30. What are the methods to ensure the assembly accuracy?How are the methods applied?
1.Interchange method; 2. Selection method; 3. Repair method; 4. The adjustment method
31. What are the components and functions of jigs and fixtures?
A jig is a device for attaching and clamping workpieces to a machine tool.
The components are:
1. Locating element or device.
2. Tool guide element or device.
3. Clamp components or devices.
4. Coupling element
5. The concrete
6. Other components or devices.
Main functions:
1. Guarantee the processing quality
2. Improve production efficiency
3. Expand the range of machine tools
4. Reduce workers' labor intensity to ensure production safety.
32. According to the scope of fixture, how to classify the fixture?
1.General fixture; 2. Special fixture; 3. Adjustable fixture and group fixture; 4. Combination fixture and random fixture
33. The workpiece is positioned on a plane. What are the common positioning components?And analyze the elimination of degrees of freedom.
The workpiece is located on a plane. Common positioning elements are 1. Fixed support; 2. Adjustable support; 3. Self-positioning support; 4. Auxiliary support
34. The workpiece is positioned with cylindrical holes. What are the common positioning components?And analyze the elimination of degrees of freedom.
The workpiece is located with cylindrical holes.
Common locating elements include 1. mandrel; 2 locating pin
35, the workpiece outside the circular surface positioning, common positioning components are what?And analyze the elimination of degrees of freedom.
Surface positioning on the outer circular surface of the workpiece. Common positioning elements include v-shaped blocks
36, the workpiece to "one side and two pins" positioning, how to design two pins?
1. Determine the size and tolerance of the distance between the two pins
2. Determine cylindrical pin diameter and its tolerance
3. Determine the diamond pin width diameter and its tolerance.
37. What are the two aspects of the positioning error?What are the methods to calculate the positioning error?
Two aspects of positioning error.
1. The positioning error caused by inaccurate fabrication of the positioning element on the workpiece positioning surface or fixture is called the reference position error
2. The positioning error caused by the non-coincidence between the process datum and the positioning datum of the workpiece is called the non-coincidence error of the datum
38. Basic requirements for workpiece clamping device design.
1. During the clamping process, the correct position obtained when the workpiece is positioned should be maintained.
2. The clamping force is appropriate. The clamping mechanism should be able to ensure that the workpiece does not become loose or vibrate in the process of processing
3. The clamping device shall be easy to operate, labor-saving and safe.
4. The complexity and automation of the clamping device should be adapted to the production batch and mode.Structural design should be simple, compact and use standardized components
39.The three elements of clamping force?What are the principles of clamping force direction and action point selection?
Size, direction, point of action.
The choice of clamping force direction should generally follow the following principles:
1. The action direction of clamping force should be conducive to the accurate positioning of the workpiece without damaging the positioning. Therefore, it is generally required that the main clamping force points vertically to the positioning surface
2. The direction of clamping force should be consistent with the direction with large stiffness of the workpiece, so as to reduce the clamping deformation of the workpiece
3, the clamping force direction should be as far as possible with the cutting force, the direction of the workpiece gravity, in order to reduce the required clamping force.
General principles for the selection of clamping force action points:
1, the clamping force point should be directly against the supporting surface formed by the supporting element, in order to ensure that the positioning of the workpiece has been unchanged
2, the clamping force should be in a rigid position to reduce the workpiece clamping deformation
3, the clamping force should be as close as possible to the processing surface to reduce the cutting force caused by the workpiece turnover torque
40. What are the commonly used clamping mechanisms?The key analysis grasps the oblique wedge clamping mechanism.
1. Oblique wedge clamping structure
2. Screw clamping structure
3. Eccentric clamping structure
4. Hinge clamping structure
5. Centering clamping structure
6. Linkage clamping structure
41. How to classify according to the structural characteristics of drilling dies?How to classify according to the structural characteristics of drill sleeve?According to the drill template and clip specific connection mode into which several categories?
According to the characteristics of common structure:
1, fixed drill 2, rotary drill 3, flip drill 4, cover plate drill 5, sliding column drill
Structural characteristics of drilling dies:
1. Fixed drill die 2, changeable drill die 3, quick change drill die 4, special drill die
Drill template to clamp specific connection:
Stationary hinge type separated suspension type