Numerical control machining hydraulic clamp for weak rigidity connecting piece

Abstract

The utility model provides a weak-rigidity connecting piece numerical control machining hydraulic clamp which comprises a foundation plate 1, an equal-height pad 2, a rhombus positioning pin 3, a shoulder positioning device 4, an energy accumulator 5, a pressure gauge 6, a pressure maintaining block 7, a circular positioning pin 8, a threaded blind rivet 9, a cylinder score set 10, a guide block 11, an inner supporting rod 12, a floating expansion sleeve 13, a cover plate and a pull rod 14. A clamp nameplate is marked on the surface, and a counterbore used for being connected with a machine tool workbench is formed. The upper surface of the foundation plate 1 is provided with an equal-height pad 2, a rhombic positioning pin 3, a shoulder positioner 4, an energy accumulator 5, a pressure gauge 6, a pressure maintaining block 7, a circular positioning pin 8, a threaded blind rivet 9 and a pull cylinder group 10; the eight equal-height pads 2 are in a regular hexagon shape, are embedded into the foundation plate 1 in an interference fit mode, are equal to the shoulder positioner 4 in height and are used for increasing the contact area of a workpiece and the clamp and improving the clamping stability.

Description

Technical Field

[0001] This application relates to the field of tooling and fixtures, specifically to a hydraulic fixture for CNC machining of weakly rigid connecting parts. Background Technology

[0002] The main rotor hub connector, as the primary load-bearing component connecting the main rotor hub and the main rotor blades, directly affects the helicopter's flight performance. To meet performance requirements such as long service life and lightweight structure, titanium alloy is generally used. However, titanium alloy itself has a low elastic modulus and large elastic deformation, resulting in low efficiency and poor performance during CNC machining. This titanium alloy connector is difficult to machine, especially in terms of clamping stability.

[0003] The main propeller hub connector has a complex profile, resembling a long cylinder with deep, thin-walled grooves and a forked lug structure. During CNC machining, the material removal rate exceeds 80%, making it a typical weakly rigid structure with highly unstable machining conditions. Furthermore, the workpiece's complex structure requires high external shape coordination, and strict tolerances are imposed on assembly surfaces, hole systems, surface quality, and geometric tolerances, demanding extremely high manufacturing precision. Therefore, the tooling design is typically complex, requiring repeated adjustments during clamping, which introduces potential quality risks and increases operator workload, impacting machining efficiency. Thus, reducing quality risks and clamping stress in CNC machining, thereby improving clamping stability and ultimately enhancing product quality stability, is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0004] This application provides a hydraulic fixture for CNC machining of weakly rigid connecting parts, which can solve the problem of machining efficiency during clamping.

[0005] Technical solution: A CNC machining hydraulic fixture for weakly rigid connecting parts, the fixture comprising a base plate 1, a leveling pad 2, a diamond-shaped locating pin 3, a shoulder locator 4, an accumulator 5, a pressure gauge 6, a pressure holding block 7, a circular locating pin 8, a threaded tie 9, a cylinder assembly 10, a guide block 11, an inner support rod 12, a floating expansion sleeve 13, a cover plate, and a tie rod 14, wherein:

[0006] The base plate 1 is a fixture base, which is a rectangular metal plate with a fixture nameplate marked on its surface and countersunk holes for connecting to the machine tool worktable. The upper surface of the base plate 1 is provided with equal height pads 2, diamond-shaped positioning pins 3, shoulder positioning devices 4, accumulators 5, pressure gauges 6, pressure holding blocks 7, circular positioning pins 8, threaded rivets 9, and cylinder assembly 10.

[0007] The equal height pads 2 are regular hexagonal, totaling 8, and are embedded into the base plate 1 through interference fit, and are at the same height as the shoulder locator 4, in order to increase the contact area between the workpiece and the fixture and improve the clamping stability.

[0008] The rhomboid locating pin 3 and the circular locating pin 8 are diagonally distributed, with a diameter of 10mm, and fit tightly with the process hole of the workpiece to achieve workpiece clamping and positioning.

[0009] The shoulder locator 4 is in the shape of a ring, with 8 countersunk holes between the rings, and is connected to the base plate 1 by screws with a diameter of 6mm.

[0010] The threaded rivets 9 are 16mm in diameter, and there are a total of 2 rivets. They are used to screw into the process threaded holes of the workpiece and to position the workpiece against the shoulder locator 4 and the equalizing pad 2 by hydraulic drive.

[0011] The cylinder assembly 10 is connected to the base plate 1 by screws. The guide block 11, inner support rod 12, floating expansion sleeve 13, cover plate and tie rod 14 are arranged in sequence above the cylinder assembly 10 and are coaxial.

[0012] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes an accumulator 5, which is installed on the base plate 1 to compensate for leakage in the hydraulic system and maintain stable system pressure.

[0013] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes a pressure gauge 6, which is installed on the base plate 1 to monitor the system pressure value.

[0014] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes a pressure holding block 7, which is set on the base plate 1 and connected to the external hydraulic press pipeline to maintain the inlet pressure to the required outlet pressure.

[0015] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes an inner support rod 12, which passes through the guide block 11. A floating expansion sleeve 13 is located at the top of the inner support rod 12, which serves to limit the position of the floating expansion sleeve 13.

[0016] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes a cover plate and a tie rod 14. The cover plate and tie rod 14 are driven by the cylinder assembly 10 to contract and press the floating expansion sleeve 13. Under the support of the inner support rod 12, the floating expansion sleeve 13 expands to achieve auxiliary support for the workpiece.

[0017] In summary, the advantages of the hydraulic fixture for CNC machining of weakly rigid connecting parts provided in this application are as follows:

[0018] 1. This tooling invention uses hydraulically driven retraction of the rivet and pull rod, making clamping operation simple and greatly reducing the labor intensity of the operator;

[0019] 2. Unlike conventional clamping methods where the clamping force is applied to the workpiece body, the tooling of this invention applies the clamping force to the process platform reserved for the workpiece and uses a floating expansion sleeve for auxiliary support, which increases the clamping stability while reducing the stress deformation of the workpiece.

[0020] 3. This fixture uses one surface and two pins to directly position the workpiece, allowing the workpiece to be aligned once and the coordinate system to be repeatedly called, which greatly improves the workpiece clamping and alignment efficiency.

[0021] 4. Hydraulic clamping can achieve consistent clamping force, reduce the risk of clamping failures caused by different employee skills, and improve the stability of processing quality. Attached Figure Description

[0022] Figure 1 A schematic diagram of a hydraulic fixture for CNC machining of weakly rigid connecting parts provided in this application;

[0023] Figure 2 A schematic diagram of the main propeller hub connector;

[0024] Figure 3 A schematic diagram of the use of a hydraulic fixture for CNC machining of weakly rigid connecting parts provided in this application;

[0025] Attached reference numerals: 1-base plate, 2-level pad, 3-diamond-shaped locating pin, 4-shoulder locator, 5-accumulator, 6-pressure gauge, 7-pressure holding block, 8-circular locating pin, 9-threaded tie rod, 10-cylinder assembly, 11-guide block, 12-inner support rod, 13-floating expansion sleeve, 14-cover plate and tie rod. Detailed Implementation

[0026] Traditionally, clamping typically employs modular tooling, resulting in extremely low clamping efficiency. Multiple clamping operations are required for a single process, increasing the operator's workload. Furthermore, frequent disassembly and adjustments, along with changes in machining datum, increase the risk of deviations. To minimize the number of clamping operations, reduce clamping labor intensity, enhance clamping rigidity, and improve clamping efficiency and stability, a practical, effective, and rapid hydraulic tooling suitable for CNC machining of this workpiece is proposed.

[0027] Unlike conventional combination tooling fixtures that use bolts and pressure plates for manual clamping, requiring frequent adjustments to align the workpiece reference, the tooling described in this invention uses tension screws screwed into the pre-drilled process thread holes on the workpiece, and then fits the workpiece onto a support rod with a floating expansion sleeve. Hydraulic drive allows for one-click locking of the workpiece, minimizing workpiece stress deformation. Secondly, this tooling uses a single locating surface and two locating pins to directly align the workpiece coordinate system, significantly improving workpiece clamping and alignment efficiency. Furthermore, after a workpiece is successfully machined, subsequent workpieces do not require coordinate system alignment or coordinate compensation, greatly reducing the operator's workload and improving both clamping efficiency and the quality stability of batch production.

[0028] Example 1

[0029] like Figure 1As shown, this application provides a CNC machining hydraulic fixture for weakly rigid connecting parts, including a base plate 1, a leveling pad 2, a diamond-shaped locating pin 3, a shoulder locator 4, an accumulator 5, a pressure gauge 6, a pressure holding block 7, a circular locating pin 8, a threaded tie rod 9, a cylinder assembly 10, a guide block 11, an inner support rod 12, a floating expansion sleeve 13, a cover plate, and a tie rod 14, wherein:

[0030] The base plate 1 is a fixture base, which is a rectangular metal plate with a fixture nameplate marked on its surface and countersunk holes for connecting to the machine tool worktable; the leveling pad 2, diamond-shaped positioning pin 3, shoulder positioning device 4, accumulator 5, pressure gauge 6, pressure holding block 7, circular positioning pin 8, threaded pull stud 9, and cylinder assembly 10 are all set on the upper surface of the base plate 1.

[0031] The equal height pads 2 are regular hexagonal, totaling 8, and are embedded into the base plate 1 through interference fit, and are at the same height as the shoulder locator 4, in order to increase the contact area between the workpiece and the fixture and improve the clamping stability.

[0032] The rhomboid locating pin 3 and the circular locating pin 8 are diagonally distributed, with a diameter of 10mm, and fit tightly with the process hole of the workpiece to achieve workpiece clamping and positioning.

[0033] The shoulder locator 4 is in the shape of a ring, with 8 countersunk holes between the rings, and is connected to the base plate 1 by screws with a diameter of 6mm.

[0034] The threaded rivets 9 are 16mm in diameter, and there are a total of 2 rivets. They are used to screw into the process threaded holes of the workpiece and to position the workpiece against the shoulder locator 4 and the equalizing pad 2 by hydraulic drive.

[0035] The cylinder assembly 10 is connected to the base plate 1 by screws. The guide block 11, inner support rod 12, floating expansion sleeve 13, cover plate and tie rod 14 are arranged in sequence above the cylinder assembly 10 and are coaxial.

[0036] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes an accumulator 5, which is installed on the base plate 1 to compensate for leakage in the hydraulic system and maintain stable system pressure.

[0037] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes a pressure gauge 6, which is installed on the base plate 1 to monitor the system pressure value.

[0038] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes a pressure holding block 7, which is set on the base plate 1 and connected to the external hydraulic press pipeline to maintain the inlet pressure to the required outlet pressure.

[0039] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes an inner support rod 12, which passes through the guide block 11. A floating expansion sleeve 13 is located at the top of the inner support rod 12, which serves to limit the position of the floating expansion sleeve 13.

[0040] Specifically, the CNC machining hydraulic fixture for weakly rigid connecting parts also includes a cover plate and a tie rod 14. The cover plate and tie rod 14 are driven by the cylinder assembly 10 to contract and press the floating expansion sleeve 13. Under the support of the inner support rod 12, the floating expansion sleeve 13 expands to achieve auxiliary support for the workpiece.

[0041] It should be noted that the floating expansion sleeve 13 is made of rubber to prevent the expansion sleeve from scratching the inner wall of the workpiece.

[0042] Example 2

[0043] like Figure 3 As shown, this application provides a method for using a hydraulic fixture for CNC machining of weakly rigid connecting parts, including:

[0044] Step 1. Align the base plate 1 and use countersunk bolts to fix the fixture onto the CNC machining center worktable;

[0045] Step 2. Screw two tension screws 9 into the process hole reserved in the workpiece, and then put the workpiece with tension screws 9 on into the inner support rod 12 with floating expansion sleeve 13.

[0046] Step 3. Adjust the workpiece position. The rhomboid locating pin 3 and the circular locating pin 8 are respectively engaged with the workpiece locating pin hole and the rhomboid locating pin hole to achieve workpiece positioning.

[0047] Step 4. After adjusting the hydraulic press to the set pressure, connect the pressure holding block 7. Control the clamping force by observing the pressure gauge. The accumulator 5 keeps the pressure stable. Then drive the tension screw 9 to retract, so that the workpiece is close to the shoulder locator 4. Also drive the cover plate and the pull rod 14 to press the floating expansion sleeve 13 to expand it, so as to achieve auxiliary support.

[0048] Step 5. After the pressure gauge 6 reading stabilizes, remove the hydraulic press, clamping is complete, and then start CNC machining after aligning the workpiece coordinate system;

[0049] Step 6. After processing, release the pressure by adjusting the pressure holding block 7, take out the workpiece and unscrew the threaded rivet 9 to complete the processing; repeat this operation for the next workpiece clamping. The CNC program can be run directly using the coordinate system of the upper workpiece, without the need to repeat the coordinate system alignment operation.

[0050] In summary, the advantages of the hydraulic fixture for CNC machining of weakly rigid connecting parts provided in this application are as follows:

[0051] 1. This tooling invention uses hydraulically driven retraction of the rivet and pull rod, making clamping operation simple and greatly reducing the labor intensity of the operator;

[0052] 2. Unlike conventional clamping methods where the clamping force is applied to the workpiece body, the tooling of this invention applies the clamping force to the process platform reserved for the workpiece and uses a floating expansion sleeve for auxiliary support, which increases the clamping stability while reducing the stress deformation of the workpiece.

[0053] 3. This fixture uses one surface and two pins to directly position the workpiece, allowing the workpiece to be aligned once and the coordinate system to be repeatedly called, which greatly improves the workpiece clamping and alignment efficiency.

[0054] 4. Hydraulic clamping can achieve consistent clamping force, reduce the risk of clamping failures caused by different employee skills, and improve the stability of processing quality.

Claims

1. A CNC machining hydraulic fixture for weakly rigid connecting parts, characterized in that, The fixture includes a base plate (1), a leveling pad (2), a diamond-shaped locating pin (3), a shoulder locator (4), an accumulator (5), a pressure gauge (6), a pressure holding block (7), a circular locating pin (8), a threaded tie rod (9), a cylinder assembly (10), a guide block (11), an inner support rod (12), a floating expansion sleeve (13), a cover plate, and a tie rod (14), wherein: The base plate (1) is a fixture base, which is a rectangular metal plate with a fixture nameplate marked on its surface and countersunk holes for connecting to the machine tool worktable. The upper surface of the base plate (1) is provided with equal height pads (2), diamond-shaped locating pins (3), shoulder locators (4), accumulators (5), pressure gauges (6), pressure holding blocks (7), circular locating pins (8), threaded rivets (9), and cylinder assembly (10). The equal height pad (2) is a regular hexagon, with a total of 8 pads. It is embedded into the base plate (1) through interference fit and is at the same height as the shoulder locator (4) to increase the contact area between the workpiece and the fixture and improve the clamping stability. The rhomboid positioning pin (3) and the circular positioning pin (8) are diagonally distributed, with a diameter of 10mm, and are closely fitted with the process hole of the workpiece to achieve workpiece clamping and positioning; The shoulder locator (4) is in the shape of a ring, with 8 countersunk holes between the rings, and is connected to the base plate (1) by screws with a diameter of 6mm. The threaded rivets (9) are 16mm in diameter, and there are a total of 2 rivets. They are used to screw into the process threaded holes of the workpiece and to position the workpiece with the shoulder locator (4) and the equal height pad (2) by hydraulic drive. The cylinder assembly (10) is connected to the base plate (1) by screws. The guide block (11), inner support rod (12), floating expansion sleeve (13), cover plate and pull rod (14) are arranged above the cylinder assembly (10) in sequence and are coaxial.

2. The clamp according to claim 1, characterized in that, The CNC machining hydraulic fixture for weak rigid connectors also includes an accumulator (5), which is mounted on the base plate (1) to compensate for leakage in the hydraulic system and maintain stable system pressure.

3. The clamp according to claim 1, characterized in that, The CNC machining hydraulic fixture for weak rigid connectors also includes a pressure gauge (6), which is set on the base plate (1) to monitor the system pressure value.

4. The clamp according to claim 1, characterized in that, The CNC machining hydraulic fixture for weak rigid connectors also includes a pressure holding block (7), which is set on the base plate (1) and connected to the external hydraulic press pipeline to maintain the inlet pressure to the required outlet pressure.

5. The clamp according to claim 1, characterized in that, The CNC machining hydraulic fixture for weak rigid connectors also includes an inner support rod (12), which passes through the guide block (11). A floating expansion sleeve (13) is set at the top of the inner support rod (12) to limit the position of the floating expansion sleeve (13).

6. The clamp according to claim 1, characterized in that, The CNC machining hydraulic fixture for weak rigid connectors also includes a cover plate and a tie rod (14). The cover plate and tie rod (14) are driven by the cylinder assembly (10) to contract and press the floating expansion sleeve (13). Under the support of the inner support rod (12), the floating expansion sleeve (13) expands to achieve auxiliary support for the workpiece.

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