Turning clamp capable of improving eccentric distance precision and machining method

Abstract

The invention relates to the field of machining, in particular to a turning clamp capable of improving eccentric distance precision and a machining method, and solves the problems of clamping, alignment and positioning when an eccentric outer circle is machined on a common lathe. The technical problems of clamping, alignment and positioning existing when an eccentric outer circle is machined on a common lathe at present are solved. The clamp comprises an eccentric body and a compression nut; the eccentric body comprises a first cylinder, a second cylinder, a third cylinder, a fourth cylinder and a fifth cylinder which are sequentially connected, the outer diameter of the second cylinder is the largest, the third cylinder and the second cylinder are coaxial, the first cylinder, the fourth cylinder and the fifth cylinder are coaxial and have the same eccentric distance with the second cylinder, and the eccentric distance is the same as that of a workpiece to be machined; the outer diameter of the second cylinder is provided with external threads; the fifth cylinder is matched with the inner diameter of the eccentric outer circle of the workpiece, and the third cylinder is matched with the inner diameter of the workpiece; and the inner wall of the compression nut is provided with an internal thread matched with the second cylinder.

Description

Technical Field

[0001] The invention relates to the field of mechanical processing, in particular to a lathe clamp and a processing method capable of improving the eccentricity precision, solving the difficult problems of clamping, aligning and positioning in processing eccentric outer circles on ordinary lathes. Background Art

[0002] The inner shell of a certain product is welded from two parts made of 1Cr18Ni9Ti and 0Cr18Ni10Ti (the specific structure is shown in the attached Figure 1 As shown in the figure), the original processing plan requires that when processing the eccentric outer circle and groove, an eccentric jacket (specific structure is shown in the attached figure) should be used first. Figure 2 , 3 As shown in the figure, clamp the processed φd3 outer circle on the workpiece, then use the four-jaw chuck to clamp the eccentric sleeve, and use the dial to align it with φD1 +0.036 0 φd3 outer circle generatrix with the same eccentric direction, and another side generatrix of the φd3 outer circle at 90° to this generatrix (the specific alignment position is as shown in the attached Figure 4 As shown) and the inner hole φD1 of the workpiece +0.036 0, and then process the eccentric outer circle φd1. However, in actual processing, each workpiece needs to be clamped with four claws and repeatedly checked and aligned, and the time for checking and aligning is long, and the processing efficiency is particularly low. It is not suitable for mass production. Summary of the invention

[0003] The invention provides a lathe clamp and a processing method which can improve the eccentricity accuracy in order to solve the technical problems of clamping, aligning and positioning existing in processing an eccentric outer circle on a common lathe.

[0004] The vehicle clamp capable of improving the eccentricity accuracy of the present invention is realized by adopting the following technical scheme: a vehicle clamp capable of improving the eccentricity accuracy comprises an eccentric body and a clamping nut; the eccentric body comprises a first, a second, a third, a fourth and a fifth cylinder connected in sequence, wherein the second cylinder has the largest outer diameter, the third cylinder is coaxial with the second cylinder, the first cylinder, the fourth cylinder and the fifth cylinder are coaxial and have the same eccentricity with the second cylinder, and the eccentricity is the same as the eccentricity of the workpiece to be processed; the outer diameters of the third cylinder, the fourth cylinder and the fifth cylinder decrease in sequence, and the outer circumference of the second cylinder is provided with an external thread; the end face where the second cylinder is connected to the third cylinder serves as a C face close to the workpiece to be processed; the fifth cylinder matches the inner diameter of the eccentric outer circle of the workpiece to be processed, the end face of the fifth cylinder is provided with a center hole, and the third cylinder matches the inner diameter of the workpiece to be processed; An inwardly contracted convex edge is arranged at one end of the clamping nut, and an internal thread matching the second cylinder is formed on the inner wall of the clamping nut.

[0005] Furthermore, the third cylinder adopts a chamfered pin structure.

[0006] Furthermore, the outer diameter of the third cylinder is φd7, and the portion of the third cylinder that hits the inner wall of the workpiece to be processed in the eccentric direction is eliminated, leaving a portion of the cylindrical surface perpendicular to the eccentric distance direction, forming a chamfered pin structure.

[0007] Furthermore, the cross-section of the third cylinder is a diamond-shaped structure, and the center line of the two sides perpendicular to the eccentricity direction serves as the major axis of the chamfered pin, with a size equal to φd7, and the center line of the two sides parallel to the eccentricity direction serves as the minor axis of the chamfered pin, with a size less than φd7; the outer diameter of the fifth cylinder is φd6.

[0008] A processing method capable of improving eccentricity accuracy according to the present invention comprises the following steps: 1) When machining an eccentric outer circle, first use a four-jaw chuck to clamp the lathe fixture, and use a dial to align the C surface on the lathe fixture and the outer circle of φd6, so that the dial runout is less than 0.01mm; 2) The workpiece to be processed is mounted on the eccentric body 1 of the vehicle fixture, and is positioned using the C surface, the φd6 outer circle and the positioning outer circle of the φd7 diamond structure of the vehicle fixture; 3) Connect the clamping nut 2 with the external thread on the eccentric body through the step surface on the outer circle of the workpiece φd3 to be processed, and lock the nut so that the left end face of the workpiece to be processed is close to the C surface of the eccentric body, so that the workpiece can be clamped; 4) Check the inner hole φD1 of the workpiece with a meter, and the meter jump is less than 0.01mm; 5) Use the center point to directly support the center hole of the eccentric body on the lathe fixture. As the lathe spindle rotates, the rotation center of the lathe spindle coincides with the center of the outer circle to be machined of the workpiece, and the workpiece can be machined.

[0009] Practice has proved that the workpiece processed according to this invention has the following processing advantages compared with the workpiece processed according to the prior art: 1) Reliably and stably guarantee the machining accuracy of the workpiece, fully meet the technical requirements of the product process, and better guarantee the machining quality of the product; 2) After aligning the lathe fixture once, multiple workpieces can be processed without the need to align the workpieces repeatedly; 3) It can quickly position and clamp the workpiece on the machine tool, shorten the auxiliary time, and increase the processing efficiency of the product by more than 5 times.

[0010] Therefore, using this lathe fixture to process eccentric outer circles on ordinary lathes is an easy-to-operate, economical, efficient and reliable processing method, which is suitable for mass production of workpieces. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the inner shell structure of the processed workpiece.

[0012] Figure 2 A schematic diagram of the cross-sectional structure of an existing eccentric jacket.

[0013] Figure 3 Schematic diagram of the main structure of the existing eccentric jacket.

[0014] Figure 4 Schematic diagram for aligning workpieces when clamping them with an eccentric clamp set.

[0015] Figure 5 A schematic structural diagram of the vehicle clamp of the present invention.

[0016] Figure 6 for Figure 5 DD cross-sectional diagram.

[0017] 1. Eccentric body, 2. Pressing nut, 3. Inner shell of the workpiece, 4. Eccentric sleeve. DETAILED DESCRIPTION

[0018] Embodiment 1 A vehicle clamp capable of improving the eccentricity accuracy comprises an eccentric body 1 and a clamping nut 2; the eccentric body 1 comprises a first, a second, a third, a fourth and a fifth cylinder connected in sequence, wherein the second cylinder has the largest outer diameter, the third cylinder is coaxial with the second cylinder, the first cylinder, the fourth cylinder and the fifth cylinder are coaxial and have the same eccentricity as the second cylinder, and the eccentricity is the same as the eccentricity of the workpiece to be processed; the outer diameters of the third cylinder, the fourth cylinder and the fifth cylinder decrease in sequence, and the outer circumference of the second cylinder is provided with an external thread; the end face where the second cylinder is connected to the third cylinder serves as a C face close to the workpiece to be processed; the fifth cylinder matches the inner diameter of the eccentric outer circle of the workpiece to be processed, the end face of the fifth cylinder is provided with a center hole, and the third cylinder matches the inner diameter of the workpiece to be processed; An inwardly contracted convex edge is provided at one end of the clamping nut 2, and the convex edge can be stuck on the step on the workpiece shell. At this time, the large-diameter end face of the workpiece to be processed is close to the C surface, and the inner wall of the clamping nut 2 is provided with an internal thread matching the second cylinder.

[0019] Embodiment 2 The third cylinder adopts a chamfered pin structure, and the outer diameter of the third cylinder is φd7. The part of the third cylinder that touches the inner wall of the workpiece hole to be processed in the eccentric direction is eliminated, leaving a part of the cylindrical surface perpendicular to the eccentricity direction to form a chamfered pin structure; the cross-section of the third cylinder is a diamond structure, and the center line of the two sides perpendicular to the eccentricity direction is used as the major axis of the chamfered pin, and the size is equal to φd7, and the center line of the two sides parallel to the eccentricity direction is used as the minor axis of the chamfered pin, and the size is less than φd7.

[0020] Now, we will take the processing of the inner shell of a product as an example to explain the processing plan of the eccentric outer circle. The product outline is shown in the attached Figure 1The workpiece includes a shell and an eccentric outer circle at one end of the shell, and a raised step surface is provided on the shell; the designed vehicle fixture is shown in the attached Figure 5 The processing scheme of the present invention is based on this aspect: design a special tool to ensure that when processing the eccentric outer circle of a certain product on an ordinary lathe, there is a clamping and positioning reference, and the workpiece can be quickly positioned and clamped on the machine tool, reducing the time for table alignment, improving processing efficiency, reducing processing costs, and ensuring processing quality. Therefore, the attached Figure 5 The car fixture shown meets all requirements during workpiece processing.

[0021] The scheme of processing eccentric outer circle of the present invention is as follows: 1. Composition of vehicle fixture As attached Figure 5 Shown: The vehicle clamp consists of an eccentric body and a clamping nut.

[0022] 2. Design of vehicle fixture Since the workpiece is long, only the left end face of the workpiece and the eccentric inner hole φD1 are used. +0.036 0 positioning will cause the eccentric distance between the eccentric outer circle and the concentric outer circle to be erroneous or angularly offset, and the accuracy requirement of L3±0.05 cannot be guaranteed. In order to ensure the accuracy requirement of L3±0.05, the designed vehicle fixture uses two short cylindrical outer circles (the two short cylindrical outer circles here refer to the third and fifth cylinders respectively) and one end face for positioning, but this design scheme leads to over-positioning. In order to eliminate over-positioning and ensure the accurate position of the eccentricity, the outer circle surface (the third cylinder) with an eccentricity of φd7 with the processed outer circle is positioned with a chamfered pin outer circle structure, as shown in the attached figure. Figure 5 DD section view is attached Figure 6 As shown in the figure, the outer cylindrical surface of φd6, which is concentric with the outer circle to be processed, continues to use the cylindrical surface structure for positioning, as shown in the figure. Figure 5 shown.

[0023] 3. Impact of Over-positioning When over-positioning occurs in the fixture design, interference will occur between the positioning support points that repeatedly restrict the same degree of freedom, resulting in unstable positioning, damage to positioning accuracy, deformation of the workpiece or positioning element, and even a situation where some workpieces cannot be installed.

[0024] 4. Positioning principle of chamfering pin In the design of machine tool fixtures, chamfered pins are generally used in the "one face, two pins" positioning method, and cylindrical pins are used in conjunction with chamfered pins. In the present invention, in order to increase the gap in the direction of the centerline of the two pins and avoid over-positioning, the second pin φd7, that is, the part that touches the workpiece hole wall in the eccentric direction, is eliminated, thus forming a chamfered pin structure. Only a portion of the left and right cylindrical surfaces are left. At this time, the size of the chamfered pin in the long axis direction is equal to φd7, and is perpendicular to the centerline of the two holes, that is, perpendicular to the eccentricity direction. The short axis direction is smaller than φd7, which prevents the second pin φd7 from contacting the hole wall in the direction of the centerline of the two holes, eliminating the adverse effects of over-positioning.

[0025] In short, the use of the chamfered pin structure design eliminates the occurrence of over-positioning and better ensures the precise position of the eccentricity between the eccentric circle and the concentric circle; at the same time, it also ensures that the rotation center of the lathe spindle coincides with the center of the outer circle to be machined on the workpiece, solving the problems of alignment, clamping and positioning when machining eccentric outer circles on ordinary lathes.

[0026] The following is an implementation method of the present invention when it is specifically applied: 1) When machining an eccentric outer circle, first use a four-jaw chuck to clamp the lathe fixture, and use a dial to align the C surface on the fixture and φd6 -0.007 -0.020 The outer circle of the watch should be less than 0.01mm; 2) Install the workpiece onto the eccentric body of the lathe fixture and use the C surface, φd6 -0.007 -0.020 Outer circle, and φd7 -0.010 -0.029 Diamond shaped positioning outer circle positioning; 3) Connect the clamping nut with the M120×3 external thread on the eccentric body through the step surface on the outer circle of the workpiece φd3, and tighten the nut so that the left end face of the workpiece is close to the C surface of the eccentric body to clamp the workpiece; 4) Check the inner hole φD1 of the workpiece by dialing +0.036 0, the table jump is less than 0.01mm; 5) Use the center point to directly support the center hole of the eccentric body on the lathe fixture. As the lathe spindle rotates, the rotation center of the lathe spindle coincides with the center of the outer circle to be machined on the workpiece, and the workpiece can be machined.

[0027] Technical innovations of the present invention: 1. By designing a lathe fixture, the workpiece is guaranteed to have a clamping and positioning reference. After calibrating the lathe fixture once, multiple workpieces can be processed without the need to calibrate the workpiece repeatedly. This greatly improves the processing efficiency of the product, ensures the processing accuracy of the product, and solves the problem of clamping, aligning and positioning when processing eccentric external cylindrical workpieces; 2. Positioning by a chamfered pin can not only accurately ensure the angular position of the two positioning holes of the workpiece, but also eliminate over-positioning and accurately ensure the precise position of the eccentric outer circle and the concentric outer circle eccentricity.

Claims

1. A vehicle clamp capable of improving eccentricity accuracy, characterized in that: It comprises an eccentric body (1) and a locking nut (2); the eccentric body (1) comprises a first, a second, a third, a fourth and a fifth cylinder connected in sequence, wherein the second cylinder has the largest outer diameter, the third cylinder is coaxial with the second cylinder, the first cylinder, the fourth cylinder and the fifth cylinder are coaxial and have the same eccentricity as the second cylinder, and the eccentricity is the same as the eccentricity of the workpiece to be processed; the outer diameters of the third cylinder, the fourth cylinder and the fifth cylinder decrease in sequence, and the outer circumference of the second cylinder is provided with an external thread; the end face where the second cylinder is connected to the third cylinder serves as a C face that is in close contact with the workpiece to be processed; the inner diameter of the eccentric outer circle of the fifth cylinder matches the inner diameter of the workpiece to be processed, the end face of the fifth cylinder is provided with a center hole, and the inner diameter of the third cylinder matches the inner diameter of the workpiece to be processed; An inwardly contracted convex edge is provided at one end of the clamping nut (2), and an internal thread matching the second cylinder is formed on the inner wall of the clamping nut (2).

2. A vehicle clamp capable of improving eccentricity accuracy as claimed in claim 1, characterized in that: The third cylinder adopts a chamfered pin structure.

3. A vehicle clamp capable of improving eccentricity accuracy as claimed in claim 2, characterized in that: The outer diameter of the third cylinder is φd7, and the portion of the third cylinder that hits the inner wall of the workpiece to be processed in the eccentric direction is eliminated, leaving a portion of the cylindrical surface perpendicular to the eccentric distance direction to form a chamfered pin structure.

4. A vehicle clamp capable of improving eccentricity accuracy as claimed in claim 3, characterized in that: The cross section of the third cylinder is a diamond structure, and the center line of the two sides perpendicular to the eccentricity direction is the major axis of the chamfered pin, which is equal to φd7, and the center line of the two sides parallel to the eccentricity direction is the minor axis of the chamfered pin, which is less than φd7; the outer diameter of the fifth cylinder is φd6.

5. A processing method capable of improving eccentricity accuracy, implemented by using the vehicle clamp according to claim 4, characterized in that: The steps include: 1) When machining an eccentric outer circle, first use a four-jaw chuck to clamp the lathe fixture, and use a dial to align the C surface on the lathe fixture and the outer circle of φd6, so that the dial runout is less than 0.01mm; 2) The workpiece to be processed is mounted on the eccentric body (1) of the lathe fixture, and is positioned using the C surface, the φd6 outer circle and the positioning outer circle of the φd7 diamond structure of the lathe fixture; 3) Connect the clamping nut (2) with the external thread on the eccentric body through the step surface on the outer circle of the workpiece φd3 to be processed, and tighten the clamping nut (2) so that the left end face of the workpiece to be processed is close to the C surface of the eccentric body, so that the workpiece can be clamped; 4) Check the inner hole φD1 of the workpiece with a meter, and the meter jump is less than 0.01mm; 5) Use the center point to directly press against the center hole of the eccentric body (1) on the lathe fixture. As the lathe spindle rotates, the rotation center of the lathe spindle coincides with the center of the outer circle to be machined of the workpiece, and the workpiece can be machined.

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