Graphic work 16. Graphic work on drawing. Drawings used in the drawing
a) The construction of the third type in two given.
Construct the third type of the part according to two data, put down the dimensions, perform a visual image of the part in axonometric projection. Take the task from table 6. A sample of the task (Fig. 5.19).
Methodical instructions.
1. The drawing begins with the construction of the axis of symmetry of the species. The distance between the views, as well as the distance between the views and the frame of the drawing take: 30-40 mm. The main view and the top view are built. Two built views are used to draw the third view - the left view. This view is drawn according to the rules for constructing third projections of points for which two other projections are specified (see Figure 5.4 point A). When projecting parts of complex shape, you have to simultaneously build all three images. When constructing the third view in this task, as in the subsequent ones, you can not apply the projection axis, but use the “axisless” projection system. One of the faces can be taken as the coordinate plane (Fig. 5.5, plane P), from which the coordinates are counted. For example, having measured a segment on the horizontal projection for point A, which expresses the coordinate Y, we transfer it to the profile projection, we obtain the profile projection A 3. As the coordinate plane, you can also take the plane of symmetry R, \u200b\u200bthe traces of which coincide with the axial line of the horizontal and profile projection, and from it, take the coordinates Y С, Y А, as shown in Fig. 5.5, for points A and C.
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Fig. 5.4 Fig. 5.5
2. Every detail, no matter how complex it may be, can always be divided into a number of geometric bodies: a prism, a pyramid, a cylinder, a cone, a sphere, etc. Projecting a part comes down to projecting these geometric bodies.
3. The dimensions of objects should be applied only after constructing the left view, since in many cases it is advisable to apply a part of the dimensions on this view.
4. Axonometric projections are used in the technique for visualization of products or their components. It is recommended that you study the chapter "Axonometric projections" in the course of descriptive geometry.
For a rectangular axonometric projection, the sum of the squares of the distortion coefficients (indicators) is 2, i.e.
k 2 + m 2 + n 2 \u003d 2,
where k, m, n are the axial distortion coefficients (indicators). In isometric
projection, all three distortion factors are equal to each other, i.e.
k \u003d m \u003d n \u003d 0.82
For the sake of simplicity of constructing an isometric projection, the distortion coefficient (index) equal to 0.82 is replaced by the reduced distortion coefficient equal to 1, i.e. build an image of the subject, enlarged by 1 / 0.82 \u003d 1.22 times. The X, Y, Z axes in an isometric projection make angles of 120 ° between themselves, while the Z axis is directed perpendicular to the horizontal line (Fig. 5.6).
In the dimetric projection, two distortion coefficients are equal to each other, and the third in the particular case is taken to be 1/2 of them, i.e.,
k \u003d n \u003d 0.94; and m \u003d 1/2 k \u003d 0.47
In practice, for simplicity of constructing the dimetric projection, the distortion coefficients (indices) equal to 0.94 and 0.47 are replaced by the reduced distortion coefficient equal to 1 and 0.5, i.e. Build the image of the subject, enlarged 1 / 0.94 \u003d 1.06 times. The Z axis in rectangular dimetry is directed perpendicular to the horizontal line, the X axis is at an angle of 7 ° 10 ", the Y axis is at an angle of 41 ° 25". Since tg 7 ° 10 "≈ 1/8, and tg 41 ° 25" ≈ 7/8, these angles can be built without a protractor, as shown in Fig. 5.7. In rectangular dimetry, the natural dimensions are plotted along the X and Z axes, and along the Y axis with a reduction factor of 0.5.
The axonometric projection of a circle in the general case is an ellipse. If the circle lies in a plane parallel to one of the projection planes, then the small axis of the ellipse is always parallel to the axonometric rectangular projection of that axis that is perpendicular to the plane of the depicted circle, while the large axis of the ellipse is always perpendicular to the small.
In this task, it is recommended to perform a visual image of the part in isometric view.
b) Simple cuts.
Construct the third view of the part according to two data, perform simple cuts (horizontal and vertical planes), put down the dimensions, perform a visual image of the part in axonometric projection with a cutout of 1/4 part. Take the task from table 7. A sample of the task (Fig. 5.20).
Perform graphic work on a sheet of drawing paper in A3 format.
Methodical instructions.
1. When completing the task, pay attention to the fact that if the part is symmetrical, then it is necessary to combine half of the view and half of the section in one image. Moreover, in the form don't show invisible outline lines. The boundary between the appearance and section is the dash-dot axis of symmetry. Section image details is located from the vertical axis of symmetry to the right (Fig. 5.8), and from the horizontal axis of symmetry - from below (Fig. 5.9, 5.10) regardless of what plane of projections it is depicted on.
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Fig. 5.9 Fig. 5.10
If the projection of an edge belonging to the external outline of the object falls on the axis of symmetry, then the section is performed as shown in Fig. 5.11, and if an edge belonging to the internal outline of the object falls on the axis of symmetry, then the cut is performed as shown in Fig. 5.12, i.e. in both cases, the projection of the rib is preserved. The boundary between the section and the view is shown by a solid wavy line.
Fig. 5.11 Fig. 5.12
2. In the images of symmetrical parts, in order to show the internal structure in axonometric projection, a 1/4 part is cut out (the most illuminated and closest to the observer Fig. 5.8). This neckline is not associated with a section on orthogonal projections. So, for example, on a horizontal projection (Fig. 5.8), the axis of symmetry (vertical and horizontal) divide the image into four quarters. When performing an incision in the frontal projection, the lower right quarter of the horizontal projection is removed, and the lower left quarter of the model is removed on the axonometric image. Stiffeners (Fig. 5.8) that fall into a longitudinal section on orthogonal projections do not shade, but shade in axonometry.
3. The construction of the model in a perspective view with a cutout of one quarter is shown in Fig. 5.13. The model constructed in thin lines is mentally cut by the frontal and profile planes passing through the Ox and Oy axes. The quarter of the model enclosed between them is removed, the internal structure of the model becomes visible. Cutting the model, the planes leave a mark on its surface. One such trace lies in the frontal, the other in the profile plane of the section. Each of these tracks is a closed polygonal line consisting of segments along which the section plane intersects with the faces of the model and the surface of the cylindrical hole. Shapes lying in the section plane are hatched in axonometric projections. In fig. 5.6 shows the direction of the hatching lines in isometric projection, and in fig. 5.7 - in a dimetric projection. The hatching lines are drawn parallel to the segments that cut off the same segments on the axonometric axes Ox, Oy and Oz from the point O in the isometric projection, and the same segments in the dimetric projection on the Ox and Oz axes and the segment equal to 0.5 segments on the axis Oy Oh or Oz.
4. In this task, a visual image of the part is recommended to be performed in a dimetric projection.
5. When determining the true type of section, one must use one of the methods of descriptive geometry: rotation, alignment, plane-parallel displacement (rotation without indicating the position of the axes), or changing projection planes.
In fig. 5.14, the construction of the projections and the true sectional view is given by the frontally projecting plane Г of the quadrangular prism by the method of changing the projection planes. The frontal projection of the section will be the line coinciding with the trace of the plane. To find the horizontal projection of the section, we find the intersection points of the edges of the prism with the plane (points A, B, C, D), connecting them, we get a flat figure whose horizontal projection will be A 1, B 1, C 1, D 1.
symmetry parallel to axis x 12, will also be parallel to the new axis and be at a distance equal to b 1.In the new system of projection planes, the distances of the points to the axis of symmetry are kept the same as in the previous system, therefore, to find them, you can put off the distances ( b 2) from the axis of symmetry. Connecting the obtained points A 4 B 4 C 4 D 4, we obtain the true form of the section by the plane G of the given body.
In fig. 5.16, the construction of a true sectional view of a truncated cone is given. The major axis of the ellipse is defined by points 1 and 2, the minor axis of the ellipse is perpendicular to the major axis and passes through its middle, i.e. point O. The minor axis lies in the horizontal plane of the base of the cone and is equal to the chord of the circumference of the base of the cone passing through point O.
The ellipse is limited by the straight line of intersection of the secant plane with the base of the cone, i.e. a straight line passing through points 5 and 6. Intermediate points 3 and 4 are constructed using the horizontal plane G. In Fig. 5.17 given the construction of the section of the part, consisting of geometric bodies: cone, cylinder, prism.
 Fig. 5.16 |
 Fig. 5.17 |
c) Complex sections (complex stepwise section).
Construct the third view of the part according to two data, perform the specified complex cuts, construct an oblique section with the plane specified in the drawing, put down the dimensions, perform a visual image of the part in axonometric projection (rectangular isometry or dimetry). The task to take from table 8. A sample of the task (Fig. 5.21). Perform graphic work on two sheets of drawing paper in A3 format.
Methodical instructions.
1. When performing graphic work, it is necessary to pay attention to the fact that a complex step section is depicted according to the following rule: as if cutting planes are combined into one plane. The boundaries between the secant planes do not indicate, and this section is made out as a simple section, made not on the axis of symmetry.
2. In the task, part of the dimensions due to the lack of a third image is not reasonably placed, therefore, the dimensions must be applied in accordance with the instructions in the "Dimensioning" section, and not copied from the task.
3. In fig. 5.21. An example of the execution of a part image in rectangular isometry with a complex cutout is shown.
d) Complex sections (complex broken section).
Construct the third type of part according to two data, perform the specified complex polyline cut, put down the dimensions. Take the task from table 9. A sample of the task (Fig. 5.22).
Perform graphic work on a sheet of drawing paper in A4 format.
Methodical instructions.
In fig. Figure 5.18 shows an image of a complex broken section obtained by two intersecting profile-projecting planes. In order to obtain a cut in undistorted form when the object is cut by inclined planes, these planes together with the sectional figures belonging to them are rotated around the line of intersection of the planes to a position parallel to the projection plane (in Fig. 5.18 - to a position parallel to the frontal plane of the projections). The construction of a complex broken section is based on the method of rotation around the projecting line (see the course of descriptive geometry). The presence of kinks in the section line does not affect the graphic design of a complex section - it is designed as a simple section.
Options for individual tasks. Table 6 (Construction of the third type).
Examples of the assignment.
Fig. 5.22
Graphic work№1
Drawing fonts
Purpose: to check the assimilation of knowledge on the topic "Drawing fonts"
Efremov Secondary School
Education Technology
Subject Drawing
Graphic work
Performed
Name of student
Checked
Name of teacher
2013-2014 academic year
Graphic work№2
Division of a circle into equal parts
Purpose: to check the assimilation of knowledge on the topic "Division of a circle into equal parts"
I-option - in 3 parts
ІІ-option - into 5 parts
ІІІ-version - in 6 parts
ІҮ-variant - into 8 parts
Graphic work№ 5
purpose
I-option
Roller Steel 45
Graphic work№ 5
Sectional drawing of parts
ІІ option
purpose : check knowledge on the topic “Sections”
Finger Steel 50
Graphic work№ 5
Sectional drawing of parts
III version
Purpose: check the assimilation of knowledge on the topic "Sections"
Perform a sketch of a detail on a sheet of A4 paper in a visual image. Identify the transverse shape of the part by section. Label it if necessary. Dimension.
Roller Steel 45
Graphic work№ 5
Sectional drawing of parts
ІҮ-option
purpose : check knowledge on the topic “Sections”
Perform a sketch of a detail on a sheet of A4 paper in a visual image. Identify the transverse shape of the part by section. Label it if necessary. Dimension.
Axis Steel Art. 5
Graphic work№ 6
Sectional drawing of parts
Purpose: to check the assimilation of knowledge on the topic "Sections"
1st option
Perform a sketch of a detail on a sheet of A4 paper in a visual image. Cut Product
II variant
Graphic work№ 7
Threaded drawing
Purpose: to check the assimilation of knowledge on the topic "Connections"
Content: Draw a drawing of the connection of two parts using threaded products. Option 1
Graphic work№ 8
Content: Run. (The composition of the assembly unit:1 - sponge;2 - spring;3 - screw.) Option 1
Drawing of the part from life or according to the assembly drawing
Purpose: to check the assimilation of knowledge on the topic "Assembly drawing"
Runsketch of a part in an assembly drawing. (The composition of the assembly unit:1 - rod;2 - housing;3 - cover.)
Option 2
Graphic work№ 8
Drawing of the part from life or according to the assembly drawing
Purpose: to check the assimilation of knowledge on the topic "Assembly drawing"
Runsketch of a part in an assembly drawing. (The composition of the assembly unit:1 - flange;2 - a tube.)
Option 3
Graphic work№ 9
Sketch drawing details
Purpose: to check the assimilation of knowledge on the topic "Assignment and execution of sketches"
Contents: Complete the drawing of one part. Option 1
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Graphic work№ 10
Drawing of the plan and facade of the building
Purpose: to check the assimilation of knowledge on the topic "Elements of construction and topographic drawing"
Methods for constructing sections using the Compass 3D program. The sequence of graphic work No. 14 in the Compass program. Cutout and dimensioning. Rules for choosing the number of images and the main view. Conventions and simplifications when performing drawings. Practical work №15. "Reading the drawing details." Performing technical drawing according to the drawing. Graphic work No. 16. Performing a sketch from nature.
Classes are convenient for drawing lessons. If there is a computer class, then the first part of the course should be carried out in a computer class. If there is no computer class, then the first part of the course can be held in the form of homework. Classes can also be conducted at elective courses and elective courses. This type of training is also suitable for technology lessons when performing creative projects and training, for example, the preparation of technical documentation, technological maps, etc. .
Student requirements
The course is designed for students in grades 8 of a comprehensive school who study drawing and technology, as well as those who study in technical creativity circles or study elective courses in this area.
The student should have basic ideas about projection. Know the main types and sections, sections; rules for their implementation; conventions and simplifications when performing drawings having cuts and sections. To be able to read drawings having sections and cuts.
At the second stage, a single graphic work is performed, consisting of several sections, some of which are performed at home, and some in the audience.
HOME WORKS. The PIPELINE SCHEME is executed on a sheet of drawing paper of the A3 format located horizontally. The student performs a schematic diagram of the pipeline section with the elements included in it according to the individual task option. Separately, on a sheet of A4 format, a table of the list of elements included in the scheme is executed. An element should be included in the scheme, which is an assembly unit with which work is carried out in the audience.
The deadline is 8 weeks, estimated at 2 points.
DRAWING OF THE FLANGE JOINT is carried out on a sheet of drawing paper of the A3 format located horizontally. Separately, a specification is executed on an A4 sheet.
The deadline is 10 weeks, estimated at 2 points.
AUDITING WORK. SKETCHES AND TECHNICAL DRAWINGS OF THE ASSEMBLY UNIT PARTS. The work is performed on checkered sheets of A3 or A4 size paper. Each student will have their own assembly unit (crane, valve, gate valve, valve, etc.). The student, on the instructions of the teacher, performs sketches of 3 parts (drawings on an arbitrary scale, made by hand) with drawing all sizes, their maximum deviations and surface roughness parameters. Evaluated by 4 points.
In addition to sketches, the student, on the instructions of the teacher, performs technical drawings (axonometry by hand) of 2 parts with drawing dimensions. Estimated by 1 point.
CONTROL WORK - 8 points.
TASKS - 4 points.
In just 5-10 weeks, 21 points.
Graphic work 11-16 weeks
HOMEWORK. DETAILS OF THE DRAWING OF THE ASSEMBLY UNIT. The work is performed on a sheet of drawing paper in A2 format, which is divided into two A3 formats. On each format, a drawing of the part indicated by the teacher on the drawing of the assembly unit is carried out. On these formats, the necessary types, sections, sections are performed, the necessary sizes are applied. Each of the drawings is rated 1.5 points (total 3 points).
In addition, technical drawings of 2 parts are performed on checkered paper sheets. Each of them is estimated at 0.5 points (total 1 point).
AUDITING WORK. ASSEMBLY DRAWING. The work is performed on a sheet of drawing paper of A1 format, located vertically and is a continuation of the graphic work of the second stage. Separately, an assembly unit specification is performed on an A4 sheet. Work is rated 5 points.
TEST. Examination is devoted to detailing the drawing of an assembly unit (1 orthogonal drawing and 1 technical drawing are performed), it is estimated 8 points.
TASKS - 4 points.
In total, a student can get 21 points at 12-16 weeks, and 60 points for the whole semester.
NOTE. Each work is necessarily accompanied by filling in all the columns of the main inscription and re-designation. In the main inscription must be the signature of the student.
Entries in the column "designation"
The drawing in a visual image is IG-ПЧ-1-ЧНИ-ХХ, where ХХ is the option number.
Drawing by description - IG-PCh-2-ChPO-XX.
The scheme of the pipeline is IG-ТЧ-1-ХХ Т2, where ХХ is the option number.
Flange connection - IG-ТЧ-1-ХХ-СБ СБ
Part sketch, technical drawing IG-ТЧ-1-ХХ-ХХХ-Х, where ХХХ is the code of the assembly unit, ХХ is the option number, and X is the part number.
Assembly drawing - IG-ТЧ-1-ХХ-ХХХ СБ.
Detailing - IG-ТЧ-2-ХХХ-Х.