Required dimensions on the assembly drawing. Engineering graphics. Theory
The following dimensions are indicated on the assembly drawings: overall, installation, installation, connection.
Dimensional Dimensions that determine the maximum external contours of the product are called. If the product has external moving parts that change its size, then it is allowed to depict them in extreme or intermediate positions with the appropriate dimensions.
The tread and section must be directly connected by superimposed geometric relationships. The sweep section does not have to be an ellipse. The handle will reach inside the mug. This is the result of the handle after emptying the mug of material. Solution: Perform a handle after emptying the mug of material. Completing the design using a hollow pen with inside. In some cases, depending on the desired wall thickness, this may not be the case. Requirement 5 How many cups of coffee fit into a cup.
Inputs: Inner diameter = 2.5 inches Outer diameter = 75 Thickness of bowl bottom = 25 Coffee level in cup is 5 less than cup height. A. Sold by the ounce of coffee, not by the inch. The mug capacity is 8 ounces. Require 6 Edit the drawing made in the lesson Edit the drawings that correspond to the round holes. Create new holes using the new drawing tools, use what you've learned about reference values and geometric relationships to measure, and layout the sketch correctly. Add the surface obtained by unraveling the back edge.
Mounting dimensions– dimensions required when assembling the product (distances between center lines).
Installation dimensions– dimensions indicating the installation location of one part relative to another when assembling the product.
Connection dimensions– dimensions of the element along which this product is connected to another. For example, outlet diameter, thread size, etc. Any of these dimensions can be reference and are marked in the drawing with an asterisk (*).
The result is shown in the figure below. Place the pointer at the end of the edge. Look for the sign indicating that you are at the end of the slime, this point is the center of the arc that must be reached. Hold down the mouse button and draw a radius to the end of the other edge and follow the shape of the pointer. Release the mouse buttons, it will set the arc radius. After tracing the circle, hide the lead line that will indicate the end point of the arc.
Select the bottom part of the drawing and insert a new sketch. Since you don't see the inverse shape in this view, select Select Other to select it. Use the Convert Objects command to copy the edges of the reverse drawing into the active sketch. Requirement 7 Use a revolutionary surface to create a toy after your own project. There are many ways to answer this question.
In the technical requirements, the following entry is made on the drawing: “* Dimensions for reference.” These include, for example, dimensions transferred from the drawings of parts included in the product, and used as installation and accessories.
connecting; dimensions defining the limiting positions of moving parts (piston stroke, valve rod stroke); overall dimensions, if they are transferred from the drawings of parts or are the sum of the dimensions of several parts.
Please note that the track profile should not intersect with the axis of symmetry. Enter the rotation angle. Examine the figure on the right before and after. What command do you think should be used to remove the missing portlets. You have the choice to choose the right one. The base of the part is always extruded. The sketch must be defined to help create a revolution. Study the picture on the right. Study the ellipse shown in the picture to the right. An axis of symmetry cannot be placed in another sketch. The profile must intersect the axis of symmetry.
2.1.3 Conventions and simplifications when executing an assembly drawing
Allowed:
Draw simplified illustrations of threaded and other fastening connections in accordance with GOST 2.315-68;
Do not show chamfers, roundings, grooves, recesses, protrusions, notches and other small elements, as well as gaps between the rod and the hole;
Place images of border (neighboring) products (“furnishings”) with solid thin lines;
The sketch is rotated around the axis of symmetry, thereby creating a three-point arc. . A three-point arc is a three-point arc, namely the starting point, the ending point and the midpoint of the arc. To create a three-point arc, follow these steps: Click and hold the left mouse button and drag the arc to its end point. Release the left mouse button. Drag the arc's midpoint to set the radius and direction. Spring pattern - tangential springs .
The Tangential Arc tool creates an arc that blends smoothly into an existing sketch. Manually add a tangent link. The arc start point must be connected to an existing sketch. Release the mouse button for pointer feedback. . As you sketch, the mouse pointer displays information about the objects in the sketch and the geometry of the model.
Typical, purchased and other widely used products (for example, oil cans) are depicted by external outlines;
Do not show components of the product that cover other parts of the product and make the drawing difficult to read (flywheels, casings, handles, partitions). In this case, an appropriate inscription is made above the image, for example “ Flywheel pos. 11 not shown» ;
Dashed lines show drawings showing alignment with other geometry alignment information is called inference lines has two different colors orange and blue line Inference orange captures and gives geometric relationships, such as the tangent of the blue line shows alignment and serves but does not capture or show geometric relationships.
You can use the Customize tools to add the Ellipse icon in the construction menu bar. Position the mouse cursor in the Ellipse Node. Click the mouse button - and the target object pointer in the horizontal direction to define the main axis. Release the mouse button. Place the mouse pointer on the ellipse curve. Release the mouse button.
Draw parts made of transparent material as opaque ;
Solid shafts, spindles, handles, and standard products are shown in longitudinal sections without being dissected. Components for which independent drawings have been issued, for example, a valve shutter, are also shown not dissected;
Parts located behind the coil spring, shown only as sections of the coils, are shown up to the center line of the sections of the coils ;
This results in an ellipse being drawn. Other information about the ellipse. Generating flattened objects - general provisions. A sweep route is a set of sketch curves illustrating a sketch, curve, or one or more muscles. The sweep section must be a closed loop, the starting point of the route must belong to the plane of the sketch section of the sweep section, the route and the resulting solid cannot intersect itself.
Create the route first and then the sweep section. Open a new plan drawing session 1 Draw the sweep path using the Line and Tangential Arc tools. The size of the sketch is as in the picture. Extruded cut using the Bevel Angle command .
Welded, soldered, riveted, etc. assembled products are hatched in sections in one direction, and the boundaries between parts are drawn with solid main lines ;
The moving parts of an assembly are usually shown in their working position. Extreme or intermediate positions are depicted along the contour by a dash-dot line with two dots.
This lesson contains: Review of Lesson 6-Revolution Surfaces and Unfolding Drawings Description of Lesson 7 Active Learning Exercises Five Minute Exercises Exercises and Projects Questions. Review of 6th generation surfaces and developments. Questions: List the steps required to create a revolutionary surface.
List the steps required to create a surface using a coaxial system. The functions and commands used in Lesson 7 are as follows: Overview of loft functions. Create a plane plane setting. Sketch profiles. Base loft. Exercises and Projects Requirement 1: Make a bottle as shown in the picture. All dimensions are indicated in millimeters. Requirement 2: Construct bottle 2 with an elliptical shape. The top of the glass is round. Draw a bottle of the desired size.
2.1.4 Specification
Specification – this is the main one design document per assembly unit. It determines the composition of the assembly unit and is necessary for the production and completion of design documents.
The specification includes all the components included in the specified product, as well as design documents related to this product and its components.
Requirement 3: Make a funnel in the following picture. The thickness of the funnel wall is 1 mm. A complete example is provided in the lesson file. Requirement 4: Complete the screwdriver in the picture below. Use inches as a unit of measurement. Follow the screwdriver handle for the first time to make it a revolutionary surface. Make the body of the screwdriver. The length of the screwdriver is 7 inches. The screwdriver tip is 2 inches. Calculate the length of the screwdriver body. Make the tip of the screwdriver a third shape.
Taking tangential relationships: When you want to move "smoothly" from one geometry to another using the loft command, some constraints need to be imposed. An example of this is shown in the figure below. The All Faces option will make all faces tangent tangent. Requirement 5: Create a 16-ounce sports bottle. Make a “cover” for sports glass. Connect the sports bottle with the cap.
A specification is a standard text document in tabular form, carried out in accordance with GOST 2.108 - 68* on A4 format (Appendix D). The first sheet of the specification contains the main inscription according to Form 2, all subsequent sheets - according to Form 2 a (Appendix B).
The specification consists of sections that are located in the following
sequences:
Documentation;
Assembly units;
Standard products;
Other products;
Materials.
The presence or absence of certain sections is determined by the composition
products. The name of each section is indicated as a heading. Overhead
the wok is separated from the bottom by an empty line and emphasized with a solid thin line -
to her. Sections are separated by free lines (at least one).
In the section "Documentation" in the column "Name" submit design documents compiled for the entire product as a whole. For example, an assembly drawing. In the column "Designation" the alphanumeric designation of the documents being recorded is indicated in the column "Format"– designation of the format in which this document is made.
To section "Assembly units" write down the name of the assembly
units pre-assembled and included in this product; V
graph "Designation"– designation of the assembly drawing of this unit, and in
graph "Format"– designation of the drawing format.
To section "Details" write down the name of all non-standard parts
lei of this product; in the column "Designation"– designation of the part drawing;
fill in the appropriate column "Format".
To section "Standard products" introduce the designations of standard
parts included in the assembly unit, indicating their corresponding
GOST. For example: Bolt M12x1.25x40.58 GOST 7798-70. The recording is made by groups of products, united by their functional purpose (for example, bearings, fasteners, etc.), within each group - in alphabetical order of product names, within each name - in ascending order of standard designations, and within each standard designations - in ascending order of the main parameters or dimensions of the product. Graphs "Designation" And "Format" do not fill out.
The specification is drawn up on separate sheets of A4 format (210x297 mm).
Assembly drawing
A graphic document containing an image of an assembly unit and other data necessary for its assembly (manufacturing) and control is called an assembly drawing.
The assembly drawing is carried out at the stage of development of working documentation based on the drawing general view products. Based on GOST 2.109-73 assembly drawing must contain:
An image of an assembly unit, giving an idea of the location and relationship of the components connected according to this drawing and providing the ability to assemble and control the assembly unit;
Dimensions and other parameters and requirements that must be fulfilled and controlled according to this drawing;
Instructions on the nature of mating of detachable parts of the product, as well as instructions on the method of connecting permanent connections, for example welded, soldered, etc.;
Number of positions of the components included in the product;
Main characteristics of the product;
Overall, installation, connection dimensions, as well as the necessary reference dimensions.
The number of images on the assembly drawing depends on the complexity of the product designs. A training assembly drawing is usually performed in two or three main images using sections. It is recommended to combine half the view with half the section if there is symmetry of the view and section of the product.
Sections and sections on assembly drawings serve to identify internal structure assembly unit and the relationship of its parts.
The section on the assembly drawing is a collection of sections of the individual parts included in the assembly unit. Hatching of the same part in sections in different images is performed in the same direction, maintaining the same distance (step) between the hatching lines. The shading of adjacent parts made of the same material can be varied by changing the direction of the shading, shifting the strokes or changing the shading pitch (Fig. 7.1). Welded, soldered or glued products from the same material, assembled with other products, are hatched in sections and sections as a monolithic body, showing the boundaries between the parts of the welded product with solid main lines (Fig. 7.2). Balls in sections and sections are always shown uncut. Screws, bolts, studs, pins, dowels, washers, nuts and other standard fasteners are shown uncut when viewed longitudinally. Non-hollow shafts, spindles, handles, connecting rods, etc., when viewed longitudinally, are also depicted as uncut (Fig. 7.3).
Figure 7.1
Figure 7.2
Figure 7.3
On assembly drawings it is allowed not to show chamfers, roundings, grooves, recesses, protrusions, corrugations, braiding and other small elements. It is allowed not to depict the gaps between the rod and the hole. If it is necessary to show the component parts of the product, closed with a lid, casing, shield, etc., then the closing products can not be depicted, and above the image an inscription like “Lid pos. 5 not shown."
Products made from a helical spring, depicted only as a section of the coils, are depicted only up to the zone that conventionally covers these products and is defined by the axial lines of the section of the coils (Fig. 7.4).
Figure 7.4
When making assembly drawings, the conventions and simplifications established by the standards for the rules for making drawings of various products are observed.
On the assembly drawing it is allowed to depict moving parts of the product in extreme or intermediate positions with corresponding sections, using thin dash-dotted lines with two dots (Fig. 7.5). To depict neighboring products - “furnishings” - thin solid lines are used (Fig. 7.6).
Figure 7.5 Figure 7.6
The following dimensions are indicated on the assembly drawings:
1. Overall dimensions characterizing three dimensions of the product. If one of the dimensions is variable due to the movement of moving parts of the product, then the dimensions at the extreme positions of the moving parts are indicated on the drawing (Fig. 7.7).
Figure 7.7
2. Installation dimensions indicating the relationship of parts in an assembly unit, for example the distance between the axes of the shafts, installation clearances, etc.
3. Installation dimensions that determine the dimensions of the elements on which the product is installed at the installation site or attached to another product, for example, the dimensions of circles and the diameters of holes for bolts, the distance between the axes of foundation bolts, etc.
4. Operational dimensions that determine the design, design characteristics products, for example, diameters of through holes, thread sizes on connecting elements, etc.
5. Assembly drawings also indicate the dimensions of holes for fasteners, if these holes are made during the assembly process.
6. All other parts of the assembly unit are numbered in accordance with the item numbers specified in the specification of this assembly unit.
7. Position numbers are indicated on the shelves of leader lines drawn from points on the images of the components of the assembly unit, which are projected as visible on the main views or sections replacing them. Position numbers are placed parallel to the main inscription of the drawing outside the outline of the image and grouped in a column or line, if possible on the same line (Fig. 7.7, 7.8, a). It is allowed to make a general leader line with vertical positions (Fig. 7.8, b). As a rule, the position number is applied to the drawing once. The font size of item numbers should be 1–2 sizes larger than the font size dimensional numbers on this drawing.
Figure 7.8
During the assembly process of a product, some technological, so-called fitting, operations are performed. They are performed by joint processing of connected parts or by fitting one part to another at the place of its installation. In these cases, text entries similar to those shown in Fig. are made on assembly drawings. 7.9.
Figure 7.9
Many products have standard components. These include, for example, stuffing box seals (Fig. 7.10). Their soft padding ensures the tightness of the holes through which the moving parts of the product pass. Hemp or flax fiber is used as padding (Fig. 7.10, a, b) or a set of rings made of asbestos, leather, rubber (Fig. 7.10, c). The packing is pressed using a union nut (Fig. 7.10, a), a threaded bushing (Fig. 7.10, b) or a stuffing box cover (Fig. 7.10, c). These parts are shown in the raised position on assembly drawings.
Figure 7.10
Valves have standard mountings on stems or spindles. Fastenings can be made either by crimping the valve (Fig. 7.11, a), or with a wire bracket (Fig. 7.11 b), or with a wire ring (Fig. 7.11, c). The spindle head can be mounted in the valve slot (Fig. 7.11, d).
Rolling bearings are standard products. They can be depicted in assembly drawings in a simplified manner (Fig. 7.12, a) without indicating the type according to GOST 2.420-69 or, as shown in Fig. 7.12, b, - with the image of rings and balls or rollers.
Figure 7.11
