1. Fill in the blanks
1. The clamping of workpieces refers to the ________________ and _____________________________________________________________________________________________________________.
2. full positioning refers to ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________.
3. fixture consists of ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
4. The reasons for positioning errors are reference non-coin errors ΔB, __________________________.
5. According to their degree of generalization, machine tool fixtures are divided into three categories: ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
6. According to the workpiece processing requirements, determine the degree of freedom that the following workpiece should be limited:
(1) Milling plane on spherical workpiece
(1) Milling plane on spherical workpiece Limit: ______________________
(2) Diagram of workpiece milling groove
(2) Diagram of workpiece milling groove latch Limit: ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Restrictions: ______________________
(4) Milling the plane in the upper right corner Restrictions: ________________________________
2. Multiple choice
1. The basic requirement of positioning elements is to have sufficient stiffness, strength and a certain ().
A. Wear resistance B. Stability
2. Group fixtures belong to ( ) type fixtures
A. General fixture B. Adjustable special fixture C. Assembly fixture
3. Combined fixtures belong to ( ) type fixtures
A. General fixture B. Special fixture C. Assembly fixture
4. ( ) is the basis of the entire fixture.
A. Clip specific B. clamping device
5. The use of fixtures can greatly stabilize the processing quality of the entire batch of workpieces on the basis of reducing the workpiece ( ).
A. Processing cost B. Processing accuracy
6. The basic requirements for clamping components are to have sufficient strength, load-bearing capacity and ( )
A. Operability B. Seismic resistance
7. Among the outer cylindrical positioning elements, ( ) is the most widely used category.
A. V frame B. Positioning sleeve
8 When the workpiece is positioned using a mandrel, the positioning reference is ( )
A. Outer cylindrical surface of the mandrel B. Inner cylindrical surface of the workpiece
C. Center line of the inner cylindrical surface of the workpiece D. Outer cylindrical surface of the workpiece
9 In the machine tool fixture, the component used to determine the position of the workpiece in the fixture is ( )
A. Positioning element B. Tool setting-guiding element C. Clamping element D. Connecting element
10 The basic function of the force transmission mechanism in the clamping device is ( )
A. Change the direction of the force B. Change the magnitude of the action C. Has certain self-locking performance D. The above are all
3. Judgment question
( ) 1. In various processes of mechanical manufacturing, in order to ensure processing accuracy, the workpiece is clamped and the process equipment is used to clamp the workpiece so that it occupies a certain position for processing or inspection, collectively known as fixtures.
( ) 2. The structure of a general-purpose fixture can be designed simply and compactly, with high positioning accuracy and quick and convenient operation.
( ) 3. The adjustable special fixture can adapt to changes in the local specifications and sizes of the workpiece through its own adjustment.
( ) 4. Assembling fixtures include two types: combined fixtures and standard assembling fixtures.
( ) 5. Generally speaking, you should try to avoid using positioning elements to participate in clamping and using positioning elements to withstand cutting forces.
( ) 6. Generally, fixtures are used for high efficiency and low cost.
( ) 7. The workpiece is clamped. It was positioned.
( ) 8. indexing head is a special fixture.
( ) 9. Special fixtures are suitable for single-piece mass production.
( ) 10. Combined fixtures are special fixtures, while grouped fixtures are assembled fixtures.
( ) 11. One side double pin positioning is a repeated positioning structure.
( ) 12. When positioning the workpiece, all six irregularities must be eliminated.
( ) 13. The workpiece is positioned with a small taper mandrel, which can eliminate 5 indefiniteness.
( ) 14. Repeated positioning is sometimes allowed and sometimes not allowed in production.
( ) 15. Underpositioning is not allowed to occur in actual production.
( ) 16. The height of the supporting nails can be adjusted when positioning the workpiece.
( ) 17. Using V-shaped block positioning, the structure is simple and good for neutrality, so there will be no positioning errors.
( ) 18. Considering the function of adjustable support and three basic components, the general ordinary cylinder screws and some tightening screws can be used for adjustable support.
( ) 19. The edge structure of the edge pin is designed to solve the repeated positioning and interference of the pin.
( ) 20. Disc sleeve parts are often positioned with the center line of the hole and combined with an end face.
( ) 21. The front and rear support parts of the automatic centering clamping mandrel can eliminate four indefinites of the workpiece, and the shaft shoulder eliminates one indefinite of the movement and rotation indefinites of the workpiece. .
( ) 22. When the workpiece is positioned with a cylindrical hole, the positioning reference is the hole surface.
( ) 23. When the workpiece is positioned on the dimension mandrel with a cylindrical hole, the hole and the mandrel have two contact methods: fixed single side and any side.
( ) 24. The reference displacement error of any side contact is twice the reference displacement error of fixed single-side contact.
( ) 25. As a standard mandrel, taper mandrel is widely used in high-precision positioning.
