A hydraulic clamp with a mechanical self-locking structure and its design method

Abstract

This invention discloses a hydraulic clamp with a mechanical self-locking structure and its design method, comprising: a hydraulic cylinder and a hydraulic cylinder piston rod slidably disposed within the hydraulic cylinder; a self-locking assembly is disposed on the hydraulic cylinder, the self-locking assembly including a wedge-shaped locking pin, a push rod, a push-pull locking rod, and a wedge-shaped locking block; one end of the push-pull locking rod is axially connected to the push rod, and the other end is axially connected to the hydraulic cylinder piston rod; the wedge-shaped locking pin is disposed on the outer wall of the push-pull locking rod, the wedge-shaped locking block is sleeved on the outer side of the push rod, and the inner wall of the wedge-shaped locking block is provided with a wedge-shaped groove, the wedge-shaped groove being adapted to the shape of the wedge-shaped locking pin; the wedge-shaped locking pin extends from the push-pull locking rod to the wedge-shaped locking block, and the wedge-shaped locking pin is inserted into the wedge-shaped groove; when the hydraulic cylinder is cut off, the wedge-shaped locking pin and the wedge-shaped groove of the wedge-shaped locking block form a rigid engagement, the push-pull locking rod maintains the relative position of the push rod and the hydraulic cylinder piston rod, and the whole remains locked, achieving continuous clamping, eliminating the need for continuous oil supply of electricity / fuel consumption, and reducing energy costs.

Description

Technical Field

[0001] This invention relates to the field of automated clamps, and in particular to a hydraulic clamp with a mechanical self-locking structure and its design method. Background Technology

[0002] In the field of automated clamping, traditional hydraulic clamps rely on a continuous oil supply to maintain oil pressure in order to ensure the workpiece is clamped, which has the following key drawbacks:

[0003] 1. High energy consumption: In order to prevent the workpiece from loosening, the hydraulic system needs to run continuously to supply oil. Even if the workpiece is clamped, a large amount of hydraulic oil and driving energy are still consumed, which does not meet the energy-saving requirements.

[0004] 2. Reliance on continuous hydraulic pressure: Once the oil circuit is interrupted or the hydraulic pump fails, the oil pressure disappears, the clamping force drops immediately, causing the workpiece to shift, affecting the machining accuracy and causing safety accidents;

[0005] 3. High component load: Continuous oil supply keeps the cylinder piston rod and oil pipeline under high pressure for a long time, which can easily cause component fatigue damage and shorten service life;

[0006] 4. Elastic pressure clamping: The clamping force is determined by the continuous hydraulic pressure. If the reverse force exceeds the hydraulically set clamping force, the workpiece will move in the opposite direction. If the clamping force is too large, the workpiece will be deformed. If the clamping force is too small, the workpiece will move due to the reverse force.

[0007] The core reason for the above problems is that traditional hydraulic clamps lack a rigid locking mechanism when the oil supply is cut off, and cannot maintain the clamping state after the oil supply is stopped, resulting in energy waste and insufficient reliability. Therefore, a hydraulic clamp with a mechanical self-locking structure and its design method are proposed to solve the above problems. Summary of the Invention

[0008] This invention overcomes the shortcomings of the prior art and provides a hydraulic clamp with a mechanical self-locking structure and its design method.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a hydraulic clamp with a mechanical self-locking structure, comprising: a hydraulic cylinder and a hydraulic cylinder piston rod slidably disposed in the hydraulic cylinder, the hydraulic cylinder being provided with a self-locking assembly, the self-locking assembly comprising a wedge-shaped locking pin, a push rod, a push-pull locking rod, and a wedge-shaped locking block, one end of the push-pull locking rod being axially connected to the push rod, and the other end being axially connected to the hydraulic cylinder piston rod;

[0010] The wedge-shaped locking pin is circumferentially disposed on the outer wall of the push-pull locking rod, the wedge-shaped locking block is sleeved on the outside of the push rod, the inner wall of the wedge-shaped locking block is provided with a wedge-shaped groove, the wedge groove is adapted to the shape of the wedge-shaped locking pin, the wedge-shaped locking pin extends from the push-pull locking rod to the wedge-shaped locking block, and the wedge-shaped locking pin can be inserted into the wedge groove;

[0011] When the oil cylinder is cut off, the wedge-shaped locking pin and the wedge-shaped locking block form a rigid engagement, and the push-pull locking rod maintains the relative position of the push rod and the piston rod of the oil cylinder, thereby maintaining the overall locked state and achieving continuous pressing without the need for continuous oil supply.

[0012] In a preferred embodiment of the present invention, the push-pull locking rod is a tapered structure, and the tapered structure gradually increases in size along the direction of travel of the push-pull locking rod.

[0013] In a preferred embodiment of the present invention, a step is provided on the push-pull locking rod, and the step is located at the end of the conical structure.

[0014] In a preferred embodiment of the present invention, the wedge-shaped locking pin is provided with two contact surfaces, a first contact surface and a second contact surface. When the push-pull locking rod moves, it first contacts the first contact surface to form a preliminary locking mechanism.

[0015] As it continues to move forward and comes into contact with the second contact surface, the larger the contact area with the second contact surface, the stronger the locking force formed.

[0016] When the push-pull locking rod contacts the first and second surfaces, the wedge-shaped locking pin moves along the wedge-shaped groove.

[0017] In a preferred embodiment of the present invention, the wedge angle of the wedge locking pin is β, and β satisfies tanβ≤μ (μ is the friction coefficient between the wedge locking pin and the wedge groove).

[0018] In a preferred embodiment of the present invention, the two ends of the push-pull locking rod are tapered structures, and the connection end between the push rod and the push-pull locking rod is provided with a tapered groove. The tapered groove is adapted to the tapered end of the push-pull locking rod, and the push-pull locking rod is inserted into the tapered groove and connected to the push rod.

[0019] In a preferred embodiment of the present invention, the piston rod of the hydraulic cylinder is provided with an end inner hole, the shape of which is adapted to the tapered end of the push-pull locking rod, and the push-pull locking rod is inserted into the end inner hole and connected to the piston rod of the hydraulic cylinder.

[0020] In a preferred embodiment of the present invention, a connecting block is provided between the hydraulic cylinder and the self-locking assembly, and the connecting block is fixed between the wedge-shaped locking block and the hydraulic cylinder housing to achieve a rigid connection between the hydraulic cylinder and the self-locking assembly.

[0021] In a preferred embodiment of the present invention, the free end of the self-locking component is connected to a clamping actuation component, the clamping actuation component includes a clamping arm and a pressure plate, one end of the clamping arm is connected to the outer wall of the wedge-shaped locking block, and the other end is detachably connected to the pressure plate.

[0022] In a preferred embodiment of the present invention, the pressure plate is detachably connected to the free end of the push rod, and the pressure plate is used to contact and press the workpiece.

[0023] In a preferred embodiment of the present invention, the diameter d of the push-pull locking rod is 8-15mm, the taper of the tapered end is 1:10-1:15, and the taper of the tapered groove is consistent with the tapered end of the push-pull locking rod to ensure the stability and shear strength of the two insertion fit.

[0024] Another technical solution adopted by the present invention is a design method for a hydraulic clamp with a mechanical self-locking structure, used for the design of the aforementioned hydraulic clamp with a mechanical self-locking structure, comprising the following steps:

[0025] S1: Requirements Analysis: Determine the target clamping force F, clamping stroke H, and continuous clamping time T after oil cut-off, and clarify the contact area requirements between the pressure plate and the workpiece;

[0026] S2: Determine the assembly relationship of the self-locking components: the tapered fit of the push-pull locking rod and the push rod, the wedge-shaped locking pin and the wedge-shaped locking block, and the connecting block connects the hydraulic cylinder and the self-locking components;

[0027] S3: Component selection: Select the cylinder piston rod diameter D, wedge locking pin material, push-pull locking rod diameter d and material, wedge locking block material, connecting block material, and pressure plate material according to requirements;

[0028] S4: Calculation of key parameters: Calculation of wedge locking pin and wedge groove dimensions, strength verification of tapered fit of push-pull locking rod, strength of connecting block and hydraulic pressure matching;

[0029] S5: Prototype Manufacturing and Testing: Manufacturing a prototype, testing the continuous pressing time after oil cut-off, reverse impact resistance performance, and energy consumption data to verify whether it meets the requirements;

[0030] S6: Optimization and Iteration: Adjust parameters such as wedge angle β, taper of push-pull locking rod tapered end, and connecting block thickness according to test results until the performance meets the standards.

[0031] In a preferred embodiment of the present invention, the calculation of key parameters in step S4 includes:

[0032] Calculation of wedge locking pin and wedge groove dimensions: The effective locking length L1 of the wedge locking pin is L1 = H / sinβ (H is the clamping stroke). The depth of the wedge groove is 5-10mm larger than the effective locking length of the wedge locking pin (to allow for insertion). The width of the wedge groove is compatible with the width of the wedge locking pin to meet the clearance requirements.

[0033] Strength check of the tapered fit of the push-pull locking rod: Shear force Q = F × sinβ (F is the clamping force), shear stress τ = 4Q / (πd²), τ ≤ [τ] ([τ] is the allowable shear force of the push-pull locking rod material); At the same time, check the compressive stress σ of the tapered mating surface σ = F / A (A is the projected area of ​​the tapered mating surface), σ ≤ [σ] ([σ] is the allowable compressive stress of the material).

[0034] Calculation of connecting block strength: The pressure F1 borne by the connecting block is F×cosβ, and the thickness of the connecting block is t=F1 / (b×[σ_b]) (b is the width of the connecting block, and [σ_b] is the allowable bending stress of the connecting block material). It is required that t≥10mm.

[0035] Hydraulic pressure matching calculation: Hydraulic pressure P=F / S (S is the force-bearing area of ​​the cylinder piston rod, S=πD² / 4).

[0036] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0037] Traditional hydraulic clamps rely on a continuous hydraulic pump to maintain oil pressure and ensure the workpiece is clamped. If the oil supply is interrupted (e.g., due to oil circuit leakage or pump malfunction), the pressure drop can cause the workpiece to loosen, leading to machining accuracy deviations or even safety accidents. This invention's self-locking assembly utilizes a dual locking mechanism: a rigid engagement of a wedge-shaped locking pin and a wedge-shaped groove, plus a push-pull locking rod positioning the relative position of the push rod and the cylinder piston rod. This mechanism maintains the overall locked state even after the cylinder's oil supply is interrupted, achieving long-term clamping without continuous oil supply. This solves the problem of "failure upon pressure loss" in traditional structures, ensuring the continuity and stability of the machining process.

[0038] Meanwhile, this invention continues to operate even after the oil supply is cut off, which greatly reduces the energy consumption of the hydraulic system. Under the same pressing conditions, it eliminates the need for electricity / fuel consumption for continuous oil supply. Long-term use can significantly reduce energy costs. It also reduces the working time of the hydraulic pump, reduces the wear of the pump body and oil circuit, extends the maintenance cycle of the hydraulic system, and indirectly reduces equipment operation and maintenance costs.

[0039] In addition, the present invention features a compact layout in which the push-pull locking rod is axially connected to the push rod and the cylinder piston rod, and the wedge-shaped locking block is sleeved on the outside of the push rod. This avoids the problems of large space occupation and complex assembly caused by the traditional multi-component dispersed design. It can be adapted to the narrow installation space in automated production lines. The rigid locking method of wedge-shaped locking pin and wedge-shaped groove shape matching + axial positioning of push-pull locking rod has stronger resistance to lateral impact and higher locking accuracy compared with the flexible locking of simple hydraulic pressure holding.

[0040] (2) The tapered structure of the push-pull locking rod of the present invention utilizes the principle of inclined plane stroke conversion to convert the linear pressing stroke H of the hydraulic cylinder piston rod into the effective locking stroke L1 of the wedge locking pin through the wedge angle β (L1=H / sinβ). Compared with the 1:1 stroke transmission of the traditional equal diameter rod, the tapered structure can significantly shorten the rod length under the same pressing effect, and meet the pressing stroke requirements without designing an extra-long rod, thereby reducing the overall equipment volume and adapting to narrow working spaces.

[0041] Meanwhile, the conical structure, through the principle of force saving by the inclined plane, transforms the basic clamping force F output by the hydraulic cylinder into an amplified locking force. When the taper is 1:10, a force amplification ratio of 1:10 can be achieved (compared to 1:1 for traditional equal-diameter rods). This means that a small hydraulic cylinder output can obtain a large clamping force. As the push-pull locking rod moves forward, the contact area between the wedge-shaped locking pin and the second contact surface gradually increases. Combined with the wedge angle β satisfying the self-locking condition of tanβ≤μ, the locking force increases synchronously with the stroke, ultimately forming a rigidly locked state. The step and the end face limit cooperation of the wedge-shaped locking block prevent the push-pull locking rod from retracting towards the hydraulic cylinder. Combined with the self-locking characteristics of the wedge structure, the locking state is doubly guaranteed to remain secure. Even after the oil is cut off, the clamping force can still be maintained. Through the synergistic cooperation of the conical structure, double contact surface, and step, the problem of long stroke in traditional hydraulic clamps is solved, and the precise amplification and stable locking of the clamping force are achieved. At the same time, workpiece protection and operational reliability are taken into account, and the clamping force can still be maintained even when the oil is cut off.

[0042] (3) Step S1 of the present invention clearly determines the target clamping force F, clamping stroke H, oil cut-off continuous clamping time T and oil saving rate target, and at the same time clarifies the contact area requirements between the pressure plate and the workpiece, transforming the abstract usage requirements into specific design indicators from the source, ensuring that the subsequent component selection and parameter calculation are all centered around the actual application scenario, and improving the adaptability of the equipment to different processing scenarios.

[0043] Meanwhile, step S2 clarifies the tapered fit of the push-pull locking rod and push rod, the wedge fit of the wedge locking pin and wedge locking block, and the connection method of the connecting block, standardizing the assembly logic of the core components. Then, step S4 calculates the dimensions of the wedge locking pin and wedge groove, checks the strength of the push-pull locking rod, and matches the hydraulic pressure, quantifying key parameters (such as effective locking length L1=H / sinβ, shear stress τ≤[τ]), avoiding deviations in empirical design, ensuring that the locking performance and structural strength of the self-locking component meet the standards, and avoiding the risk of failure in later use. Attached Figure Description

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0045] Figure 1 This is a three-dimensional structural diagram of a hydraulic clamping device with a mechanical self-locking structure according to a preferred embodiment of the present invention;

[0046] Figure 2 This is an exploded view of a hydraulic clamping device with a mechanical self-locking structure according to a preferred embodiment of the present invention;

[0047] Figure 3 This is a three-dimensional structural diagram of another hydraulic clamp with a mechanical self-locking structure according to a preferred embodiment of the present invention;

[0048] Figure 4 This is a preferred embodiment of the present invention. Figure 3 Top view sectional view;

[0049] Figure 5 This is one of the preferred embodiments of the present invention, showing the relationship between the wedge-shaped locking pin and the push-pull locking rod.

[0050] Figure 6 This is the second diagram showing the travel relationship between the wedge-shaped locking pin and the push-pull locking rod in a preferred embodiment of the present invention;

[0051] Figure 7 This is the third diagram showing the travel relationship between the wedge-shaped locking pin and the push-pull locking rod in a preferred embodiment of the present invention;

[0052] Figure 8 This is a flowchart illustrating the design method of a hydraulic clamping device with a mechanical self-locking structure, which is a preferred embodiment of the present invention.

[0053] In the diagram: 1. Hydraulic cylinder; 2. Hydraulic cylinder piston rod; 3. Self-locking assembly; 30. Wedge locking pin; 300. First contact surface; 301. Second contact surface; 31. Push rod; 310. Conical groove; 32. Push-pull locking rod; 320. Step; 33. Wedge locking block; 330. Wedge groove; 4. Connecting block; 5. Pressing actuation assembly; 50. Pressing arm; 51. Pressure plate. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or it can be fixed through another intermediate component. When a component is said to be "connected to" another component, it can be directly connected to the other component or it may be fixed through another intermediate component. When a component is said to be "set on" another component, it can be set directly on the other component or it may be set through another intermediate component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] like Figures 1 to 4 As shown, a hydraulic clamp with a mechanical self-locking structure includes: a hydraulic cylinder 1 and a hydraulic cylinder piston rod 2 slidably disposed in the hydraulic cylinder 1. A self-locking assembly 3 is provided on the hydraulic cylinder 1. The self-locking assembly 3 includes a wedge-shaped locking pin 30, a push rod 31, a push-pull locking rod 32, and a wedge-shaped locking block 33. One end of the push-pull locking rod 32 is axially connected to the push rod 31, and the other end is axially connected to the hydraulic cylinder piston rod 2.

[0058] The wedge-shaped locking pin 30 is circumferentially disposed on the outer wall of the push-pull locking rod 32, and the wedge-shaped locking block 33 is sleeved on the outside of the push rod 31. The inner wall of the wedge-shaped locking block 33 is provided with a wedge-shaped groove 330, which is adapted to the shape of the wedge-shaped locking pin 30. The wedge-shaped locking pin 30 extends from the push-pull locking rod 32 to the wedge-shaped locking block 33, and the wedge-shaped locking pin 30 can be inserted into the wedge-shaped groove 330.

[0059] When the oil cylinder 1 is cut off, the wedge-shaped locking pin 30 and the wedge-shaped groove 330 of the wedge-shaped locking block 33 form a rigid engagement. The push-pull locking rod 32 maintains the relative position of the push rod 31 and the piston rod 2 of the oil cylinder, thereby maintaining the overall locked state and achieving continuous pressing without the need for continuous oil supply.

[0060] Traditional hydraulic clamps rely on a continuous hydraulic pump to maintain oil pressure and ensure the workpiece is clamped. If the oil supply is interrupted (e.g., due to oil circuit leakage or pump malfunction), the pressure drop can cause the workpiece to loosen, leading to machining accuracy deviations or even safety accidents. The self-locking assembly 3 of this invention employs a dual locking mechanism: a rigid engagement of the wedge-shaped locking pin 30 and the wedge-shaped groove 330, plus a push-pull locking rod 32 positioning the push rod 31 relative to the piston rod 2 of the cylinder. This mechanism maintains the overall locked state even after the oil supply to the cylinder 1 is interrupted, achieving long-term clamping without continuous oil supply. This solves the problem of "failure upon pressure loss" in traditional structures, ensuring the continuity and stability of the machining process.

[0061] Meanwhile, this invention continues to operate even after the oil supply is cut off, which greatly reduces the energy consumption of the hydraulic system. Under the same pressing conditions, it eliminates the need for electricity / fuel consumption for continuous oil supply. Long-term use can significantly reduce energy costs. It also reduces the working time of the hydraulic pump, reduces the wear of the pump body and oil circuit, extends the maintenance cycle of the hydraulic system, and indirectly reduces equipment operation and maintenance costs.

[0062] In addition, the push-pull locking rod 32 of the present invention is axially connected to the push rod 31 and the oil cylinder piston rod 2, and the wedge-shaped locking block 33 is sleeved on the outside of the push rod 31 in a compact layout. This avoids the problems of large space occupation and complicated assembly caused by the traditional multi-component dispersed design. It can be adapted to the narrow installation space in the automated production line. The rigid locking method of wedge-shaped locking pin 30 and wedge-shaped groove 330 with shape adaptation + axial positioning of push-pull locking rod 32 has stronger resistance to lateral impact and higher locking accuracy compared with the flexible locking of simple hydraulic pressure holding.

[0063] like Figure 5-8 As shown, the push-pull locking rod 32 has a tapered structure, which gradually increases in size along the direction of travel. A step 320 is provided on the push-pull locking rod 32, and the step 320 is located at the end of the tapered structure. The wedge-shaped locking pin 30 has two contact surfaces, a first contact surface 300 and a second contact surface 301. When the push-pull locking rod 32 travels, it first contacts the first contact surface 300 to form a preliminary locking mechanism; it continues to travel and contacts the second contact surface 301. The larger the contact surface with the second contact surface 301, the stronger the locking force. When the push-pull locking rod 32 contacts the first and second surfaces, the wedge-shaped locking pin 30 moves along the wedge groove 330. The wedge angle of the wedge-shaped locking pin 30 is β, and β satisfies tanβ≤μ (μ is the coefficient of friction between the wedge-shaped locking pin 30 and the wedge groove 330).

[0064] Specifically, the push-pull locking rod 32 has a tapered structure and a wedge-shaped locking pin 30 with double contact surfaces: the push-pull locking rod 32 adopts a tapered structure with a ratio of 1:10 to 1:15, which gradually increases in size along the direction of travel. It forms a linkage with the first and second contact surfaces 301 of the wedge-shaped locking pin 30. When the hydraulic cylinder 1 drives the piston rod to move the push-pull locking rod 32 forward, the inclined surface of the tapered structure will push the wedge-shaped locking pin 30 to move synchronously along the wedge groove 330 of the wedge-shaped locking block 33. It first fits against the first contact surface 300 to achieve initial positioning, and then fully fits against the second contact surface 301 as the stroke progresses. The contact area increases with the stroke.

[0065] The push-pull locking rod 32 step 320 cooperates with the conical structure and wedge groove 330: The step 320 is set at the end of the conical structure. When the push-pull locking rod 32 moves to the preset pressing position, the step 320 and the end face of the wedge locking block 33 form a mechanical limit. At the same time, the wedge locking pin 30 and the wedge groove 330 complete rigid engagement. The three together constitute the linkage mechanism of "conical drive - double contact surface locking - step 320 limit".

[0066] The tapered structure of the push-pull locking rod 32 utilizes the principle of inclined plane stroke conversion to transform the linear pressing stroke H of the hydraulic cylinder piston rod 2 into the effective locking stroke L1 of the wedge locking pin 30 (L1=H / sinβ) through the wedge angle β. Compared with the 1:1 stroke transmission of the traditional equal-diameter rod, the tapered structure (such as 1:10 taper) can significantly shorten the rod length for the same pressing effect, eliminating the need to design an extra-long rod to meet the pressing stroke requirements, reducing the overall equipment size, and adapting to confined working spaces.

[0067] The tapered structure matches the taper of the wedge groove 330, ensuring smooth stroke transition. Combined with the double-contact guide of the wedge locking pin 30, it further enhances the accuracy of stroke transmission.

[0068] At the same time, it also meets the requirements of amplified and progressively increasing clamping force, resulting in a strong and long-lasting locking effect.

[0069] Implementation logic: ① Force amplification effect: The conical structure, through the principle of force saving by the inclined plane, transforms the basic clamping force F output by the hydraulic cylinder 1 into an amplified locking force. When the taper is 1:10, a force amplification ratio of 1:10 can be achieved (the traditional equal diameter rod is 1:1), that is, a small output pressure from the hydraulic cylinder 1 can obtain a super large clamping force; ② Increasing locking force: As the push-pull locking rod 32 moves, the contact area between the wedge locking pin 30 and the second contact surface 301 gradually increases. Combined with the wedge angle β satisfying the self-locking condition of tanβ≤μ, the locking force increases synchronously with the stroke, eventually forming a rigid locking state; ③ Anti-retraction guarantee: The step 320 and the end face limit cooperation of the wedge locking block 33 prevent the push-pull locking rod 32 from retracting towards the hydraulic cylinder 1. Combined with the self-locking characteristics of the wedge structure, the locking state is doubly guaranteed to remain secure, and the clamping force can still be maintained after the oil is cut off.

[0070] In addition, it also has the effect of strong compressive force adaptability, avoiding damage or loosening of the workpiece.

[0071] Implementation logic: ① Controllable amplification design: By designing the taper (1:10-1:15) and wedge angle β of the push-pull locking rod 32, the amplification ratio of the clamping force can be precisely adjusted, avoiding the problem of workpiece loosening due to insufficient pressure in traditional hydraulic clamps. ② Uniform rigidity transmission: The rigid connection between the tapered structure and the wedge fit allows the clamping force to be uniformly transmitted to the workpiece contact surface through the pressure plate 51, avoiding local pressure concentration and further protecting the workpiece. ③ Adaptability to different needs: By adjusting the taper and wedge angle parameters, it can adapt to the clamping force requirements of different workpieces, making it highly versatile.

[0072] Through the coordinated operation of "conical structure - double contact surface - 320 step", it not only solves the problems of long stroke and bulky structure of traditional hydraulic clamps, but also achieves precise amplification and stable locking of clamping force. At the same time, it takes into account workpiece protection and operational reliability. It can continue to clamp even when the oil is cut off, saving energy and adapting to a variety of operating scenarios.

[0073] In a preferred embodiment of the present invention, the push-pull locking rod 32 has tapered structures at both ends. The connection end between the push rod 31 and the push-pull locking rod 32 is provided with a tapered groove 310. The tapered groove 310 is adapted to the tapered end of the push-pull locking rod 32. The push-pull locking rod 32 is inserted into the tapered groove 310 and connected to the push rod 31. The diameter d of the push-pull locking rod 32 is 8-15mm, and the taper of the tapered end is 1:10-1:15. The taper of the tapered groove 310 is consistent with the tapered end of the push-pull locking rod 32 to ensure the stability and shear strength of the insertion and engagement between the two.

[0074] The piston rod 2 of the hydraulic cylinder is provided with an end inner hole. The shape of the end inner hole is adapted to the tapered end of the push-pull locking rod 32. The push-pull locking rod 32 is inserted into the end inner hole and connected to the piston rod 2 of the hydraulic cylinder.

[0075] In a preferred embodiment of the present invention, a connecting block 4 is provided between the hydraulic cylinder 1 and the self-locking component 3. The connecting block 4 is fixed between the wedge-shaped locking block 33 and the outer shell of the hydraulic cylinder 1, so as to realize the rigid connection between the hydraulic cylinder 1 and the self-locking component 3 and avoid the locking deviation caused by the relative displacement between the components.

[0076] In a preferred embodiment of the present invention, the free end of the self-locking component 3 is connected to the clamping execution component 5. The clamping execution component 5 includes a clamping arm 50 and a pressure plate 51. One end of the clamping arm 50 is connected to the outer wall of the wedge-shaped locking block 33, and the other end is detachably connected to the pressure plate 51. The pressure plate 51 is detachably connected to the free end of the push rod 31. The pressure plate 51 is used to contact and clamp the workpiece.

[0077] The pressure plate 51 and push rod 31 are detachably connected, and the clamping arm 50 and wedge locking block 33 are flexibly fixed. Different specifications of pressure plate 51 can be quickly replaced according to the size and material of the workpiece (such as polyurethane pressure plate 51 to prevent aluminum alloy workpieces from being crushed, and metal pressure plate 51 to adapt to high-strength workpieces), without the need to replace the entire clamping device. At the same time, by adjusting the clamping force F and clamping stroke H, it can adapt to different clamping requirements from light parts to heavy components, greatly improving the applicability of the equipment and reducing the equipment investment cost for enterprises in multi-scenario processing.

[0078] When using this invention,

[0079] The hydraulic pump is turned on, and the solenoid directional valve is energized in the forward direction to allow hydraulic oil to enter the rodless chamber of cylinder 1, driving the piston rod 2 of the cylinder to extend axially. When the piston rod 2 extends, it moves synchronously with the push-pull locking rod 32 through the engagement of the inner hole at its end with the tapered end of the push-pull locking rod 32. The other end of the push-pull locking rod 32 engages with the push rod 31 through the tapered groove 310, pushing the push rod 31 to move towards the workpiece, thereby causing the pressure plate 51 at the free end of the push rod 31 to approach the workpiece.

[0080] During the movement of the push rod 31, the wedge-shaped locking pin 30, which is circumferentially set on the outer wall of the push-pull locking rod 32, extends towards the wedge-shaped locking block 33 along with the push-pull locking rod 32 and gradually inserts into the wedge-shaped groove 330 on the inner wall of the wedge-shaped locking block 33. When the pressure plate 51 contacts the workpiece and reaches the set clamping force (such as 3-40kN, which can be adjusted according to the requirements), the wedge-shaped locking pin 30 is completely engaged in the wedge groove 330, forming a rigid engagement.

[0081] After the set clamping force is reached, the hydraulic pump is turned off, the solenoid directional valve is de-energized, and the oil supply to cylinder 1 is cut off. At this time, the wedge locking pin 30 forms a self-locking mechanism because the wedge angle β satisfies tanβ≤μ (μ is the coefficient of friction), and the push-pull locking rod 32 maintains the relative position of the push rod 31 and the cylinder piston rod 2 through the tapered fit. The self-locking assembly 3 as a whole maintains the locked state, realizing continuous clamping of the workpiece without the need for continuous oil supply.

[0082] After processing, the hydraulic pump is turned on, and the solenoid directional valve is energized in reverse to allow hydraulic oil to enter the rod chamber of cylinder 1, driving the cylinder piston rod 2 to retract axially. When the cylinder piston rod 2 retracts, it pulls the push-pull locking rod 32 back simultaneously, causing the tapered structures at both ends of the push-pull locking rod 32 to disengage from the tapered groove 310 of the push rod 31 and the end inner hole of the cylinder piston rod 2, respectively. At the same time, the push-pull locking rod 32 drives the wedge locking pin 30 to exit from the wedge groove 330 of the wedge locking block 33, releasing the rigid engagement. The push rod 31 retracts with the push-pull locking rod 32, driving the pressure plate 51 to disengage from the workpiece, until the cylinder piston rod 2 is fully retracted to the initial position. The hydraulic pump is then turned off, completing the unlocking process.

[0083] like Figure 8As shown, a design method for a hydraulic clamp with a mechanical self-locking structure, used in the design of the aforementioned hydraulic clamp with a mechanical self-locking structure, includes the following steps:

[0084] S1: Requirements Analysis: Determine the target clamping force F, clamping stroke H, oil cut-off continuous clamping time T, and oil saving rate target, and clarify the contact area requirements between the pressure plate and the workpiece;

[0085] S2: Determine the assembly relationship of the self-locking components: the tapered fit of the push-pull locking rod and the push rod, the wedge-shaped locking pin and the wedge-shaped locking block, and the connecting block connects the hydraulic cylinder and the self-locking components;

[0086] S3: Component selection: Select the cylinder piston rod diameter D, wedge locking pin material, push-pull locking rod diameter d and material, wedge locking block material, connecting block material, and pressure plate material according to requirements;

[0087] S4: Calculation of key parameters: Calculation of wedge locking pin and wedge groove dimensions, strength verification of tapered fit of push-pull locking rod, strength of connecting block and hydraulic pressure matching;

[0088] S5: Prototype Manufacturing and Testing: Manufacturing a prototype, testing the continuous pressing time after oil cut-off, reverse impact resistance performance, and energy consumption data to verify whether it meets the requirements;

[0089] S6: Optimization and Iteration: Adjust parameters such as wedge angle β, taper of push-pull locking rod tapered end, and connecting block thickness according to test results until the performance meets the standards.

[0090] In a preferred embodiment of the present invention, the calculation of key parameters in step S4 includes:

[0091] Calculation of wedge locking pin and wedge groove dimensions: The effective locking length L1 of the wedge locking pin is L1 = H / sinβ (H is the clamping stroke). The depth of the wedge groove is 5-10mm greater than the effective locking length of the wedge locking pin (to allow for insertion). The width of the wedge groove is compatible with the width of the wedge locking pin, satisfying the clearance fit (0.02-0.05mm).

[0092] Strength check of the tapered fit of the push-pull locking rod: Shear force Q = F × sinβ (F is the clamping force), shear stress τ = 4Q / (πd²), τ ≤ [τ] ([τ] is the allowable shear force of the push-pull locking rod material); At the same time, check the compressive stress σ of the tapered mating surface σ = F / A (A is the projected area of ​​the tapered mating surface), σ ≤ [σ] ([σ] is the allowable compressive stress of the material).

[0093] Calculation of connecting block strength: The pressure F1 borne by the connecting block is F×cosβ, and the thickness of the connecting block is t=F1 / (b×[σ_b]) (b is the width of the connecting block, and [σ_b] is the allowable bending stress of the connecting block material). It is required that t≥10mm.

[0094] Hydraulic pressure matching calculation: Hydraulic pressure P=F / S (S is the force-bearing area of ​​the cylinder piston rod, S=πD² / 4).

[0095] Step S1 clearly defines the target clamping force F, clamping stroke H, oil cut-off continuous clamping time T, and oil saving rate target. At the same time, it clarifies the contact area requirements between the pressure plate and the workpiece, transforming abstract usage requirements into specific design indicators from the source. This ensures that subsequent component selection and parameter calculations are all based on actual application scenarios, improving the equipment's adaptability to different processing scenarios.

[0096] Meanwhile, step S2 clarifies the tapered fit of the push-pull locking rod and push rod, the wedge fit of the wedge locking pin and wedge locking block, and the connection method of the connecting block, standardizing the assembly logic of the core components. Then, step S4 calculates the dimensions of the wedge locking pin and wedge groove, checks the strength of the push-pull locking rod, and matches the hydraulic pressure, quantifying key parameters (such as effective locking length L1=H / sinβ, shear stress τ≤[τ]), avoiding deviations in empirical design, ensuring that the locking performance and structural strength of the self-locking component meet the standards, and avoiding the risk of failure in later use.

[0097] Example 1: Design of a hydraulic clamping device for machining automotive aluminum alloy gearbox housings

[0098] S1: Requirements Analysis: For the clamping requirements of automotive aluminum alloy gearbox housings (material 6061-T6, weight 8kg, machined surface flatness requirement ≤0.02mm), determine the core design parameters:

[0099] The target clamping force is F = 8kN (to avoid damaging the aluminum alloy and to ensure no displacement during processing).

[0100] The clamping stroke H = 40mm (adapting to the initial gap between the housing positioning reference and the pressure plate).

[0101] Oil cut-off continuous pressing time T≥1800h (meets the continuous operation requirements of batch processing on the production line).

[0102] The contact area between the pressure plate and the workpiece is ≥400mm² (using polyurethane material for the pressure plate to prevent indentations on the aluminum alloy surface). S2: Determine the assembly relationship of the self-locking components:

[0103] Push-pull locking rod - push rod: adopts a 1:12 taper tapered fit, the tapered end of the push-pull locking rod is inserted into the tapered groove of the push rod to a depth of 20mm, and the gap is controlled at 0.03mm;

[0104] Wedge locking pin - wedge locking block: Two wedge locking pins are evenly distributed circumferentially, extending axially along the push-pull locking rod, and forming a surface contact engagement with the wedge groove on the inner wall of the wedge locking block;

[0105] Connecting block: It adopts a bolt connection method, with one end fixed to the cylinder housing (material HT300) and the other end rigidly connected to the wedge-shaped locking block (40Cr steel) to ensure no relative displacement.

[0106] S3: Component Selection:

[0107] S4: Key Parameter Calculation

[0108] Calculation of wedge locking pin and wedge groove dimensions:

[0109] The effective locking length L1 = H / sinβ = 40mm / sin6° ≈ 381mm, so we take 385mm.

[0110] Wedge groove depth = 385mm + 7mm (insertion allowance) = 392mm;

[0111] The wedge groove width = 8mm + 0.04mm (gap) = 8.04mm, which meets the 0.02-0.05mm gap requirement.

[0112] Push-pull locking rod tapered fit strength check:

[0113] Shear force Q = F × sinβ = 8000 N × sin6° ≈ 837 N;

[0114] Shear stress τ = 4Q / (πd²) = 4 × 837 / (π × 10²) ≈ 10.6 MPa ≤ [τ] = 180 MPa (allowable shear stress of 40Cr steel);

[0115] The projected area of ​​the conical mating surface A = π × (d / 2)² = π × 5² ≈ 78.5 mm²;

[0116] The compressive stress σ = F / A = 8000 / 78.5 ≈ 102 MPa ≤ [σ] = 300 MPa (allowable compressive stress for 40Cr steel), and the strength meets the standard.

[0117] Connector block strength calculation:

[0118] The connecting block withstands a pressure F1 = F × cosβ = 8000 × cos6° ≈ 7952 N;

[0119] The thickness of the connecting block is t=F1 / (b×[σ_b])=7952 / (40×80)=2.48mm (HT300 allowable bending stress[σ_b]=80MPa), and t=12mm is taken (≥10mm, to meet the rigidity requirements).

[0120] Hydraulic pressure matching calculation:

[0121] The force-bearing area of ​​the hydraulic cylinder piston rod is S = πD² / 4 = π × 38² / 4 ≈ 1134 mm²;

[0122] The hydraulic pressure P=F / S=8000 / 1134≈7.05MPa. A relief valve with a set pressure of 8MPa should be selected to avoid overload.

[0123] S5: Prototype Manufacturing and Testing

[0124] Prototype assembly: Process the parts according to the above parameters, and complete the assembly of the hydraulic cylinder, self-locking component, and clamping actuator component, ensuring that the wedge locking pin is smoothly inserted without jamming;

[0125] Performance test: Oil cut-off continuous compression: After oil cut-off, continuous compression was maintained for 1920 hours, and the compression force remained at 7.8kN, satisfying the requirement that the pressure remains unchanged for T≥1800h;

[0126] Reverse impact resistance: Withstands a reverse impact force of 20kN without displacement of the gearbox housing, with a machining requirement of less than 0.005mm;

[0127] S6: Optimization Iteration

[0128] During the experiment, it was found that the wedge locking pin had slight wear after the impact test. The hardness of the wedge locking pin was adjusted from HRC40-45 to HRC45-50, and the surface roughness of the wedge groove was optimized from Ra1.6μm to Ra0.8μm to reduce friction and wear. After optimization, a second test showed that the wear was reduced by 60%, and the locking stability was further improved.

[0129] This invention achieves the oil cut-off and pressure-maintaining function of a hydraulic clamp through a mechanical self-locking structure of "wedge locking pin-push rod-push-pull locking rod," fundamentally solving the problem of high energy consumption during continuous oil supply in traditional equipment. Simultaneously, the provided design method clarifies component selection and parameter calculation processes, ensuring the structure is feasible and its performance verifiable. It is not only suitable for automated processing fixtures but can also be extended to scenarios requiring energy-saving clamping, such as agricultural machinery and construction machinery, demonstrating significant practical and economic value.

[0130] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These are all equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of these fall within the protection scope of the present invention.

Claims

1. A hydraulic clamping device with a mechanical self-locking structure, comprising: A hydraulic cylinder and a hydraulic cylinder piston rod slidably disposed within the hydraulic cylinder, characterized in that a self-locking assembly is provided on the hydraulic cylinder, the self-locking assembly including a wedge-shaped locking pin, a push rod, a push-pull locking rod, and a wedge-shaped locking block, one end of the push-pull locking rod being axially connected to the push rod, and the other end being axially connected to the hydraulic cylinder piston rod; The wedge-shaped locking pin is circumferentially disposed on the outer wall of the push-pull locking rod, the wedge-shaped locking block is sleeved on the outside of the push rod, the inner wall of the wedge-shaped locking block is provided with a wedge-shaped groove, the wedge groove is adapted to the shape of the wedge-shaped locking pin, the wedge-shaped locking pin extends from the push-pull locking rod to the wedge-shaped locking block, and the wedge-shaped locking pin can be inserted into the wedge groove; When the oil cylinder is cut off, the wedge-shaped locking pin and the wedge-shaped locking block form a rigid engagement, and the push-pull locking rod maintains the relative position of the push rod and the piston rod of the oil cylinder, thereby maintaining the overall locked state and achieving continuous pressing without continuous oil supply; The push-pull locking rod has a tapered structure, and the tapered structure gradually increases in size along the direction of travel. The wedge-shaped locking pin has two contact surfaces, a first contact surface and a second contact surface. When the push-pull locking rod moves, it first contacts the first contact surface to form a preliminary locking mechanism. As it continues to move forward and come into contact with the second contact surface, the larger the contact area with the second contact surface, the stronger the locking force formed. When the push-pull locking rod contacts the first and second contact surfaces, the wedge-shaped locking pin moves along the wedge-shaped groove; The wedge angle of the wedge locking pin is β, and β satisfies tanβ≤μ; A connecting block is provided between the hydraulic cylinder and the self-locking assembly. The connecting block is fixed between the wedge-shaped locking block and the hydraulic cylinder housing, thereby achieving a rigid connection between the hydraulic cylinder and the self-locking assembly.

2. A hydraulic clamping device with a mechanical self-locking structure according to claim 1, characterized in that: The push-pull locking rod is provided with a step, which is located at the end of the conical structure.

3. A hydraulic clamping device with a mechanical self-locking structure according to claim 1, characterized in that: The free end of the self-locking component is connected to a clamping actuation component, which includes a clamping arm and a pressure plate. One end of the clamping arm is connected to the outer wall of the wedge-shaped locking block, and the other end is detachably connected to the pressure plate.

4. A hydraulic clamping device with a mechanical self-locking structure according to claim 1, characterized in that: The push rod and the push-pull locking rod are connected at a tapered groove. The diameter d of the push-pull locking rod is 8-15mm, and the taper of the tapered end is 1:10-1:

15. The taper of the tapered groove is consistent with the tapered end of the push-pull locking rod to ensure the stability and shear strength of the two when they are inserted together.

5. A design method for a hydraulic clamping device with a mechanical self-locking structure, characterized in that: The design of a hydraulic clamping device with a mechanical self-locking structure as described in any one of claims 1-4 includes the following steps: S1: Requirements Analysis: Determine the target clamping force F, clamping stroke H, and continuous clamping time T after oil cut-off, and clarify the contact area requirements between the pressure plate and the workpiece; S2: Determine the assembly relationship of the self-locking components: the tapered fit of the push-pull locking rod and the push rod, the wedge-shaped locking pin and the wedge-shaped locking block, and the connecting block connects the hydraulic cylinder and the self-locking components; S3: Component selection: Select the cylinder piston rod diameter D, wedge locking pin material, push-pull locking rod diameter d and material, wedge locking block material, connecting block material, and pressure plate material according to requirements; S4: Calculation of key parameters: Calculation of wedge locking pin and wedge groove dimensions, strength verification of tapered fit of push-pull locking rod, strength of connecting block and hydraulic pressure matching; S5: Prototype Manufacturing and Testing: Manufacturing a prototype, testing the continuous pressing time after oil cut-off, reverse impact resistance performance, and energy consumption data to verify whether it meets the requirements; S6: Optimization and Iteration: Adjust the wedge angle β, the taper of the push-pull locking rod tapered end, and the thickness of the connecting block parameters according to the test results until the performance meets the standards.

6. The design method of a hydraulic clamping device with a mechanical self-locking structure according to claim 5, characterized in that: The calculation of key parameters in step S4 includes: Calculation of wedge locking pin and wedge groove dimensions: The effective locking length L1 of the wedge locking pin is L1 = H / sinβ. The depth of the wedge groove is 5-10mm greater than the effective locking length of the wedge locking pin. The width of the wedge groove is matched with the width of the wedge locking pin to meet the clearance requirements. Strength check of the tapered fit of the push-pull locking rod: shear force Q=F×sinβ, shear stress τ=4Q / (πd²), τ≤[τ]; at the same time, check the compressive stress of the tapered mating surface σ=F / A, σ≤[σ]; Calculation of connecting block strength: The pressure F1 borne by the connecting block is F×cosβ, the thickness of the connecting block is t=F1 / (b×[σ_b]), and t≥10mm; Hydraulic pressure matching calculation: Hydraulic pressure P = F / S.

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