix 6).
Rice. 94 b Gear wheel and its parameters
THREADS. GRAPHIC WORK №7 "THREADED CONNECTIONS"
Theoretical Provisions
Detachable connections of machine parts, carried out with the help of threads, have become widespread in modern mechanical engineering. A threaded connection can ensure the relative immobility of parts or the movement of one part relative to another. The main connecting element in a threaded connection is a thread.
carving called the surface formed during the helical movement of a flat contour along a cylindrical or conical surface. In this case, a helical protrusion of the corresponding profile is formed, limited by helical and cylindrical or conical surfaces (Fig. 95, a).
Rice. 95. Carving
Thread classification:
According to the shape of the surface on which it is cut: cylindrical, conical;
According to the location of the thread on the surface of the rod or hole: external, internal;
Profile shape: triangular, rectangular, trapezoidal, round;
By appointment: fastening, fastening-sealing, running, special, etc.;
In the direction of the helical surface: left and right;
By number of visits: single-pass and multi-pass.
Thread parameters
All threads are divided into two groups: standard and non-standard; for standard threads, all their parameters are determined by standards.
GOST 11708-82 defines the following basic thread parameters:
1). Diameters threads: outer d (D), internal d1 (D1), average d2 (D2).
External thread diameters indicate d, d1, d2, and the internal thread in the hole - D, D1 and D2. Outer thread diameter d(D)- the diameter of an imaginary cylinder described around the tops of the external or troughs of the internal thread. This diameter is decisive for most threads and is included in the thread symbol (Fig. 96).
Fig.96 Basic thread parameters
2). Profile thread - the contour of the thread section by a plane passing through its axis (Fig. 95.96).
3). Profile angle carving α – the angle between the sides of the profile (Fig. 96).
4). Step carving R - the distance between adjacent profile sides of the same name in the direction parallel to the thread axis (Fig. 96).
5). Thread stroke t - the distance between the nearest side faces of the same name of the profile belonging to the same helical surface, in a direction parallel to the thread axis (Fig. 95). In a single-start thread (Fig. 84, a) the stroke is equal to the pitch, and in a multi-start thread (Fig. 95 b ) - step product R on the number of visits n (t = pР).
6). thread length l , thread length with full profile l 1 (Fig. 97 a).
7). Escape thread - a section of an incomplete profile in the zone of transition of the thread to the main part of the object (Fig. 97).
8). disclaimer carving l 4 - the value of the uncut part of the surface between the ends of the run and the supporting surface of the part.
9). undercut thread includes thread run-out and thread underrun. To eliminate thread run-out or undercut, perform grooveb (Fig. 97 b ).
ten). conical chamfer with serves to facilitate the screwing in of the threaded rod. It is performed at the end of the thread at an angle of 45 ° (Fig. 97 b ).
Fig.97 Thread parameters
Consider general purpose standard threads.
Thread metric is the main mounting thread. This is a single-start thread, mostly right-handed, with a large or small pitch. The metric thread profile is an equilateral triangle. The protrusions and cavities of the thread are blunt (Fig. 98) (GOST 9150-81).
Thread tubular cylindrical has a profile in the form of an isosceles triangle with an angle at the top of 55 ° (Fig. 99), tops and troughs are rounded. This thread is used in pipelines and pipe connections (GOST 6351-81).
Thread trapezoidal serves to convey movement and effort. The profile of the trapezoidal thread is an isosceles trapezoid with an angle between the sides of 30 ° (Fig. 100). For each diameter, the thread can be single-start and multi-start, right-hand and left-hand (GOST 9484-81).
Thread stubborn has a profile of an unequal trapezoid (Fig. 101). The profile cavities are rounded, there are three different pitches for each diameter. Serves for transmission of movement with large axial loads (GOST. 10177-82).
Thread round for plinths and cartridges, for safety glasses and lamps, for sanitary fittings (GOST 13536-68) has a profile obtained by pairing two arcs of the same radius (Fig. 102) (GOST 13536-68).
Thread conical inch with a profile angle of 60° (GOST 6111-52) is used for hermetic connections in pipelines of machines and machine tools; cut on a conical surface with a taper of 1:16 (Fig. 103).
Thread pipe conical has a profile similar to that of a cylindrical pipe thread; used in valves and gas cylinders. It is possible to connect pipes having a conical thread (taper 1:16) with products having a cylindrical pipe thread (GOST 6211-81).
Special threads are threads with a standard profile, but different from the standard dimensions of the diameter or thread pitch, and threads with a non-standard profile.
non-standard thread - square and rectangular(Fig. 104) are made according to individual drawings, on which all thread parameters are specified.
Rice. 104 Non-standard thread
Thread image in the drawing, it is performed in accordance with GOST 2.311-68 and depends only on what surface it is cut on: on the rod (outer) or in the hole (inner).
1).outdoor the thread is depicted with solid main lines along the outer diameter and solid thin lines along the inner diameter (Fig. 105).
Rice. 105 External thread illustration
2). internal the thread is depicted with solid main lines along the inner diameter and solid thin lines along the outer diameter (Fig. 106). Hatching in cuts and sections is brought to a solid main line.
Fig.106 Image of internal thread
In the left view, a solid thin line is drawn by an arc of 3/4 of the circumference, open anywhere, but not ending on the axes (Fig. 105, 106). A solid thin line when depicting a thread is drawn at a distance of at least 0.8 mm from the main line and not more than the thread pitch. The visible thread boundary is drawn by a solid main line at the end of the full thread profile to the line of the outer diameter of the thread. The thread run is depicted as a solid thin line (Fig. 107).
Rice. 107 External thread with taper
AT threaded connections the thread is conditionally drawn on the rod, and in the hole - only that part of the thread that is not closed by the rod (Fig. 108).
Rice. 108 Illustration of a part of a threaded connection
Thread designation includes: thread type, size, thread pitch and lead, tolerance field, accuracy class, thread direction, standard number.
one). The type of thread is conditionally indicated:
M - metric thread (GOST 9150-81);
G - cylindrical pipe thread (GOST 6357-81);
T g - trapezoidal thread (GOST 9484-81);
S - thrust thread (GOST 10177-82);
Rd - round thread (GOST 13536-68);
R - pipe conical outer (GOST 6211-81);
Rr - internal conical (GOST 6211-81);
Rp - internal cylindrical (GOST 6211-81);
K - conical inch thread (GOST 6111-52).
2). The size of conical threads and cylindrical pipe threads is conventionally indicated in inches (1 "= 25.4 mm), for all other threads, the outer diameter of the thread is affixed in millimeters.
3). The thread pitch is not indicated for metric coarse threads and for inch threads, in other cases it is indicated. For multi-start threads, the thread designation includes the thread lead, and the pitch is affixed in brackets.
4). The direction of the thread is indicated only for the left thread (LH), it is not indicated for the right thread.
5). The tolerance field and the accuracy class of the thread on the training drawings can be omitted.
Thread designation examples:
M 30- metric thread with an outer diameter of 30 mm and a large thread pitch;
M 30 x 1.5- metric thread with an outer diameter of 30 mm, fine pitch 1.5 mm;
G 1 1/2-A- cylindrical pipe thread with a size of 1 1/2 ", accuracy class A;
Tr 40x6- single-start trapezoidal thread with an outer diameter of 40 mm and a pitch of 6 mm;
Tr20 x 8 (P4)- two-start trapezoidal thread with an outer diameter of 20 mm, a stroke of 8 mm and a pitch of 4 mm;
S 80 x 10- single-thread thrust thread with an outer diameter of 80 mm and a pitch of 10 mm;
S 80 x 20 (P10)- two-start thrust thread with an outer diameter of 80 mm, a stroke of 20 mm and a pitch of 10 mm;
Thread designations according to GOST 2.311-68 refer to the outer diameter (Fig. 109).
Fig.109 Designation of threads
