Static pressure tool rest of gear shaping machine and operation method

Abstract

The invention provides a gear shaper static pressure knife rest and an operation method, the gear shaper static pressure knife rest comprises an eccentric disc, a swing rod is hinged to the eccentric disc, and the other end of the swing rod is hinged to the top end of a knife shaft through a ball pull rod and a ball head; the cutter shaft penetrates through the cutter rest body; a cutter is mounted at the lower end of the cutter shaft; a worm gear and a worm are installed at the upper end of the tool rest body, and the worm gear is pressed through a large flange plate to be axially fixed. The cutter shaft penetrates through the worm gear and an inner hole of the cutter shaft sleeve at the same time. Due to the fact that the outer circle profile face of the four-tooth tooth-shaped tooth crest of the formed hydrostatic guide rail is wide, enough space can be provided for designing a radial four-cavity centripetal hydrostatic bearing, and therefore the upper end of a cutter shaft not only has centripetal clamping static pressure formed by static pressure cavities of involute tooth faces of the hydrostatic spline guide rail but also has static pressure clamping force of the tooth crest. The rigidity of the upper end of the cutter shaft is enhanced through superposition of the two clamping forces.

Description

Technical Field

[0001] The invention relates to the technical field of gear shaping machine tool holders, and in particular to a gear shaping machine static pressure tool holder and an operating method thereof. Background Art

[0002] The gear shaping machine is a common equipment for processing cylindrical gears, usually used for processing deep hole internal gears. It mainly cuts by rotating the worktable and the cutter shaft according to the rolling ratio, while the cutter shaft moves up and down. The tool holder wraps the cutter shaft, mainly supporting the rotation of the cutter shaft and the up and down movement of the cutter shaft. In order to meet the high precision and high efficiency requirements of gear shaping, the movement of the cutter shaft in the tool holder needs to have the characteristics of high rigidity and low wear. At present, this problem is mainly solved by static pressure tool holder technology at home and abroad.

[0003] The existing tool holders using hydrostatic technology are generally designed with a four-cavity centripetal hydrostatic bearing at the lower end of the tool holder. The four oil chambers are evenly distributed around the tool shaft sleeve. The hydraulic oil of constant pressure is passed to the four oil chambers through the throttle to form a hydraulic centripetal thrust to make the tool shaft have a higher radial rigidity. The upper end of the tool holder is designed as a hydrostatic guide rail similar to the hydrostatic spline structure. Four involute tooth profiles are evenly distributed around the guide rail. Hydrostatic oil chambers are designed on both sides of the tooth profile. The hydraulic oil of constant pressure is also passed to each oil chamber through the throttle. The generated hydrostatic thrust is inward along the normal direction of the tooth surface. The combined force of the hydrostatic thrust on both sides of the tooth profile is the centripetal thrust and the clamping force that suppresses the rotational motion. The characteristics of the static pressure resultant force are as follows: the static pressure resultant force on both sides of the four involute tooth profiles can be decomposed into two directions of force. One is the centripetal force pointing to the center of the knife shaft. The centripetal force formed by the four tooth profiles is evenly distributed around the knife shaft and all points to the axis. The four centripetal thrusts make the upper end of the knife shaft have radial rigidity to maintain the center position; the other part of the force can be understood as a pair of thrusts in opposite directions along the tangent direction of the pitch circle at the pitch circle of the center surface of the tooth profile. The two thrusts are of the same magnitude and play the role of clamping the tooth profile to prevent the rotation of the knife shaft. A static pressure bearing is installed at the lower end of the knife shaft, and a static pressure guide rail is installed at the upper end. A worm gear is installed on the outside of the static pressure guide rail, so that the knife shaft can move up and down and rotate with the worm gear at the same time.

[0004] Since the main motion of the gear shaping machine is to convert the rotational motion of the main motor into the up and down motion of the tool holder and the tool shaft through the crank slider structure. The longer the up and down motion stroke of the tool shaft, the greater the eccentricity of the swing arm at the installation position on the eccentric disk, the greater the maximum angle formed by the swing arm and the tool shaft when swinging, and the greater the radial force component on the upper end of the tool shaft. In order to keep the tool shaft vertical when subjected to radial thrust, it is necessary to increase the static rigidity of the static guide rail at the upper end of the tool shaft. Therefore, in actual use, especially when processing gears with super large tooth width, the vertical accuracy of the tool shaft is difficult to guarantee, and the tooth direction accuracy of the processed gear is not good. Summary of the invention

[0005] The object of the present invention is to overcome the above-mentioned shortcomings and provide a hydrostatic tool holder for a gear shaping machine and an operating method thereof. By forming a hydrostatic guide rail with a four-tooth tooth profile with a wider outer circumferential profile surface of the tooth top, there is enough space to design a radial four-cavity centripetal hydrostatic bearing. In this way, the upper end of the tool shaft not only has the centripetal clamping static pressure formed by the hydrostatic cavity of the involute tooth surface of the hydrostatic spline guide rail, but also has the hydrostatic clamping force of the tooth top. The superposition of the two clamping forces enhances the rigidity of the upper end of the tool shaft.

[0006] In order to realize the above-mentioned technical features, the object of the present invention is realized as follows: a static pressure tool holder of a gear shaping machine comprises an eccentric disk, a rocker arm is hinged on the eccentric disk, the other end of the rocker arm is hingedly connected to the top end of the tool shaft through a ball head via a ball tie rod; the tool shaft passes through a tool holder body, and a tool is installed at the lower end of the tool shaft; a worm gear and a worm are installed at the upper end of the tool holder body, and the worm gear is pressed by a large flange to fix it axially; a tool shaft sleeve and a sealing ring are installed at the lower end of the tool holder body, and the tool shaft passes through the inner holes of the worm gear and the tool shaft sleeve at the same time.

[0007] The eccentric disk is connected to a driving motor and is driven to rotate by the motor.

[0008] The top end of the swing rod is hinged on the outer wall of the eccentric disk through rotation.

[0009] The bottom end of the swing rod is connected to the ball pull rod through a thread, and the ball head of the ball pull rod is hingedly connected to the top end of the knife shaft.

[0010] The inner hole of the knife shaft sleeve is evenly distributed with 4 static pressure oil chambers, and the pressure oil is passed to form a centripetal static pressure bearing. The knife shaft sleeve wraps the knife shaft in an annular shape, and the gap between the two is 0.02-0.04mm; the lower end of the knife shaft is sealed by a sealing ring.

[0011] The inner hole of the worm wheel cooperates with the cutter shaft to form a toothed guide rail structure with an involute spline. A tooth side static pressure oil chamber is distributed on the tooth side of each toothed guide rail structure, and a tooth top static pressure oil chamber is distributed on the tooth top of each toothed guide rail structure, and a static pressure guide rail is formed by pressure oil.

[0012] The toothed guide rail structure adopts a positive displacement involute cylindrical gear tooth profile with twelve teeth, two adjacent teeth are merged, and redundant teeth are removed at the tooth groove, thereby forming four groups of toothed guide rail structures.

[0013] The outer arc surface of the hydrostatic guide rail is used to form a 4-cavity centripetal hydrostatic bearing to improve the overall hydrostatic stiffness of the cutter shaft.

[0014] The tooth top profile of the toothed guide rail structure is a standard outer arc surface, which is then processed with high precision using an external cylindrical grinder to ensure that the circumference of the outer cylindrical surface of the guide rail is within 0.005mm and the oil film clearance is controlled at 0.02~0.04mm.

[0015] A method for operating a static pressure tool holder of a gear shaping machine comprises the following steps: During operation, the eccentric disk drives the swing rod, the swing rod drives the cutter shaft, and the cutter shaft drives the cutter to achieve reciprocating motion; In the process of matching the cutter shaft and the inner hole of the worm wheel, based on the tooth profile shape of the hydrostatic guide rail, its hydrostatic oil chambers are not only distributed on both sides of the tooth profile, but also on the large tooth top surface. The inside of the worm wheel is a hydrostatic guide sleeve, and oil circuits are distributed around it to provide hydraulic oil with constant pressure to each hydrostatic oil chamber, thereby forming a radial four-cavity centripetal hydrostatic bearing. In this way, the upper end of the cutter shaft not only has the centripetal clamping static pressure formed by the hydrostatic chamber of the involute tooth surface of the hydrostatic guide rail, but also has the hydrostatic clamping force of the tooth top. The superposition of the two clamping forces enhances the rigidity of the upper end of the cutter shaft.

[0016] The present invention has the following beneficial effects: 1. The hydrostatic guide rail of the present invention has a four-tooth involute tooth profile, which is a twelve-tooth positive displacement involute cylindrical gear tooth profile, formed by merging two adjacent teeth, and removing redundant teeth at the tooth groove. Its characteristic is that the outer circumferential profile of the tooth top of the four-tooth tooth profile formed is relatively wide, and there is enough space to design a radial four-cavity centripetal hydrostatic bearing. In this way, the upper end of the cutter shaft not only has the centripetal clamping static pressure formed by the hydrostatic cavity of the involute tooth surface of the hydrostatic spline guide rail, but also has the hydrostatic clamping force of the tooth top. The superposition of the two clamping forces enhances the rigidity of the upper end of the cutter shaft.

[0017] 2. A tool shaft sleeve is fixed to the lower end of the tool shaft hole of the tool holder body of the present invention, and four static pressure oil chambers are evenly distributed on the inner side of the tool shaft sleeve. The tool shaft sleeve wraps the tool shaft in a ring shape, and the gap between the two is only 0.02~0.04mm. A worm gear is installed on the upper end of the tool holder body. The center of the worm gear is coaxial with the tool shaft, and the upper and lower end surfaces are fixed by the tool holder body and the large flange. The tool shaft passes through the center of the worm gear to form a four-tooth static pressure guide rail structure.

[0018] 3. The tooth profile of the traditional hydrostatic spline guide is an eight-tooth positive displacement involute cylindrical gear tooth profile, and the redundant teeth in the tooth groove are removed. The tooth profile of the present invention is a twelve-tooth positive displacement involute cylindrical gear tooth profile, which is formed by merging two adjacent teeth, and the redundant teeth in the tooth groove are removed. Its advantage is that the tooth top profile of the merged teeth is wider, and there is enough space to design a four-cavity radial hydrostatic bearing. The bottom profile of the tooth groove of the traditional hydrostatic spline guide is also wider, but since it is impossible to fine-machine and grind to control the accuracy and clearance, it is impossible to design a hydrostatic bearing. The tooth top profile of the guide rail of the present invention is a standard outer circular arc surface, which can be processed with high precision using an external cylindrical grinder to ensure that the circumference of the outer cylindrical surface of the guide rail is within 0.005mm, and the oil film gap is controlled at 0.02~0.04mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] Figure 1(a), (b), and (c) are overall structural diagrams of the present invention.

[0021] Figure 2 for Figure 1 The AA cross-section diagram reflects the tooth profile shape of the hydrostatic guide rail in the traditional hydrostatic tool holder.

[0022] Figure 3 (a) and (b) are comparisons between the cross-sections of a conventional hydrostatic spline guide and the hydrostatic spline guide of the present invention.

[0023] Figure 4 Figure 1 The AA cross-sectional view reflects the tooth profile shape of the hydrostatic guide rail in the hydrostatic tool holder of the present invention.

[0024] In the figure: eccentric disc 1, rocker arm 2, ball pull rod 3, tool shaft 4, large flange 5, worm gear 6, worm 7, tool holder body 8, tool shaft sleeve 9, sealing ring 10, tool 11, first oil return chamber 12, first static pressure oil chamber 13, first removed tooth portion 14, retained tooth groove portion 15, second removed tooth portion 16, tooth top static pressure oil chamber 17, tooth top return oil chamber 18, tooth side static pressure oil chamber 19, tooth heel return oil chamber 20, tooth guide rail structure 21. DETAILED DESCRIPTION

[0025] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0026] Embodiment 1: See also Figure 1 A static pressure tool holder for a gear shaping machine comprises an eccentric disk 1, a rocker arm 2 is hinged on the eccentric disk 1, the other end of the rocker arm 2 is hingedly connected to the top end of a tool shaft 4 through a ball head through a ball tie rod 3; the tool shaft 4 passes through a tool holder body 8, and a tool 11 is installed at the lower end of the tool shaft 4; a worm wheel 6 and a worm 7 are installed at the upper end of the tool holder body 8, and the worm wheel 6 is pressed by a large flange 5 to fix it axially; a tool shaft sleeve 9 and a sealing ring 10 are installed at the lower end of the tool holder body 8, and the tool shaft 4 passes through the inner holes of the worm wheel 6 and the tool shaft sleeve 9 at the same time.

[0027] Furthermore, the eccentric disk 1 is connected to a driving motor and is driven to rotate by the motor.

[0028] Furthermore, the top end of the swing rod 2 is hinged to the outer wall of the eccentric disk 1 by rotation.

[0029] Furthermore, the bottom end of the swing rod 2 is connected to the ball pull rod 3 through a thread, and the ball head of the ball pull rod 3 is hingedly connected to the top end of the knife shaft 4.

[0030] Furthermore, the inner hole of the knife shaft sleeve 9 is evenly distributed with four static pressure oil chambers, through which the pressure oil forms a centripetal static pressure bearing. The knife shaft sleeve 9 wraps the knife shaft 4 in a ring shape, and the gap between the two is 0.02~0.04mm; the lower end of the knife shaft 4 is sealed by a sealing ring 10.

[0031] Furthermore, the inner hole of the worm wheel 6 cooperates with the cutter shaft 4 to form an involute spline toothed guide structure 21, each toothed guide structure 21 has a tooth side static oil chamber 19 distributed on the tooth side, each toothed guide structure 21 has a tooth top static oil chamber 17 distributed on the tooth top, and a static pressure guide is formed by pressurized oil.

[0032] Furthermore, the toothed guide rail structure 21 adopts a positive displacement involute cylindrical gear tooth profile with twelve teeth, two adjacent teeth are merged, and redundant teeth are removed at the tooth groove, thereby forming four groups of toothed guide rail structures 21.

[0033] Furthermore, a 4-cavity radial hydrostatic bearing is formed by utilizing the outer arc surface of the hydrostatic guide rail to improve the overall hydrostatic stiffness of the cutter shaft.

[0034] Furthermore, the tooth top profile of the toothed guide rail structure 21 is a standard outer arc surface, and then a cylindrical grinder is used for high-precision machining to ensure that the circumference of the outer cylindrical surface of the guide rail is within 0.005 mm and the oil film gap is controlled within 0.02-0.04 mm.

[0035] like Figure 2 As shown, Figure 1 The AA cross-sectional view in the middle reflects the tooth profile shape of the hydrostatic guide rail in the traditional hydrostatic tool holder. The first hydrostatic oil chamber 13 is only distributed on both sides of the tooth profile, and the first return oil chamber 12 is distributed at the tooth top and tooth heel. The inside of the worm gear 6 is a hydrostatic guide sleeve, and oil circuits are distributed around it to provide each first hydrostatic oil chamber 13 with hydraulic oil of constant pressure.

[0036] like Figure 3 The figure shows the difference between the cross section of the conventional hydrostatic spline guide and the cross section of the hydrostatic spline guide of the present invention. Figure 3 (a) is a traditional structure, which is an eight-tooth positive displacement involute tooth shape. The first tooth portion 14 removed from the interval is enlarged to form a large tooth groove static pressure spline guide; right Figure 3 (b) is the structure of the present invention, which is a twelve-tooth positive displacement involute tooth shape, removing the four second removed tooth portions 16 at intervals, enlarging the tooth groove, including the retained tooth groove portion 15, and merging adjacent tooth shapes to form a large tooth top static pressure spline guide.

[0037] like Figure 4 As shown, Figure 1The AA cross-sectional view reflects the tooth profile shape of the hydrostatic guide rail in the hydrostatic tool holder of the present invention. Its hydrostatic oil chambers are not only distributed on both sides of the tooth profile to form tooth side hydrostatic oil chambers 19, but also on the top surface of the large tooth to form a tooth top hydrostatic oil chamber 17. The inside of the worm gear 6 is a hydrostatic guide sleeve, and oil circuits are distributed around it to provide hydraulic oil of constant pressure to each hydrostatic oil chamber.

[0038] The working principle of the present invention is as follows: the four-tooth involute tooth profile of the hydrostatic spline guide is a twelve-tooth positive displacement involute cylindrical gear tooth profile, formed by merging two adjacent teeth, and removing redundant teeth at the tooth groove. Its characteristic is that the outer circumferential profile of the tooth top of the formed four-tooth tooth profile is relatively wide, and there is enough space to design a radial four-cavity centripetal hydrostatic bearing. In this way, the upper end of the cutter shaft not only has the centripetal clamping static pressure formed by the hydrostatic cavity of the involute tooth surface of the hydrostatic spline guide, but also has the hydrostatic clamping force of the tooth top. The superposition of the two clamping forces enhances the rigidity of the upper end of the cutter shaft.

[0039] A method for operating a static pressure tool holder of a gear shaping machine comprises the following steps: During operation, the eccentric disk 1 drives the swing rod 2, the swing rod 2 drives the cutter shaft 4, and the cutter shaft 4 drives the cutter 11 to achieve reciprocating motion; During the matching process between the cutter shaft 4 and the inner hole of the worm wheel 6, based on the tooth profile shape of the hydrostatic guide rail, its hydrostatic oil chambers are not only distributed on both sides of the tooth profile, but also on the large tooth top surface. The inside of the worm wheel 6 is a hydrostatic guide sleeve, and oil circuits are distributed around it to provide hydraulic oil of constant pressure to each hydrostatic oil chamber, thereby forming a radial four-cavity centripetal hydrostatic bearing. In this way, the upper end of the cutter shaft not only has the centripetal clamping static pressure formed by the hydrostatic chamber of the involute tooth surface of the hydrostatic guide rail, but also has the hydrostatic clamping force of the tooth top. The superposition of the two clamping forces enhances the rigidity of the upper end of the cutter shaft.

Claims

1. A static pressure tool holder for a gear shaping machine, characterized in that: The invention comprises an eccentric disk (1), a swing rod (2) is hingedly connected to the eccentric disk (1), and the other end of the swing rod (2) is hingedly connected to the top end of a tool shaft (4) through a ball tie rod (3) through a ball head; the tool shaft (4) passes through a tool holder body (8), and a tool (11) is installed at the lower end of the tool shaft (4); a worm wheel (6) and a worm (7) are installed at the upper end of the tool holder body (8), and the worm wheel (6) is pressed by a large flange (5) to be axially fixed; a tool shaft sleeve (9) and a sealing ring (10) are installed at the lower end of the tool holder body (8), and the tool shaft (4) passes through the inner holes of the worm wheel (6) and the tool shaft sleeve (9) at the same time.

2. The hydrostatic tool holder for a gear shaping machine according to claim 1, characterized in that: The eccentric disk (1) is connected to a driving motor and is driven to rotate by the motor.

3. The static pressure tool holder of a gear shaping machine according to claim 1, characterized in that: The top end of the swing rod (2) is hinged on the outer wall of the eccentric disc (1) by rotation.

4. The static pressure tool holder of a gear shaping machine according to claim 1, characterized in that: The bottom end of the swing rod (2) is connected to the ball pull rod (3) via a thread, and the ball head of the ball pull rod (3) is hingedly connected to the top end of the knife shaft (4).

5. The static pressure tool holder of a gear shaping machine according to claim 1, characterized in that: The inner hole of the knife shaft sleeve (9) is evenly distributed with four static pressure oil chambers, through which pressure oil is passed to form a centripetal static pressure bearing. The knife shaft sleeve (9) wraps the knife shaft (4) in an annular shape, and a gap between the two is 0.02-0.04 mm; the lower end of the knife shaft (4) is sealed by a sealing ring (10).

6. The static pressure tool holder of a gear shaping machine according to claim 5, characterized in that: The inner hole of the worm wheel (6) cooperates with the cutter shaft (4) to form an involute spline toothed guide rail structure (21), a tooth side static pressure oil chamber (19) is distributed on the tooth side of each toothed guide rail structure (21), a tooth top static pressure oil chamber (17) is distributed on the tooth top of each toothed guide rail structure (21), and a static pressure guide rail is formed by pressure oil.

7. The static pressure tool holder of a gear shaping machine according to claim 6, characterized in that: The toothed guide rail structure (21) adopts a positive displacement involute cylindrical gear tooth profile with twelve teeth, two adjacent teeth are merged, and redundant teeth are removed at the tooth groove, thereby forming four groups of toothed guide rail structures (21).

8. The static pressure tool holder of a gear shaping machine according to claim 7, characterized in that: The outer arc surface of the hydrostatic guide rail is used to form a 4-cavity centripetal hydrostatic bearing to improve the overall hydrostatic stiffness of the cutter shaft.

9. The static pressure tool holder of a gear shaping machine according to claim 7, characterized in that: The tooth top profile surface of the toothed guide rail structure (21) is a standard outer arc surface, and is then processed with high precision using an outer cylindrical grinder to ensure that the circumference of the outer cylindrical surface of the guide rail is within 0.005 mm and the oil film gap is controlled within 0.02-0.04 mm.

10. The method for operating a static pressure tool holder of a gear shaping machine according to any one of claims 6 to 9, characterized in that: The following steps are involved: During operation, the eccentric disk (1) drives the swing rod (2), the swing rod (2) drives the knife shaft (4), and the knife shaft (4) drives the knife (11) to achieve reciprocating motion; During the matching process between the cutter shaft (4) and the inner hole of the worm wheel (6), based on the tooth profile shape of the hydrostatic guide rail, its hydrostatic oil chambers are not only distributed on both sides of the tooth profile, but also on the large tooth top surface. The interior of the worm wheel (6) is a hydrostatic guide sleeve, and oil circuits are distributed around it to provide hydraulic oil of constant pressure to each hydrostatic oil chamber, thereby forming a radial four-cavity centripetal hydrostatic bearing. In this way, the upper end of the cutter shaft not only has the centripetal clamping static pressure formed by the hydrostatic chamber of the involute tooth surface of the hydrostatic guide rail, but also has the hydrostatic clamping force of the tooth top. The superposition of the two clamping forces enhances the rigidity of the upper end of the cutter shaft.

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