CN113579272A

CN113579272A - Arc groove turning tool and design method thereof

Info

Publication number: CN113579272A
Application number: CN202110886320.1A
Authority: CN
Inventors: 李炳林; 王洪; 李本杰; 郑华林; 郭骏宇; 郭亮
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2021-08-03
Filing date: 2021-08-03
Publication date: 2021-11-02

Abstract

The invention discloses a circular arc groove turning tool and a design method thereof. The cutting edge of the arc groove turning tool is composed of two asymmetric reducing arc edges. The design method comprises the steps of firstly, calculating an over-cut area between a fitting processing envelope line of a cutter and a final contour line of a part through the initial radius of the contour of the arc edge of the turning tool and the planning of the cutter path, determining the optimal processing area of the arc edge of the cutter, and then locally correcting the arc cutting edge of the turning tool according to the contour line of the part. In order to enhance the strength structure of the cutter, the size between the cutting part of the blade and the cutter body is gradually increased in two directions in simultaneous and alternate turns according to various constraint limits. The blade can also be designed into a single-edge structure, a double-edge structure and a three-edge structure. The invention can realize the fitting processing and the forming processing of the complex arc groove by using the same cutter, improve the processing precision, reduce the cutter cost and the like.

Description

Arc groove turning tool and design method thereof

Technical Field

The invention relates to the field of special cutters for machining, in particular to a special turning cutter structure for a composite arc groove and a design method thereof, which can provide technical support for machining and manufacturing of arc groove parts with complex shapes and the like.

Background

In the fields of petroleum equipment, automobiles, power generation equipment and the like, arc groove parts with complex shapes are often required to be machined, and the machining of the key parts requires the design and customization of special forming turning tools. The blade form of the blade is calculated according to the part contour, and can be completely consistent with the part contour or not. The design and manufacture of the arc groove forming turning tool are complex, the contour dimension of a part needs to be considered in the design process, the feed route, the cutting amount and the like need to be considered, the accurate and consistent part contour can be obtained, and the interchangeability of the part is ensured. Therefore, the invention provides a design method of an asymmetric reducing arc groove turning tool, which has very important significance for improving the machining precision of a composite arc groove with a small arc radius.

Disclosure of Invention

The invention aims to provide a turning tool for an arc groove and a design method thereof, and in the processing of arc groove parts, a mixed processing mode of high-precision fitting turning and forming turning of composite arc groove parts can be realized through the special design of an asymmetric variable-diameter arc tool.

The invention is realized by the following technical scheme:

the invention provides a turning tool design method for machining an arc groove, which is characterized by comprising the following steps of: s1, determining the initial radius of the turning tool circular arc blade profile according to the radius of the part circular arc groove; s2, designing and calculating a reasonable cutter path according to the contour line of the arc groove of the part and the contour radius of the arc edge of the cutter; s3, determining an over-cutting area between a tool fitting envelope line and a final part contour line according to the feed path and the contour radius of the arc cutting edge of the tool, and locally correcting the arc cutting edge of the turning tool; and S4, carrying out strength and multi-index design on the asymmetric variable-diameter arc turning tool.

Specifically, in the step S1, the arc groove is formed by sequentially connecting a slant line (1), an arc (2) and a straight line (3) in a tangent manner, and the radius of the arc edge of the tool is selected to be #3 according to the radius #2 of the arc (2), preferably, #2- #3 is not less than 0.2 mm.

Specifically, in step S2, an equidistant curve (a '→ B' → C '→ D') of the part contour line is calculated from the intersection (A, B, C, D) of the part arc groove and the center O as an initial tool path. In order to improve the accuracy of fitting the large arc groove workpiece along the equidistant curve by the small arc edge turning tool, preferably, the path of the tool is lengthened, the center O of the arc segment (B '→ C') of the tool path is shifted to the non-machining side by a certain distance #4, the shifted center is O ', the shifted center O' is used as the center of a circle, the radius #2- #3+ #4 is used as the radius to make an arc (E '→ F'), the modified tool path replaces the small arc (E '→ C') of the original equidistant curve by the extended large arc (E '→ F'), and the extended arc segment (E '→ F') and the original equidistant arc segment (B '→ E' → C ') are tangent to E'.

Further, in step S2, since the arc blade turning tool has good rigidity in the X direction and poor rigidity in the Z direction, the optimum cutting area of the arc blade turning tool is #5, preferably, #5 is not greater than 120 °. According to the optimal cutting area #5 of the arc cutter, the central offset size #4 of the arc path of the cutter is determined, the critical point E of the arc edge of the turning tool is ensured to be in the optimal cutting area, and the number of feed steps of an extended large arc segment (E '→ F') in the arc path of the cutter is satisfied: the step number is more than or equal to 100 steps so as to improve the precision of fitting processing.

Preferably, in step S2, in order to avoid the over-cutting of the tool, the tool path of the linear (3) machining segment of the part is defined as a straight line (F '→ G'). In order to avoid the over-cutting of a straight edge D of an arc groove and the excessive cutting load during cutting, a cutter path is planned to be a diagonal line (J ' → I ') and an arc (I ' → H '), a radius #3 of a cutter arc edge is a radius with a point D as a center of a circle and is planned to be an arc section (I ' → H ') of the cutter path, and the arc section (I ' → H ') of the cutter path and the straight line section (F ' → G ') of the cutter path intersect at the point H '. To avoid overcutting, the cutting-in segment from point H 'to point G' is also designed as a straight line (H '→ G'), the angle of the cutting-in tool path segment (J '→ I') being designed to be #6, preferably, #6 ≧ 30 °.

Specifically, in step S3, an envelope of the tool is designed and calculated based on the tool path planned above and the preliminarily selected radius of the tool circular edge, an over-cut region (a hatched region with a boundary of E → C → D) between the tool envelope and the final contour of the part and the critical point E are determined, and the final contour boundary (E → C boundary) of the part where no over-cut occurs is corrected as the contour line (E → F) of the local part of the tool circular edge.

Specifically, the invention provides a turning tool for an arc groove, which is characterized in that: the final cutting edge profile of circular arc sword cutter is asymmetric reducing circular arc sword cutter, and the circular arc sword is connected gradually by straight line (5), circular arc (6), circular arc (7) and straight line (8) and constitutes, and wherein the radius #3 of circular arc (6) and the radius #7 inequality of circular arc (7), and circular arc (6) are connected in point E with circular arc (7), and the centre of a circle of the relative circular arc (6) in the centre of a circle of circular arc (7) is to right side horizontal migration distance and is:

further, the invention provides a turning tool for the arc groove, which is characterized in that: the arc groove cutter only takes part in cutting of the half-edge arc (6) and the arc (7), and the rest are non-cutting areas. The cutting area is an asymmetric reducing area formed by an arc blade (6) and an arc blade (7), and the non-cutting area is an area formed by a straight line (5) and a straight line (8).

Specifically, included angles between straight line segments (5) and (8) of the cutter and the X direction are as follows: #8 is more than or equal to 2 degrees to avoid the contact with the workpiece when the cutter cuts the contour line (3) of the part, and the over-cutting and the friction are generated. Further, included angles between straight line segments (1) and (5) of the cutter and the X direction are as follows: and #8 is less than or equal to 5 degrees, and the front angle #9#, the rear angle #10 and the transition angle #11 of the cutter take smaller values, preferably, the front angle #9 is less than or equal to 5 degrees, the rear angle #10 is less than or equal to 5 degrees, and the transition angle #11 is less than or equal to 30 degrees, so that the fracture caused by too low strength and too high cutting load of the cutting part of the blade is avoided.

Preferably, in order to increase the rigidity of the blade against the cutting force, the local stress concentration is reduced, and the vibration and the breakage generated when the cutter cuts are avoided. The size of the cutter body part of the cutter is gradually increased from the height Y direction and the width Z direction through an arc surface or an inclined surface. The size of the cutter body can be gradually increased in the width direction and the height direction simultaneously according to processing limitation and design requirements, and the cutter body can also be alternately and repeatedly kept in the same direction and gradually increased in the other direction. The blade sizes #12 and #17 and #15 and #20 increase in both height and width directions, the blade sizes #13 and #18 are constant in the width direction while increasing in the height direction by means of the inclined surface, and the blade sizes #14 and #19 are constant in the height direction while increasing in the width direction by means of the inclined surface.

Preferably, the insert can be designed into a single-edge, indexable point-symmetrically arranged double-edge structure and a triangular arranged three-edge structure. In order to enhance the structural strength and rigidity of the triangular cutter body without reducing the strength of the cutting portion of the blade, the cutting portion of the triangular blade is connected with the cutter body by increasing the size of the transition portion through increasing the angle #13 without changing the angle #11, and the blade clamping portion connects the cutting portions of three edges together through a triangular structure.

The invention has the following advantages and beneficial effects:

1. the method for designing the turning tool of the arc groove can prolong the path of the turning tool and improve the fitting machining precision of the arc groove. When the diameter of the arc groove is smaller, the arc lathe tool with smaller radius is used for fitting processing, and the precision of the fitting processing is difficult to guarantee because the equidistant feed route deduced from the part contour line is shorter. The invention provides a method for prolonging the path of a cutter, which prolongs the path of the cutter by deviating the arc section of the path of the cutter from the original center by a certain distance and replacing the arc section of the original path with a larger and longer arc section, increases the number of feed steps by correcting the prolonged path of the cutter, and improves the accuracy of arc interpolation fitting processing of an arc groove.

2. The method for designing the turning tool for the arc groove can simultaneously realize the fitting processing and the forming processing of the arc groove by using the same asymmetric reducing arc blade turning tool. When the part of the cutter arc blade with the radius smaller than the radius of the part arc contour is in contact cutting with a workpiece, the cutter path is equidistant to the contour line of the part arc groove, and the arc groove is machined by fitting the arc blade turning tool with the smaller radius. When the part of the cutter arc blade with the radius equal to the radius of the part arc outline is in contact cutting with a workpiece, the outline of the blade is the same as the outline of the part arc groove, the arc groove is machined by using the arc blade forming turning tool, the forming turning is completed by one-time transverse feeding, and the machining precision is high. Meanwhile, for the whole blade, only part of the arc edge is in contact with a workpiece to participate in forming and turning, so that the cutting load is small, the vibration is not easy to generate, and the machining precision is ensured. The asymmetric reducing arc blade turning tool improves the application range and functions of the arc groove tool.

3. The special turning tool for the arc groove can be designed into a single blade, a double blade or a three-blade. The multi-transposition arc groove turning tool improves the strength of the tool body through the structure optimization design, and can be designed into a single-blade, double-blade or multi-blade form. When one cutting edge is worn, the cutting edge can be turned and then continuously used, so that the replacement time of the cutting edge is reduced, the machining efficiency is improved, the use of cutter body materials is reduced, and the production cost of the cutter is reduced.

Drawings

FIG. 1 is a drawing of a part of a processed arc groove

FIG. 2 is a design calculation chart of a turning tool for arc grooves

FIG. 3 is a design drawing of a single-edge arc groove turning tool

FIG. 4 is a design drawing of a double-edged and triple-edged turning tool for arc grooving

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not used as limitations of the present invention.

Example 1

The present invention will be described with reference to fig. 1 and 2, in an embodiment 1 of a special turning tool for an arc groove.

Aiming at the part diagram of the composite arc groove shown in the attached figure 1, the geometric relationship among the part profile, the radius of the arc blade of the cutter and the cutter path is analyzed. FIG. 2 is a schematic diagram of the design calculation of the special tool for machining the arc groove workpiece in FIG. 1, wherein the composite arc groove is formed by respectively tangency of two straight lines (1) and (3) with an arc (2). Taking the following arc groove parameters as examples, #1 is 30 °, #2 is 1.8 mm. Firstly, according to the radius #2 of the arc groove of the part being 1.8mm, the radius #3 of the arc edge contour of the turning tool being 1.5mm is preliminarily selected, and the requirements that #2- #3 being 0.3mm is more than or equal to 0.2mm are met.

In the second step, an equidistant curve (a '→ B' → C '→ D') of the part contour line is calculated as an initial tool path based on the contour line (a → B → C → D) of the part arc groove and the tool arc edge radius #3 ═ 1.5 mm. Correcting an initial cutter path (B '→ C') of the arc segment (B → C ') of the machined part, translating a center O of the arc segment (B' → C ') of the initial cutter path in the X direction to 0.2mm, using an arc (E' → F ') with a radius of 0.5mm as a radius of #2- #3+ #4 as the center O' after the translation as a cutter path of the arc segment (B → C) of the machined part after the correction, and enabling the corrected cutter path and the original equidistant arc segment (B '→ E' → C ') to be tangent to E'. The cutter path of the whole circular arc groove is as follows: (L '→ G' → F '→ E' → B '→ A' → N '→ M')

And thirdly, determining the critical point E position of the excessive cutting between the envelope line of the cutter and the final contour line of the part according to the corrected cutter path (B ' → E ' → C ') and the primarily selected cutter circular arc edge radius #3 ═ 1.5mm, wherein the regions except the boundary E → C → D are all excessive cutting regions. The boundary of the final contour (E → C) of the part is used as the contour line (E → F) of the part of the tool circular edge.

According to the asymmetric reducing tool designed in the steps, the final cutting edge profile is formed by sequentially connecting a straight line (5), an arc (6), an arc (7) and a straight line (8), the radius #3 of the arc (6) is 1.5mm, the radius #7 of the arc (7) is 1.8mm, and the position of a point E where the arc (6) is connected with the arc (7) is as follows: the included angle of EF 'relative to CF' is 55 degrees, the center of the circular arc (7) is horizontally shifted to the left side relative to the center of the circular arc (6)

Example 2

This embodiment differs from example 1 in that the tool path cut is not a straight line, but rather a circular arc. The cutting edge of the tool is not a full edge, but a half edge, and the best cutting area is used as much as possible when the half edge tool participates in the cutting process. The method comprises the following specific steps:

in order to avoid the cutter from generating overcut, the cutter path of the linear (3) processing section of the part is planned to be a straight line (F '→ G'). In order to avoid over-cutting of the straight edge D of the arc groove and excessive cutting load during cutting, the cutting tool path (L '→ G' → F ') in example 1 was modified, the tool path was planned to be an oblique line (J' → I ') and an arc (I' → H '), the tool path cut into and machined the straight edge D of the arc groove was planned to be an arc (I' → H ') with the point D as the center and the radius #3 ═ 1.5mm, the straight line segment (F' → G ') extending the tool path and the arc (I' → H ') of the tool path were intersected at the point H', the tool path (J '→ I' → H '→ G' → F ') was taken as the modified tool cutting path, wherein the tool path (K' → J ') was a fast-moving tool path, the tool path (J' → I ') was started, and the tool path (I' → H '→ G') was taken as the arc D of the cutting tool path, the section of the cutter path (G '→ F') is a straight line section (3) for processing the arc groove. When the cutting is started, the angle #6 of the oblique line (J '→ I') segment of the tool path becomes 45 °.

Because the rigidity of the arc edge turning tool in the X direction is good, and the rigidity of the arc edge turning tool in the Z direction is poor, the optimal cutting area #5 of the arc edge turning tool is selected to be 100 degrees. According to the defined optimal cutting area of the circular arc tool, checking the position of a critical point E at which the central offset #4 of the circular arc path of the tool is equal to 0.2 mm: the included angle of EF ' relative to CF ' is 55 degrees, and the EF ' is positioned in the optimum cutting area, and the corrected circular arc section of the cutter path is reasonable. In order to reduce the grinding workload of the cutting edge of the cutter, the arc groove cutter only involves the half-edge arc (6) and the half-edge arc (7) to cut, and the straight line (5) and the straight line (8) are non-cutting areas in the machining process. According to the corrected tool path and half edge characteristics, the straight line (8) of the tool cutting edge is designed to start from C.

Example 3

The difference between the present embodiment and examples 1 and 2 is that the cutting part and the body part of the tool increase the strength and rigidity of the tool in various ways, reduce local stress concentration, and avoid vibration and fracture when the tool is used for cutting. This is explained in detail with reference to fig. 3.

The included angle between the straight line segments (5) and (8) of the cutter and the X direction is selected to be small #8 which is 3 degrees, so that the contact between the cutter and a workpiece when the contour line (3) of the cutter cutting part is cut can be avoided, the over-cutting and the friction are generated, the strength of the cutting part of the blade can be increased, and the excessive breaking of the cutting force is avoided. The rake angle #9, the relief angle #10, and the transition angle #11 of the cutting portion of the tool are all smaller than 2 °, 3 °, and 30 °, enhancing the ability of the insert to resist deformation and fracture under cutting loads.

The size of the cutter body part of the cutter is gradually increased from the height Y direction and the width Z direction through an arc surface or an inclined surface, and the sizes #12 and #17 of the cutter bodies are simultaneously increased from the height direction and the width direction through the arc surface, so that the stress concentration and the breakage of the weakest part are avoided. The blade body sizes #13 and #18 are constant in the width direction and gradually increase in the height direction by the inclined surface, and the blade body sizes #14 and #19 are constant in the height direction and gradually increase in the width direction by the inclined surface. The cutter body sizes #15 and #20 are gradually increased while passing through the inclined plane in the height and width directions.

Example 4

The difference between this embodiment and example 3 is that in order to reduce the cost of the blade and improve the processing efficiency, the blade is designed into a double-edge and multi-edge structure, which is specifically described with reference to fig. 4.

The cutter body of the cutter is designed into a double-blade capable of being turned, and is not in plane symmetrical arrangement but in point symmetrical arrangement. The cutter can also be designed into a three-edge structural form in triangular arrangement, in order to not reduce the strength of the cutting part of the cutter, the angle #11 of the cutting part of the triangular cutter is not changed, the angle #13 and the size of the transition part in the height direction are increased by connecting the cutter body, and the cutter clamping part is in a triangular structure, so that the clamping reliability is improved.

Claims

1. A circular arc groove turning tool and a design method thereof are characterized in that the design method comprises the following steps: s1, determining the initial radius of the turning tool circular arc blade profile according to the radius of the part circular arc groove; s2, designing and calculating a reasonable cutter path according to the contour line of the arc groove of the part and the contour radius of the arc edge of the cutter; s3, determining an over-cutting area between a tool fitting envelope line and a final part contour line according to the feed path and the contour radius of the arc cutting edge of the tool, and locally correcting the arc cutting edge of the turning tool; and S4, carrying out strength and multi-index design on the asymmetric variable-diameter arc turning tool.

2. The design method of the arc grooving turning tool according to claim 1, wherein: in the step S1, the arc groove is an asymmetric composite arc groove formed by sequentially and tangentially connecting an oblique line (1), an arc (2) and a straight line (3), and the radius of the arc edge of the cutter is selected to be #3 according to the radius #2 of the arc (2), preferably, #2- #3 is not less than 0.2 mm.

3. The design method of the arc grooving turning tool according to claim 1, wherein: in the step S2, an equidistant curve (a '→ B' → C '→ D') of the part contour line is calculated as an initial tool path from the intersection (A, B, C, D) of the part arc groove and the center O; preferably, in order to improve the fitting accuracy of the small arc lathe tool to the large arc groove, the center O of the arc segment (B '→ C') of the tool path is shifted to the non-machining side by a certain distance #4, the tool path is lengthened, the center after the shift is O ', the arc (E' → F ') is made with the center O' of the shift and the radius #2- #3+ #4 as the center, and the revised tool path is replaced by the lengthened large arc (E '→ F') instead of the small arc (E '→ C') of the original equidistant curve.

4. The design method of the arc grooving turning tool according to claim 3, wherein: in the step S2, because the arc edge turning tool has good rigidity in the X direction and poor rigidity in the Z direction, it is determined that the optimum cutting area of the arc edge turning tool is #5, preferably, #5 is not more than 120 °; the size #4 of the central offset of the tool arc path is determined according to the optimal cutting area #5 of the arc tool, so that the critical point E of the turning tool arc edge is ensured to be in the optimal cutting area, and the number of cutting steps of an extended large arc segment (E '→ F') in the tool path is satisfied: the step number is more than or equal to 100 steps so as to improve the precision of fitting processing.

5. A method for designing a circular arc grooving tool as claimed in claim 1 and claim 3, wherein: in step S3, an envelope of the tool is designed and calculated based on the planned tool path and the initially selected tool radius #2, an over-cut region (a hatching region where E → C → D is a boundary) and a critical point E between the tool envelope and the final contour of the part are determined, and the final contour boundary (E → C boundary) of the part where no over-cut occurs is used as a correction for the contour line (E → F) of the local part of the tool edge.

6. The arc grooving turning tool and the design method thereof according to claims 1 to 5, wherein: the final cutting edge profile of circular arc sword cutter is asymmetric reducing circular arc sword cutter, and the circular arc sword is connected gradually by straight line (5), circular arc (6), circular arc (7) and straight line (8) and constitutes, and wherein the radius #3 of circular arc (6) and the radius #7 inequality of circular arc (7), and circular arc (6) are used for fitting processing, and circular arc (7) are used for taking shape processing, and the centre of a circle of the relative circular arc (6) in the centre of a circle of circular arc (7) is to right side horizontal migration distance and is:

7. the turning tool for arc grooving and the design method thereof according to claim 3 and claim 6, wherein: preferably, the arc groove cutter only participates in cutting by a half-edge arc (6) and an arc (7), and the rest is a non-cutting area; the cutting area is an asymmetric reducing area formed by an arc blade (6) and an arc blade (7), and the non-cutting area is an area formed by a straight line (5) and a straight line (8).

8. The turning tool for turning a circular arc groove and the design method thereof according to claim 6 and claim 7, wherein: included angles between straight line segments (5) and (8) of the cutter and the X direction are as follows: #8 is more than or equal to 2 degrees to avoid the contact with the workpiece when the cutter cuts the contour line (3) of the part, and the over-cutting and the friction are generated; further, included angles between straight line segments (1) and (5) of the cutter and the X direction are as follows: and #8 is less than or equal to 5 degrees, and the front angle #9#, the rear angle #10 and the transition angle #11 of the cutter take smaller values, preferably, the front angle #9 is less than or equal to 5 degrees, the rear angle #10 is less than or equal to 5 degrees, and the transition angle #11 is less than or equal to 30 degrees, so that the fracture caused by too low strength and too high cutting load of the cutting part of the blade is avoided.

9. The circular arc grooving tool and the design method thereof according to claim 6, wherein: the size of the cutter body part of the cutter is gradually increased from the height Y direction and the width Z direction through an arc surface or an inclined surface; the size of the cutter body can be gradually increased in the width direction and the height direction simultaneously according to processing limitation and design requirements, and the cutter body can also be alternately and repeatedly kept in the same direction and gradually increased in the other direction so as to enhance the structural strength of the cutter blade; the cutter body sizes #12 and #17 and #15 and #20 increase in height and width directions simultaneously, the cutter body sizes #13 and #18 are constant in width direction and gradually increase in height direction through the inclined plane, and the cutter body sizes #14 and #19 are constant in height direction and gradually increase in width direction through the inclined plane.

10. The turning tool for the arc groove and the design method thereof according to claims 1 to 9, wherein: the blade can be designed into a single-edge, double-edge structure which can be rotationally and point-symmetrically arranged and a three-edge structure which is triangularly arranged; in order to enhance the structural strength and rigidity of the triangular cutter body without reducing the strength of the cutting portion of the blade, the cutting portion of the triangular blade is connected with the cutter body by increasing the size of the transition portion through increasing the angle #13 without changing the angle #11, and the blade clamping portion connects the cutting portions of three edges together through a triangular structure.