Fine cutting tooth broach and machining process thereof

Abstract

The fine cutting tooth broach comprises a broach body, calibration teeth, rough cutting teeth and fine cutting teeth, fixing screw holes are formed in the front end and the rear end of the surface of the broach body correspondingly, and evenly-distributed positioning screw holes are formed in the bottom of the broach body; the broaching tool comprises a broaching tool body, the upper surface of the broaching tool body is sequentially provided with a plurality of calibration teeth, rough cutting teeth and fine cutting teeth from left to right, the calibration teeth are equal in tooth height, the tooth heights of the rough cutting teeth are gradually increased, the tooth heights of the fine cutting teeth are equal, and the front end and the rear end of the broaching tool body are each provided with a guide part. According to the broach, the fixing screw holes are formed in the front end and the rear end of the surface of the broach body correspondingly, the positioning screw holes which are evenly distributed are formed in the bottom of the broach body in a matched mode, the broach body is fixedly installed on the surface of a numerical control machine tool conveniently, accurate cutting machining can be conducted on parts conveniently by arranging the accurate cutting teeth which are evenly distributed on the surface of the broach body, and machining efficiency is improved. And the production precision of parts is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal cutting tool manufacturing, in particular to a precision cutting tooth broach and a processing technology thereof. Background Art

[0002] A broach is a forming tool used for broaching. There are multiple rows of teeth on the surface of the tool, and the size and shape of each row of teeth increase and change from the cutting end to the cutting end. When the broach is broaching, each tooth cuts a certain thickness of metal from the workpiece, and finally obtains the required size and shape. Broaches are often used in batch and mass production to process round holes, spline holes, keyways, planes and forming surfaces, etc., with high productivity. According to the different parts of the processing surface, broaches are divided into internal broaches and external broaches; according to the different force modes during work, they are divided into broaches and pusher tools. Pusher tools are often used to calibrate the molded holes after heat treatment.

[0003] A vertical broaching machine is a metal cutting machine that can be used to process keyway-type workpieces. When the vertical broaching machine is processing, the workpiece is generally stationary, and the broach moves linearly with the slide. The main body of the broaches on the market has some defects in production, which are mainly manifested in the low manufacturing precision of the broach body itself, the long manufacturing cycle of the cutter teeth, the poor wear resistance of the cutter teeth, and the reduced processing quality of the workpiece surface. For this reason, a precision cutting tooth broach and its processing technology are proposed. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies in the prior art, the present invention provides a precision cutting tooth broach and a processing technology thereof, which solves the problems that the existing broach body itself has low manufacturing precision, a long production cycle, and poor wear resistance of the teeth.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a fine-cutting tooth broach, comprising a broach body, calibration teeth, rough-cutting teeth and fine-cutting teeth, the front and rear ends of the surface of the broach body are respectively provided with fixing screw holes, the bottom of the broach body is provided with evenly distributed positioning screw holes, the upper surface of the broach body is provided with calibration teeth, rough-cutting teeth and fine-cutting teeth from left to right in sequence, the calibration teeth include a plurality of teeth with equal tooth heights, the tooth height of the rough-cutting teeth gradually increases, the tooth heights of the fine-cutting teeth are equal to each other, and the front and rear ends of the broach body are both provided with guide portions.

[0008] As a further preferred embodiment of the present invention, the tooth spacing between the finishing teeth is 6.986 mm, a chip groove is provided between the finishing teeth, the radius of the bottom of the chip groove is 1.6 mm, and the angle between the inner wall of the chip groove and the front tooth is 50°.

[0009] As a further preferred embodiment of the present invention, the surface of the calibration tooth is provided with chip dividing grooves, and the chip dividing grooves are staggered in the form of two in front and one in the back.

[0010] As a further preferred embodiment of the present invention, guiding slopes are respectively provided at the edges on both sides of the guiding portion, and the guiding slopes are inclined at 50°.

[0011] A precision cutting tooth broach processing technology, comprising:

[0012] (1) Blanking: Use a sawing machine to cut high-speed steel bars for processing the broach body 1, and retain a certain processing allowance to facilitate subsequent processing of the blank;

[0013] (2) Lathe processing: Use a lathe to process the ends and surfaces of the blanks, remove the black skin on the surface of the blanks and the burrs from sawing at the ends, improve the size accuracy of the blanks, and use a drill to open fixing holes at both ends to facilitate subsequent processing to fix the burrs;

[0014] (3) Milling machine processing: The blank is mounted on a precision chuck and processed using a CNC milling machine to remove excess material from the surface of the blank to obtain a spare part that conforms to the shape of the broach body; and positioning holes are evenly distributed at the bottom of the blank, with a spacing of 130 mm.

[0015] (4) Tapping: Use a tapping machine to tap the fixing holes and positioning holes for positioning during tooth cutting, improve the convenience of fixed installation, and ensure the accuracy of tooth processing on the surface of the broach body;

[0016] (5) Wire cutting rough processing: Use CNC electric spark wire cutting machine to cut the surface of spare parts, wire cutting rough processing broach body surface calibration teeth, rough cutting teeth and fine cutting teeth, wire cutting tooth shape is based on the positioning hole;

[0017] (6) Heat treatment: The broach body 1 after the tooth profile processing is placed in a vacuum furnace for vacuum quenching and vacuum tempering treatment, so as to obtain good comprehensive mechanical properties and small workpiece deformation. After the heat treatment, the spacing between the positioning holes is 129.7 mm, and the hardness after quenching is 64-65 HRC;

[0018] (7) Cold treatment: placing the broach body 1 after the heat treatment in a liquid nitrogen cooling box for low-temperature aging treatment to shape the internal structure of the material and thus improve the stability of the cutter head size;

[0019] (8) Wire cutting finishing: Use precision CNC wire-cutting machine tools and the four-axis four-linkage CNC wire-cutting function of precision CNC wire-cutting machine tools to fine-cut the fine-cut teeth and chip grooves with inclinations. The fine-cutting of the fine-cut teeth and chip grooves is completed in one clamping to improve the accuracy of the broach body processing and avoid the clearance caused by repeated clamping.

[0020] (9) Tooth profile fine grinding: Use a precision cylindrical grinder to install the broach body on a positioning fixture, and use the grinder to perform precision grinding on the surface of the teeth to ensure the shape and position tolerances of each tooth in the same group.

[0021] As a further preferred embodiment of the present invention, the fixing hole and the positioning hole have the same size, the diameter of the fixing hole is 6 mm, and the depth of the fixing hole is 12-15 mm.

[0022] As a further preferred embodiment of the present invention, the quenching temperature during the vacuum quenching treatment is 1180° C., the temperature of the vacuum tempering is 175-350° C., and the tempering time is about 2 hours.

[0023] As a further preferred embodiment of the present invention, the precision cylindrical grinder is divided into three grinding processing steps during grinding, namely, plane rough grinding, plane semi-finishing grinding and plane fine grinding, and cooling treatment is performed between the plane rough grinding, plane semi-finishing grinding and plane fine grinding processes.

[0024] (III) Beneficial effects

[0025] The present invention provides a precision cutting tooth broach and a processing technology thereof. It has the following beneficial effects:

[0026] 1. The present invention provides fixing screw holes at the front and rear ends of the surface of the broach body, respectively, and cooperates with the evenly distributed positioning screw holes at the bottom, so as to facilitate the fixing and installation of the broach body on the surface of a CNC machine tool. Evenly distributed precision cutting teeth are provided on the surface of the broach body, so as to facilitate precision cutting of parts and improve the production accuracy of parts.

[0027] 2. The present invention provides fixing holes and positioning holes at both ends and the bottom of the broach body, respectively, to facilitate positioning during processing, improve the accuracy of first cutting the tooth shape, and facilitate the installation of the broach body and the moving parts of the CNC broaching machine, thereby improving the structural strength of the broach body.

[0028] 3. The present invention makes the grains of the broach body finer by high-temperature quenching the broach body, while improving the uniformity of grain distribution, greatly improving the rigidity and strength of the fine-cut teeth on the surface of the broach body, and facilitating cutting of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1It is a schematic diagram of the side view structure of the fine cutting tooth broach of the present invention;

[0030] Figure 2 It is a schematic diagram of the top view of the structure of the precision cutting tooth broach of the present invention;

[0031] Figure 3 It is a schematic diagram of the local structure of the precision-cut teeth part of the present invention;

[0032] Figure 4 It is a schematic diagram of the tooth shape structure of the precision cutting tooth of the present invention;

[0033] Figure 5 It is a schematic diagram of the processing technology of the fine cutting tooth broach of the present invention.

[0034] In the figure: broach body -1, calibration teeth -2, rough cutting teeth -3, fine cutting teeth -4, fixing screw hole -5, positioning screw hole -6, guide part -7, chip accommodating groove -8, chip dividing groove -9, guide slope -10. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] See also Figure 1-5 The embodiment of the present invention provides a technical solution: a fine-cutting tooth broach, comprising a broach body 1, calibration teeth 2, rough-cutting teeth 3 and fine-cutting teeth 4, the front and rear ends of the surface of the broach body 1 are respectively provided with fixing screw holes 5, the bottom of the broach body 1 is provided with evenly distributed positioning screw holes 6, the upper surface of the broach body 1 is provided with calibration teeth 2, rough-cutting teeth 3 and fine-cutting teeth 4 from left to right, the calibration teeth 2 include a plurality of teeth with equal tooth heights, the tooth height of the rough-cutting teeth 3 gradually increases, the tooth heights of the fine-cutting teeth 4 are equal to each other, and the front and rear ends of the broach body 1 are provided with guide parts 7.

[0037] As a further improvement, the tooth spacing between the finishing teeth 4 is 6.986 mm, and a chip groove 8 is provided between the finishing teeth 4. The radius of the bottom of the chip groove 8 is 1.6 mm, and the angle between the inner wall of the chip groove 8 and the front tooth is 50°. By providing an arc-shaped chip groove 8 between the finishing teeth 4, it is convenient to curl and remove the chips in the pin pulling process, thereby improving the smoothness of chip removal and the accuracy of production processing.

[0038] As a further improvement, the surface of the calibration tooth 2 is provided with chip dividing grooves 9, and the chip dividing grooves 9 are staggered in the form of two in front and one in the back. By providing the surface of the calibration tooth 2 with two chip dividing grooves 9 distributed in the front and one in the back, it is convenient to reduce the width of the chips, avoid sticking to the tool, and improve the efficiency of chip removal.

[0039] As a further improvement, guide bevels 10 are respectively provided at the edges on both sides of the guide portion 7, and the guide bevels 10 are inclined at 50°. By providing inclined guide surfaces at the edges of the guide portion 7, the stability of the broach body and component parts is improved, and the broach body is prevented from tilting during processing.

[0040] A fine tooth cutting 4 broaching process, comprising:

[0041] (1) Blanking: Use a sawing machine to cut high-speed steel bars for processing the broach body 1, and retain a certain processing allowance to facilitate subsequent processing of the blank;

[0042] (2) Lathe processing: Use a lathe to process the ends and surfaces of the blanks, remove the black skin on the surface of the blanks and the burrs from sawing at the ends, improve the size accuracy of the blanks, and use a drill to open fixing holes at both ends to facilitate subsequent processing to fix the burrs;

[0043] (3) Milling machine processing: The blank is mounted on a precision chuck and processed using a CNC milling machine to remove excess material from the surface of the blank to obtain a spare part that conforms to the shape of the broach body; and positioning holes are evenly distributed at the bottom of the blank, with a spacing of 130 mm.

[0044] (4) Tapping: Use a tapping machine to tap the fixing holes and positioning holes for positioning during tooth cutting, improve the convenience of fixed installation, and ensure the accuracy of tooth processing on the surface of the broach body;

[0045] (5) Wire cutting rough processing: Use a CNC electric spark wire cutting machine to cut the surface of the spare part, and wire cut the calibration teeth 2, rough cutting teeth 3 and fine cutting teeth 4 on the surface of the broach body. The positioning hole is used as the reference when wire cutting the tooth shape;

[0046] (6) Heat treatment: The broach body 1 after the tooth profile processing is placed in a vacuum furnace for vacuum quenching and vacuum tempering treatment, so as to obtain good comprehensive mechanical properties and small workpiece deformation. After the heat treatment, the spacing between the positioning holes is 129.7 mm, and the hardness after quenching is 64-65 HRC;

[0047] (7) Cold treatment: placing the broach body 1 after the heat treatment in a liquid nitrogen cooling box for low-temperature aging treatment to shape the internal structure of the material and thus improve the stability of the cutter head size;

[0048] (8) Wire cutting finishing: Using a precision CNC wire-cutting machine tool, the four-axis four-linkage CNC wire-cutting function of the precision CNC wire-cutting machine tool is used to fine-cut the fine-cut teeth 4 and the chip grooves 8 with inclinations; the fine-cutting of the fine-cut teeth 4 and the chip grooves 8 is completed in one clamping to improve the accuracy of the broach body processing and avoid the clearance caused by repeated clamping;

[0049] (9) Tooth profile fine grinding: Use a precision cylindrical grinder to install the broach body on a positioning fixture, and use the grinder to perform precision grinding on the surface of the teeth to ensure the shape and position tolerances of each tooth in the same group.

[0050] According to a further improvement, the fixing hole and the positioning hole have the same size, the diameter of the fixing hole is 6 mm, and the depth of the fixing hole is 12-15 mm. By opening M6 fixing holes and positioning holes on the surface of the broach body, it is convenient to position the tool when processing the teeth, and it is also convenient to fix it on the surface of the machine tool during use, which facilitates disassembly, assembly and replacement.

[0051] As a further improvement, the quenching temperature during the vacuum quenching treatment is 1180°C, the vacuum tempering temperature is 175-350°C, and the tempering is about 2 hours. Through the high-temperature quenching at 1180°C, the quenched grain size reaches 10.5#, which greatly improves the uniformity of the quenched grain distribution.

[0052] According to further improvement, the grinding process of the precision cylindrical grinder is divided into three grinding process steps, namely, plane rough grinding, plane semi-finishing grinding and plane fine grinding. Cooling treatment is performed between the plane rough grinding, plane semi-finishing grinding and plane fine grinding processes to avoid overheating of the fine cutting teeth 4 on the surface of the broach body and affect the sharpness of the cutting edge, thereby increasing the service life of the fine cutting teeth 4.

[0053] The broach body 1, calibration teeth 2, rough cutting teeth 3, fine cutting teeth 4, fixing screw holes 5, positioning screw holes 6, guide parts 7, chip grooves 8, chip dividing grooves 9, and guide bevels 10 of the present invention are all universal standard parts or parts known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods. The problem solved by the present invention is that the broach bodies in the market have some defects in production, which are mainly manifested in the low manufacturing precision of the broach body itself, the long manufacturing cycle of the teeth, the poor wear resistance of the teeth, and the reduced The processing quality of the workpiece surface is improved. The present invention respectively opens fixing screw holes at the front and rear ends of the surface of the broach body, and opens evenly distributed positioning screw holes at the bottom, so that the broach body can be fixedly installed on the surface of a CNC machine tool. Evenly distributed fine cutting teeth are provided on the surface of the broach body, so that the fine cutting of parts is convenient and the production accuracy of parts is improved. High-temperature quenching of the broach body makes the grains of the broach body finer and the uniformity of grain distribution is improved, which greatly improves the rigidity and strength of the fine cutting teeth on the surface of the broach body and facilitates the cutting of parts.

[0054] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0055] In addition, the terms "first", "second", "third" and "fourth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first", "second", "third" and "fourth" may explicitly or implicitly include at least one of such features.

[0056] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0057] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fine-cutting tooth broach, comprising a broach body (1), calibration teeth (2), rough-cutting teeth (3) and fine-cutting teeth (4), characterized in that: The front and rear ends of the surface of the broach body (1) are respectively provided with fixing screw holes (5), and the bottom of the broach body (1) is provided with evenly distributed positioning screw holes (6). The upper surface of the broach body (1) is provided with calibration teeth (2), rough cutting teeth (3) and fine cutting teeth (4) from left to right. The calibration teeth (2) include a plurality of teeth with equal tooth heights, the tooth height of the rough cutting teeth (3) gradually increases, and the tooth heights of the fine cutting teeth (4) are equal to each other. The front and rear ends of the broach body (1) are both provided with guide parts (7).

2. A fine-cutting tooth broach according to claim 1, characterized in that: The tooth spacing between the finishing teeth (4) is 6.986 mm, a chip groove (8) is provided between the finishing teeth (4), the radius of the bottom of the chip groove (8) is 1.6 mm, and the angle between the inner wall of the chip groove (8) and the front tooth is 50°.

3. A fine-cutting tooth broach according to claim 1, characterized in that: The surface of the calibration tooth (2) is provided with chip dividing grooves (9), and the chip dividing grooves (9) are staggeredly distributed in the form of two in front and one in the back.

4. A fine-cutting tooth broach according to claim 1, characterized in that: Guide slopes (10) are respectively provided at the edges of both sides of the guide portion (7), and the guide slopes (10) are inclined at 5°.

5. A fine-cutting tooth broach according to claims 1-4, characterized in that: The processing technology of the fine cutting tooth broach comprises the following steps: (1) Blanking: Use a sawing machine to cut high-speed steel bars for processing the broach body (1), and retain a certain processing allowance to facilitate subsequent processing of the blank; (2) Lathe processing: Use a lathe to process the ends and surfaces of the blanks, remove the black skin on the surface of the blanks and the burrs from sawing at the ends, improve the size accuracy of the blanks, and use a drill to open fixing holes at both ends to facilitate subsequent processing to fix the burrs; (3) Milling: The blank is mounted on a precision chuck and processed using a CNC milling machine to remove excess material from the surface of the blank to obtain a spare part that conforms to the shape of the broach body; and positioning holes are evenly distributed at the bottom of the blank, with a spacing of (130) mm. (4) Tapping: Use a tapping machine to tap the fixing holes and positioning holes for positioning during tooth cutting, improve the convenience of fixed installation, and ensure the accuracy of tooth processing on the surface of the broach body; (5) Wire cutting rough processing: Use a CNC electric spark wire cutting machine to cut the surface of the spare part, wire cutting rough processing of the calibration teeth (2), rough cutting teeth (3) and fine cutting teeth (4) on the surface of the broach body, and use the positioning hole as the reference when wire cutting the tooth shape; (6) Heat treatment: The broach body (1) after the tooth profile processing is placed in a vacuum furnace for vacuum quenching and vacuum tempering treatment, so as to obtain good comprehensive mechanical properties and small workpiece deformation. After the heat treatment, the spacing between the positioning holes is (129). (7) mm, and the hardness after quenching is (64)-(65) HRC; (7) Cold treatment: placing the broach body (1) after the heat treatment in a liquid nitrogen cooling box for low-temperature aging treatment to shape the internal structure of the material and thus improve the stability of the cutter head size; (8) Wire cutting finishing: using a precision CNC wire-cutting machine tool, and utilizing the four-axis four-linkage CNC wire-cutting function of the precision CNC wire-cutting machine tool, the precision cutting teeth (4) and chip grooves (8) with inclination angles are precisely cut; wherein the precision cutting of the precision cutting teeth (4) and chip grooves (8) is completed in one clamping to improve the accuracy of the broach body processing and avoid the clearance generated by repeated clamping; (9) Tooth profile fine grinding: Use a precision cylindrical grinder to install the broach body on a positioning fixture, and use the grinder to perform precision grinding on the surface of the teeth to ensure the shape and position tolerances of each tooth in the same group.

6. The processing technology of a fine-cutting tooth broach according to claim 5, characterized in that: The fixing hole and the positioning hole have the same size, the diameter of the fixing hole is 6 mm, and the depth of the fixing hole is 12-15 mm.

7. The processing technology of a fine-cutting tooth broach according to claim 5, characterized in that: The quenching temperature during the vacuum quenching treatment is 1180° C., the temperature of the vacuum tempering is 175-350° C., and the tempering time is about 2 hours.

8. The processing technology of a fine-cutting tooth broach according to claim 5, characterized in that: The precision cylindrical grinder is divided into three grinding process steps during grinding, namely, plane rough grinding, plane semi-finishing grinding and plane fine grinding, and cooling treatment is performed between the plane rough grinding, plane semi-finishing grinding and plane fine grinding processes.

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