A high-precision flexible gear machining liquid-expansion clamp

Abstract

The utility model provides a kind of high-precision liquid expansion clamp of flexible gear machine processing, it is related to harmonic speed reducer processing field, including fixture body and sealing cover;Oil circuit part, inside is full of hydraulic oil, oil circuit part includes flow channel a and transition oil circuit, flow channel a is located in the sealing gap formed by fixture body and sealing cover, flow channel a and transition oil circuit are communicated, the deformation ability of one side wall of flow channel a is higher than another side;Starting part is set at the port of transition oil circuit, can be moved along the extension direction of transition oil circuit, to extrude the hydraulic oil in transition oil circuit to move to flow channel a, the present application adopts hydraulic oil pressure accurate positioning and can be respectively clamped to flexible gear from inside and outside two sides, simultaneously, user can select to press by hand, can also select to adopt machine tool automatic pressure application. Through machine tool automatic pressure application, the labor intensity of operator can be reduced, and the high positioning accuracy and stable clamping capacity of workpiece are also guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of harmonic reducer processing, and in particular to a high-precision hydraulic expansion clamp for flexural machining. Background Technology

[0002] Due to their thin walls, susceptibility to deformation, and high machining precision, the manufacturing process of harmonic reducer flexsplines involves multiple steps (such as turning and gear machining), requiring high-precision fixtures to ensure reliable positioning and prevent deformation. Existing fixture solutions have limitations: rigid mandrels require multiple tooling sets for different bore diameters, resulting in low efficiency; elastic mandrels suffer from poor fit due to uneven axial force, easily leading to bending deformation. While hydraulic expansion fixtures utilize hydraulic expansion for clamping, existing patented structures lack sufficient sealing, posing risks of hydraulic oil leakage and unstable clamping force; electromagnetic fixtures suffer from poor clamping reliability due to low output force. Current technical solutions still have deficiencies in sealing performance, deformation control, and clamping stability, hindering the large-scale, efficient production of flexsplines. Utility Model Content

[0003] In order to overcome the above-mentioned defects of the prior art, the embodiments of this utility model provide a high-precision hydraulic expansion fixture for flexural machining. The technical problem to be solved by this utility model is: how to design the fixture to simultaneously meet the requirements of high sealing performance, uniform expansion and stress control.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a high-precision hydraulic expansion fixture for flexural machining, comprising a fixture part, including a fixture body and a sealing cover, the fixture body being fixedly connected to a lathe flange, and the sealing cover being sleeved along the axial direction of the fixture body; an oil passage part, filled with hydraulic oil, including a flow channel a and a transition oil passage, the flow channel a being located in the sealing gap formed by the fixture body and the sealing cover, the flow channel a being connected to the transition oil passage, and the deformation capacity of one sidewall of the flow channel a being higher than that of the other side; and a starting part, located at the port of the transition oil passage, which can move along the extension direction of the transition oil passage to squeeze the hydraulic oil in the transition oil passage toward the flow channel a.

[0005] In a preferred embodiment, the wall thickness of the clamp body located on one side of the flow channel a is less than the wall thickness of the sealing cover on the other side. Here, the deformation capability of the clamp body is higher than that of the sealing cover, and the clamp body is used to wrap around and clamp the outer wall of the flexible wheel.

[0006] In a preferred embodiment, the wall thickness of the clamp body located on one side of the flow channel a is greater than the wall thickness of the sealing cover on the other side. The deformation capability of the clamp body is weaker than that of the sealing cover, which is used to externally support the inner wall of the flexible wheel.

[0007] In a preferred embodiment, the oil circuit further includes interconnected flow channels b, c, d, and e. Flow channel a is formed between an annular groove on the outer arc surface of one end of the clamp body and the inner wall of the sealing cap. Flow channel c is provided inside the clamp body. An annular slit flow channel b is provided at the end face step where the clamp body mates with the sealing cap. Flow channels a, b, and c are interconnected. Flow channel d is connected to the oil inlet on the clamp body, and flow channel e is connected to the piston chamber on the clamp body. Both the oil inlet and the piston chamber have a starting part at their ports.

[0008] In a preferred embodiment, the starting part includes a piston I, which is detachably connected to the clamp body. A plurality of sealing rings are fitted on the piston I inserted into the piston cavity, and the piston I is connected to the telescopic end of the telescopic component.

[0009] In a preferred embodiment, flow channel e and flow channel d are coaxially arranged, and their axes are perpendicular to the axis of the piston chamber.

[0010] In a preferred embodiment, the starting part includes piston II, which is detachably connected to the clamp body. Piston II is attached to the end face of the oil inlet. The clamp body has a threaded limiting hole, which is coaxial with the oil inlet. A threaded plug is threadedly connected in the threaded limiting groove. The threaded plug is used to press piston II onto the end face of the oil inlet.

[0011] In a preferred embodiment, the piston II has a flow channel f communicating with the flow channel d. A sealing ball for blocking the flow channel f is placed between the flow channel f and the threaded plug. The threaded plug is used to press the sealing ball at the port of the flow channel f.

[0012] In a preferred embodiment, the gap between the clamp body and the sealing cap is filled with sealant.

[0013] In a preferred embodiment, the end of the fixture body furthest from the flow channel a is a frustum of a cone, the taper of which is Morse taper 2, and the error between the actual rotation center of the frustum and the theoretical rotation center is less than 3. The coaxiality error of the inner hole of the fixture body at flow channel a relative to the theoretical center of rotation is less than or equal to 3. .

[0014] The technical effects and advantages of this utility model are as follows:

[0015] This application utilizes hydraulic pressure for precise positioning and clamps the flexible wheels from both the inner and outer sides. Users can choose to apply pressure manually or automatically via the machine tool. Automatic machine tool pressure reduces operator workload while ensuring high workpiece positioning accuracy and stable clamping capability. This extends the lifespan of the fixture body and achieves near-maintenance-free operation, thereby improving production efficiency. Attached Figure Description

[0016] The disclosure of this utility model is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:

[0017] Figure 1 This is a structural diagram of one clamping form of the liquid expansion clamp in this utility model.

[0018] Figure 2 This is a structural diagram of another clamping form of the liquid expansion clamp in this utility model.

[0019] Figure 3 This is a structural diagram of piston I in this utility model.

[0020] Figure 4 This is a structural diagram of the threaded plug in this utility model.

[0021] Figure 5 This is a structural diagram of the flexible wheel in this utility model.

[0022] Figure 6 This is a structural diagram of the sealing cap in this utility model.

[0023] Figure 7 This is a structural diagram of the clamp body in this utility model.

[0024] Figure 8 This is an assembly drawing of piston II and sealing ball in this utility model.

[0025] The attached figures are labeled as follows: 1. Fixture body; 2. Sealing cover; 3. Threaded plug; 4. Piston I; 5. Flow channel; 6. Sealing ball; 7. Flexible wheel; 8. Piston II. Detailed Implementation

[0026] It is readily understood that, based on the technical solution of this utility model, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of this utility model. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative descriptions of the technical solution of this utility model and should not be considered as the entirety of this utility model or as limitations or restrictions on the technical solution of this utility model.

[0027] Example

[0028] like Figure 1 - Figure 7 The hydraulic expansion clamp mainly consists of the clamping part, the oil circuit part, and the starting part.

[0029] The fixture part includes a fixture body 1 and a sealing cover 2. The outer circumference of the fixture body 1 is provided with evenly distributed cylindrical countersunk holes. After passing through the cylindrical countersunk holes, the fixture body 1 and the lathe flange are fixed.

[0030] The right end of the fixture body 1 is a conical boss designed with Morse taper No. 2. The conical surface of the conical boss serves as the positioning reference surface of the fixture body 1, and the runout of the reference surface relative to the theoretical center of rotation does not exceed 3. By connecting the tapered boss to the lathe flange, high positioning accuracy is ensured, thereby eliminating concentricity errors caused by radial dimension manufacturing errors.

[0031] A piston I4 is embedded in the right end face of the fixture body 1. One end of the piston I4 passes through a piston cavity formed on the end face of the fixture body 1. Several sealing rings are fitted on the piston I4 inside the piston cavity to improve the sealing performance of the piston I4 and the piston cavity for hydraulic oil, ensuring that the hydraulic oil does not leak when the piston I4 moves in the piston cavity. A flange is fixed to the piston I4. The flange has six rectangular countersunk holes evenly formed along the circumference. Threaded fasteners pass through the rectangular countersunk holes and connect the piston I4 to the fixture body 1.

[0032] The clamp body 1 has multiple screw holes near the middle of the outer circumference of the left end. The sealing cover 2 is installed along the axial direction of the clamp body 1 through multiple screws. The clamp body 1 and the sealing cover 2 form an oil passage for hydraulic oil to move. The oil passage is filled with hydraulic oil.

[0033] The oil passage includes flow channels 5a, 5b, 5c, 5d, and 5e. Flow channel 5a is formed between the annular groove on the outer arc surface of the left end of the fixture body 1 and the inner wall of the sealing cap 2.

[0034] like Figure 1 The hydraulic oil pressure acts on the flow channel 5a, causing the thin wall of the clamp body 1 at the annular groove to undergo radial deformation, thereby allowing the clamp body 1 to wrap and clamp the flexible wheel 7 from the outside.

[0035] like Figure 2 When the wall thickness of the clamp body 1 at the flow channel 5a is greater than the wall thickness of the sealing cover 2, the hydraulic oil entering the flow channel 5a squeezes the sealing cover 2, causing it to undergo radial deformation, and opens and clamps the flexible wheel 7 from the inside.

[0036] The two clamping methods described above can clamp the inner and outer walls of the flexible wheel 7 respectively.

[0037] The fixture body 1 has a flow channel 5c inside. The end face step where the fixture body 1 mates with the sealing cover 2 has an annular slit flow channel 5b. Flow channels 5a, 5b and 5c are connected. The fixture body 1 also has flow channels 5d and 5e inside. Flow channels 5d and 5e are connected to flow channel 5c.

[0038] The piston chamber and the flow channel 5e are connected.

[0039] The oil inlet and flow channel 5d on one side of the fixture body 1 are connected.

[0040] Preferably, flow channels 5d and 5e are coaxially arranged, and their axes are perpendicular to the axis of the piston chamber.

[0041] The starting unit is piston II8 or piston I4. This hydraulic expansion clamp can be manually pressurized by piston II8 or pressurized by machine tool by piston I4.

[0042] In terms of manual pressurization, the oil inlet is connected to a piston II8 via an internal thread. By manually turning the piston II8, the piston II8 compresses the hydraulic oil and passes it through flow channels 5d, 5c, and 5b in sequence, finally reaching flow channel 5a. This drives the thin wall of flow channel 5a to deform and clamp the outer side of the flexible wheel 7.

[0043] In terms of pressurizing the machine tool, the piston I4 is driven to move within the fixture body 1 by the pneumatic / hydraulic device installed on the machine tool. The piston I4 squeezes the hydraulic oil to flow through the flow channels 5e, 5c and 5b respectively and finally reach the flow channel 5a, so as to drive the thin wall of the flow channel 5a to deform and clamp the outer side of the flexible wheel 7.

[0044] The pneumatic / hydraulic device can be a pneumatic cylinder or a hydraulic cylinder, etc., whose telescopic end is connected to the piston I4 to drive the piston I4 to move linearly.

[0045] It should be noted that only one of the manual pressurization and machine tool pressurization methods needs to be used. In manual pressurization mode, piston I4 is in the off state, secured by six screws to six screw holes on the right end face of the fixture body 1, ensuring that piston I4 will not move accidentally. In machine tool pressurization mode, piston I4 is in the active state. At this time, the screws in this location need to be removed to allow piston I4 to move axially and compress the hydraulic oil to generate the required oil pressure. Piston II8, due to the self-locking capability of its externally mounted threaded plug 3, can prevent accidental movement of itself while piston I4 is moving.

[0046] Specifically, piston II8 is placed on the oil inlet end face of the clamp body 1. Several sealing rings are fitted around the periphery of piston II8 to improve the sealing between piston II8 and the oil inlet. Piston II8 has a flow channel 5f that communicates with flow channel 5d. At the end of flow channel 5f, a sealing ball 6 is placed to block flow channel 5f. A threaded plug 3 is threadedly connected to the inner wall of a threaded limiting hole. The threaded limiting hole and the oil inlet are coaxially arranged to press the sealing ball 6 against the port of flow channel 5f, preventing hydraulic oil from overflowing from the port of flow channel 5f. The advantage of this design is that air in the entire oil circuit can be discharged using the easily removable threaded plug 3 and flow channel 5f, thus keeping the hydraulic oil stable during movement.

[0047] Specifically, after filling the oil passage with hydraulic oil, the piston II8 is inserted into the oil inlet while the air in the oil passage is expelled. Then, the sealing ball 6 is placed into the conical groove on the outer end face of the piston II81, and finally the threaded plug 3 is screwed in.

[0048] Calculations show that the piston II8, when screwed in, generates an axial displacement of 2.1 mm, which can cause the hydraulic oil to produce a pressure of 16 MPa. The specific calculation method is as follows:

[0049] ΔP=ΔV / V / K

[0050] ΔV=A*s

[0051] Where ΔV is the change in hydraulic oil volume due to compression, V is the total volume of hydraulic oil in the oil passage, and K is the hydraulic oil elastic coefficient, K=1.5*10 -3 MPa -1 ΔP is the pressure increment caused by the compression of the hydraulic oil volume, A is the piston cross-sectional area, and s is the piston displacement.

[0052] Since the maximum pressure that piston II8 can withstand is 20MPa, the static seal on piston II8 does not need to be set with a retainer ring when the pressure is below 32MPa, but a retainer ring should be set when the pressure is above 32MPa. The present invention adopts a static sealing method of O-ring seal without setting a retainer ring. By selecting the length of the piston cavity where piston II8 is located and setting the sealing ball 6, the maximum axial displacement of piston II8 is 3mm, ensuring that the maximum working pressure of hydraulic oil in the oil passage is about 20MPa, thus ensuring that the maximum pressure of hydraulic oil is within the safe pressure range.

[0053] Furthermore, the wall thickness of the fixture body 1 at the flow channel 5a is taken as 1 mm. Finite element analysis shows that under no-load pressurization, with a wall thickness of 1 mm, the maximum radial expansion on one side of the thin wall is 33. The maximum stress at the thin-walled section will reach 300 MPa; with a wall thickness of 0.5 mm, the maximum radial expansion on one side of the thin-walled section is 61. The maximum stress at the thin-walled section will exceed 600 MPa; with a wall thickness of 2 mm, the maximum radial expansion on one side of the thin-walled section is 14. The maximum stress at the thin-walled section will reach 200 MPa.

[0054] An excessively small maximum expansion on one side necessitates high precision machining of the corresponding dimensions of the blank in the flexible wheel 7; otherwise, clamping will fail. An excessively large maximum expansion on one side will result in excessive working stress at the thin-walled section of the sealing cavity in the clamp body 1, leading to material fracture or premature fatigue damage. In this embodiment, a wall thickness of 1mm is used, and under no-load pressure of 16MPa, the maximum radial expansion on one side of the thin-walled section is 33. The maximum stress at the thin-walled section will reach 300MPa; the maximum single-sided expansion is appropriate, and the dimensional accuracy requirements for the corresponding part of the flexible wheel 7 blank are not high, so the adaptability is very good. The maximum stress of 300MPa at the thin-walled section is also within the allowable range of the material, thus meeting the usage requirements while ensuring sufficient service life.

[0055] Furthermore, a snap-fit ​​structure is provided at the left end of the clamp body 1 and the sealing cover 2 to ensure that the sealing surface will not undergo relative deformation under hydraulic oil pressure, thus preventing hydraulic oil leakage.

[0056] All surfaces of the fixture body 1 and the sealing cover 2 that mate are clearance fits. Under the action of high-pressure hydraulic oil, hydraulic oil will leak from the fit clearances. In order to ensure zero leakage of hydraulic oil during operation, anaerobic flat sealant is applied to the above mating surfaces during assembly.

[0057] To achieve high positioning accuracy, in addition to ensuring that the machining accuracy of the conical positioning reference surface at the right end of the fixture body 1 relative to the theoretical rotation center reaches 3... Within this range, the coaxiality error of the thin-walled inner hole at the left end flow channel 5a of the fixture body 1 relative to the theoretical center of rotation must not exceed 3. .

[0058] To meet the above requirements, the machining of fixture body 1 must adopt the following steps:

[0059] S1: Rough machining of bar stock:

[0060] S1-1: After unloading, clamp the outer circle of the left end of the bar stock and machine the right end face and outer cylindrical surface until flat.

[0061] S1-2: After unloading, clamp the outer circle of the right end and turn the left end face and the remaining outer cylindrical surface of the left end;

[0062] S1-3: Clamp the outer circle of the left end and drill the center hole of the right end tip; reverse the direction and clamp the outer circle of the right end, then drill the center hole of the left end tip.

[0063] S2: Preliminary processing and basic shaping:

[0064] S2-1: Using the center hole of the center point as the reference axis, initially machine the steps at both ends of the left and right sides;

[0065] S2-2: Turn the outer diameter of the middle flange to the dimensions shown in the drawing;

[0066] S2-3: Perform drilling operations:

[0067] - Drill 6 countersunk holes evenly distributed around the circumference of the flange;

[0068] - Drill screw holes evenly distributed around the circumference of the left end step.

[0069] - The flow channel 5d in the middle of the flange and the oil filling port.

[0070] S2-4: Machining thread limiting holes and turning pipe threads.

[0071] S2-5: Overall stress-relieving annealing treatment.

[0072] S3: High-precision datum surface machining:

[0073] S3-1: Using the center hole of the top as the reference axis, precision machine the tapered positioning surface on the right end to the accuracy shown in the drawing.

[0074] S4: Clamping and positioning adjustment:

[0075] S4-1: Fit the tapered surface of the right end of the part with the reference surface of the lathe flange;

[0076] S4-2: Use screws to rigidly fasten the flange to A2-6.

[0077] S5: Staged machining of the inner hole:

[0078] S5-1: Drill the left end hole → enlarge the hole → initial machining of the inner hole;

[0079] S5-2: Secondary stress-relief annealing;

[0080] S5-3: Finish machine the inner hole to the dimensions shown in the drawing, ensuring a coaxiality error ≤ 3. .

[0081] S6: Precision Fit Guarantee

[0082] S6-1: Measure the actual size of the blind hole at the left end;

[0083] S6-2: Custom-made zero-backlash precision cylindrical shaft, press-fitted into a blind hole to form an interference fit.

[0084] The technical scope of this utility model is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this utility model, and all such modifications and variations should fall within the protection scope of this utility model.

Claims

1. A high-precision hydraulic expansion fixture for flexible wheel machining, characterized in that, include: The fixture part includes a fixture body (1) and a sealing cover (2). The fixture body (1) is fixedly connected to the lathe flange, and the sealing cover (2) is sleeved along the axial direction of the fixture body (1). The oil circuit section is filled with hydraulic oil. The oil circuit section includes a flow channel (5)a and a transition oil circuit. The flow channel (5)a is located in the sealing gap formed by the fixture body (1) and the sealing cover (2). The flow channel (5)a and the transition oil circuit are connected. The deformation capacity of one side wall of the flow channel (5)a is higher than that of the other side. The starting unit is located at the port of the transition oil circuit and can move along the extension direction of the transition oil circuit to squeeze the hydraulic oil in the transition oil circuit to move to the flow channel (5)a.

2. The high-precision hydraulic expansion fixture for flexible wheel machining according to claim 1, characterized in that, The wall thickness of the clamp body (1) located on one side of the flow channel (5)a is less than the wall thickness of the sealing cover (2) on the other side. The deformation capacity of the clamp body (1) is higher than that of the sealing cover (2). The clamp body (1) is used to wrap around and clamp the outer wall of the flexible wheel (7).

3. The high-precision hydraulic expansion fixture for flexible wheel machining according to claim 1, characterized in that, The wall thickness of the clamp body (1) located on one side of the flow channel (5)a is greater than the wall thickness of the sealing cover (2) on the other side. The deformation capability of the clamp body (1) here is weaker than that of the sealing cover (2). The sealing cover (2) is used to externally support the inner wall of the flexible wheel (7).

4. A high-precision hydraulic expansion fixture for flexible wheel machining according to claim 1, characterized in that, The oil circuit section also includes interconnected flow channels (5)b, (5)c, (5)d and (5)e. A flow channel (5)a is formed between the annular groove on the outer arc surface of one end of the fixture body (1) and the inner wall of the sealing cover (2). A flow channel (5)c is provided inside the fixture body (1). A circular annular slit flow channel (5)b is provided at the end face step where the fixture body (1) and the sealing cover (2) cooperate. Flow channels (5)a, (5)b and (5)c are connected. Flow channel (5)d is connected to the oil injection port opened on the fixture body (1). Flow channel (5)e is connected to the piston chamber opened on the fixture body (1). A starting part is provided at the oil injection port and the piston chamber.

5. A high-precision hydraulic expansion fixture for flexible wheel machining according to claim 1 or 4, characterized in that, The starting part includes a piston I (4), which is detachably connected to the clamp body (1). A number of sealing rings are fitted on the piston I (4) inserted into the piston cavity. The piston I (4) is connected to the telescopic end of the telescopic component.

6. A high-precision hydraulic expansion fixture for flexible wheel machining according to claim 5, characterized in that, The flow channel (5)e and flow channel (5)d are coaxially arranged, and their axes are perpendicular to the axis of the piston chamber.

7. A high-precision hydraulic expansion fixture for flexible wheel machining according to claim 1 or 4, characterized in that, The starting part includes piston II (8), which is detachably connected to the clamp body (1). Piston II (8) fits against the end face of the oil inlet. The clamp body (1) is provided with a threaded limiting hole, which is coaxial with the oil inlet. A threaded plug (3) is threadedly connected in the threaded limiting groove. The threaded plug (3) is used to press piston II (8) against the end face of the oil inlet.

8. A high-precision hydraulic expansion fixture for flexible wheel machining according to claim 7, characterized in that, The piston II (8) has a flow channel (5)f that communicates with the flow channel (5)d. A sealing ball (6) for blocking the flow channel (5)f is placed between the flow channel (5)f and the threaded plug (3). The threaded plug (3) is used to press the sealing ball (6) at the port of the flow channel (5)f.

9. A high-precision hydraulic expansion fixture for flexible wheel machining according to claim 1, characterized in that, The gap between the clamp body (1) and the sealing cover (2) is filled with sealant.

10. A high-precision hydraulic expansion fixture for flexible wheel machining according to claim 1, characterized in that, The end of the fixture body (1) away from the flow channel (5)a is a truncated cone, with a taper of Morse code 2. The actual rotation center of the truncated cone has an error of less than 3 degrees relative to the theoretical rotation center. The coaxiality error of the clamping surface of the clamping body (1) or the sealing cover (2) used to clamp the flexible wheel (7) relative to the theoretical rotation center of the clamping body (1) is less than or equal to 3. .

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