A hydraulic clamping fixture for machining centers with stable clamping force

Abstract

This invention relates to the field of hydraulic clamping technology, and more particularly to a hydraulic clamping fixture for machining centers with stable clamping force. The technical solution includes a hydraulic cylinder comprising a cylinder body fixedly mounted on a base plate, a cover fixedly mounted on the cylinder body, and an output shaft slidably mounted inside the cylinder body and passing through the cover. A sealing assembly for sealing the output shaft is mounted on the cover. The sealing assembly includes a second sealing ring, and a receiving groove is provided inside the cover. The second sealing ring is located inside the receiving groove, and a negative pressure state exists between the second sealing ring and the receiving groove. This invention, through a negative pressure receiving groove design, a gravity-sensing amplification mechanism for hydraulic oil leakage, and a high-pressure gas triggering mechanism, achieves automatic, non-interventional activation of the backup seal after the main seal fails, greatly improving the reliability of the sealing system and the long-term stability of the clamping force. Simultaneously, the backup seal does not contact the output shaft in standby mode, fundamentally avoiding ineffective wear.

Description

Technical Field

[0001] This invention relates to the field of hydraulic clamping technology, and in particular to a hydraulic clamping fixture for machining centers with stable clamping force. Background Technology

[0002] As a core piece of equipment in modern high-efficiency CNC machining, the performance of hydraulic clamping fixtures in machining centers hinges on their ability to provide continuous, stable, and reliable clamping force. The key to this lies in the design and manufacture of their actuators—hydraulic cylinders and their internal precision sealing systems. A hydraulic cylinder is essentially a linear actuator that converts the fluid pressure energy provided by a hydraulic station into mechanical clamping force. Its core is a sealed pressure chamber containing a piston, piston rod, and a series of precision seals.

[0003] A complex seal is installed at the piston rod outlet. Generally, a double seal is used to improve the sealing strength, which can effectively prevent external chips and coolant from entering. However, the sealing ring closest to the hydraulic oil often plays a priority role in sealing. The upper valve sealing ring often does not play a sealing role before the lower sealing ring fails, but relative sliding between it and the piston rod will still occur, resulting in wear. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the background art by proposing a hydraulic clamping fixture for machining centers with stable clamping force that activates the upper seal after the lower seal fails.

[0005] The technical solution of the present invention: A hydraulic clamping fixture for a machining center with stable clamping force, comprising a base plate, and further comprising:

[0006] Multiple clamping systems are mounted on a substrate, each clamping system including clamps and hydraulic cylinders for driving the clamps to move.

[0007] The hydraulic cylinder includes a cylinder body fixedly mounted on a base plate, a cover fixedly mounted on the cylinder body, and an output shaft slidably mounted inside the cylinder body and passing through the cover. A sealing assembly for sealing the output shaft is mounted on the cover. The sealing assembly includes a first sealing ring fixedly mounted inside the cover and a second sealing ring located above the first sealing ring. The cover has a receiving groove with an outer diameter larger than the outer diameter of the second sealing ring. The second sealing ring is located inside the receiving groove, and the second sealing ring and the receiving groove are under negative pressure.

[0008] The sealing assembly includes two connecting pipes, one of which has a plug slidably installed inside and is connected to a pressurization module, the pressurization module containing high-pressure gas;

[0009] The release component and the limiting component are installed inside the cover. The release component applies a pulling force to the plug to disengage from the connecting pipe. The limiting component includes an intermediate groove between the first sealing ring and the second sealing ring and a limiting plate that prevents the release component from releasing the pulling force. The limiting component amplifies the gravity of the hydraulic oil in the intermediate groove and drives the limiting plate to disengage from the release component.

[0010] Optionally, the upper and lower sides of the cylinder body are provided with connection holes, the connection holes are connected to a hydraulic power source, a third sealing ring is fixedly installed on the output shaft, and multiple fourth sealing rings are fixedly installed between the cover and the cylinder body.

[0011] Optionally, the connecting pipe connected to the plug extends to the outside of the cap and is fixedly installed with a first valve.

[0012] Optionally, the release assembly includes a pull rod fixedly mounted on the plug and an elastic element fixedly mounted between the plug and the cap, the pull rod extending into the interior of the intermediate groove.

[0013] Optionally, the limiting plate is located inside the intermediate groove and slidably connected to the cover. The limiting component also includes a groove inside the intermediate groove, a pressure ring slidably installed inside the groove, and a transmission component installed between the pressure ring and the limiting plate. The transmission component amplifies the pressure borne by the pressure ring and drives the limiting plate to move.

[0014] Optionally, the transmission component includes a slider slidably mounted on the pressure ring and a lever rotatably mounted on the slider. One end of the lever near the limiting plate is rotatably connected to the inner wall of the intermediate groove through a support plate. One end of the lever is slidably mounted with a sliding rod, which is rotatably connected to the limiting plate.

[0015] Optionally, the pressurization module includes an air chamber disposed inside the cover and connected to one of the connecting pipes. A sealing plate is slidably and sealingly connected inside the air chamber. A protrusion is fixedly installed on the sealing plate. The cover is provided with a hole for the protrusion to pass through. The air chamber is connected to the end face of the cover through a delivery pipe and a second valve is fixedly installed thereon.

[0016] Optionally, the cover is provided with a plurality of fifth sealing rings, the fifth sealing rings being located above the second sealing rings.

[0017] Optionally, the fixture includes a support base fixedly mounted on the substrate, a clamping block slidably mounted on the support base, and a driving block, wherein the driving block and the clamping block are slidably connected and the sliding surface is inclined.

[0018] Optionally, the support base is provided with multiple positioning holes and positioning pins, and a connecting shaft is fixedly installed on the output shaft. The connecting shaft is fixedly connected to the drive block through a connector.

[0019] In summary, this application includes at least one of the following beneficial technical effects:

[0020] This invention employs a negative pressure receiving groove structure, ensuring that the second sealing ring is in an outward-expanding state and does not contact the output shaft when not in operation. When the main seal leaks, hydraulic oil seeps into the intermediate groove, driving the limit plate to release the constraint on the release component via a gravity-sensing amplification mechanism. This triggers high-pressure gas to rapidly fill the receiving groove, changing it from negative pressure to positive pressure. This forces the second sealing ring to contract and grip the output shaft, automatically activating the backup seal. This mechanism ensures that the system maintains an effective seal even when the main seal fails, greatly improving the reliability of the sealing system and the long-term stability of the clamping force. In standby mode, the backup seal remains in a non-contact state with the output shaft due to the negative pressure, fundamentally avoiding unnecessary friction and wear, significantly extending the service life of the seals, and reducing maintenance frequency and costs. Attached Figure Description

[0021] Figure 1 Schematic diagram of the hydraulic fixture for machining center Figure 1 ;

[0022] Figure 2 Schematic diagram of the hydraulic fixture for machining center Figure 2 ;

[0023] Figure 3 Schematic diagram of the clamping system Figure 1 ;

[0024] Figure 4 Schematic diagram of the clamping system Figure 2 ;

[0025] Figure 5 Schematic diagram of the clamping system Figure 3 ;

[0026] Figure 6 for Figure 5 A magnified view of a section at point A in the middle;

[0027] Figure 7 for Figure 5 A magnified view of a section at point B in the middle;

[0028] Figure 8 for Figure 5 A magnified view of a section at point C;

[0029] Figure 9 for Figure 7 A magnified view of a section at point D.

[0030] Figure label:

[0031] 1. Substrate;

[0032] 2. Fixture system;

[0033] 21. Fixture; 211. Support base; 212. Clamping block; 213. Drive block; 214. Positioning hole; 215. Positioning pin; 216. Connecting shaft; 217. Connecting component;

[0034] 22. Hydraulic cylinder; 221. Cylinder body; 222. Connecting hole; 223. Cover; 224. Output shaft; 225. Third sealing ring; 226. Fourth sealing ring;

[0035] 23. Sealing assembly; 231. First sealing ring; 232. Second sealing ring; 233. Receiving groove; 234. Connecting pipe; 235. First valve; 236. Plug;

[0036] 24. Release assembly; 241. Pull rod; 242. Elastic element;

[0037] 25. Limiting component; 251. Limiting plate; 252. Groove; 253. Pressure ring; 254. Slider; 255. Lever; 256. Support plate; 257. Slide rod; 258. Intermediate groove;

[0038] 26. Boosting module; 261. Air chamber; 262. Sealing plate; 263. Protrusion block; 264. Delivery pipe; 265. Second valve;

[0039] 27. Fifth sealing ring. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0041] like Figures 1 to 4 As shown, the present invention proposes a hydraulic clamping fixture for a machining center with stable clamping force, including a base plate 1 and multiple clamping systems 2 mounted on the base plate 1, which can clamp and fix multiple workpieces simultaneously. The clamping system 2 includes a clamp 21 and a hydraulic cylinder 22 for driving the clamp 21 to move. The clamp 21 clamps the workpiece and provides power to the clamp 21 through the hydraulic cylinder 22.

[0042] Furthermore, the fixture 21 includes a support base 211 fixedly mounted on the base plate 1, a clamping block 212 slidably mounted on the support base 211, and a drive block 213. The drive block 213 and the clamping block 212 are slidably connected, and the sliding surface is inclined, so that the lifting and lowering of the drive block 213 can push the clamping block 212 to move horizontally, thereby clamping and fixing the workpiece with the clamping block 212.

[0043] The support base 211 is provided with multiple positioning holes 214 and positioning pins 215. The positioning holes 214 and positioning pins 215 are set based on the shape and structure of the workpiece, which can accurately clamp and position the workpiece.

[0044] As one implementation method, such as Figures 5 to 8 As shown, the hydraulic cylinder 22 includes a cylinder body 221 fixedly mounted on the base plate 1, a cover 223 fixedly mounted on the cylinder body 221, and an output shaft 224 slidably mounted inside the cylinder body 221 and passing through the cover 223. Under the action of hydraulic pressure, the output shaft 224 can be pushed to move up and down. A connecting shaft 216 is fixedly mounted on the output shaft 224. The connecting shaft 216 is fixedly connected to the drive block 213 through a connector 217, thereby causing the drive block 213 to move as the output shaft 224 moves.

[0045] The cylinder body 221 has connection holes 222 on both its upper and lower sides, which are connected to a hydraulic power source. By applying pressure to the output shaft 224 in different directions using the hydraulic power source, the output shaft 224 can be moved up and down. This is existing technology and will not be elaborated upon here. A third sealing ring 225 is fixedly installed on the output shaft 224, which divides the cylinder body 221 into two parts and prevents the hydraulic oil in the two parts from seeping into each other, ensuring the stability of the hydraulic pressure inside the cylinder body 221. Multiple fourth sealing rings 226 are fixedly installed between the cover 223 and the cylinder body 221 to prevent hydraulic oil from leaking through the connection between the cover 223 and the cylinder body 221, effectively achieving a sealing effect.

[0046] As one implementation method, such as Figure 6 and Figure 7 As shown, a sealing assembly 23 for sealing the output shaft 224 is installed on the cover 223. The sealing assembly 23 includes a first sealing ring 231 fixedly installed inside the cover 223 and a second sealing ring 232 located above the first sealing ring 231. The first sealing ring 231 and the second sealing ring 232 form a double seal, which can effectively improve the sealing performance. When the first seal fails, the hydraulic oil can be isolated through the second seal. The cover 223 has a receiving groove 233 with an outer diameter larger than the outer diameter of the second sealing ring 232. The second sealing ring 232 is located inside the receiving groove 233, and the second sealing ring 232 and the receiving groove 233 are in a negative pressure state. This causes the second sealing ring 232 to expand outward under the action of the internal and external pressure difference, so that the inner ring of the second sealing ring 232 will not exert pressure on the output shaft 224, thereby preventing wear of the second sealing ring 232 before it is used and effectively improving its service life.

[0047] Furthermore, the sealing assembly 23 includes two connecting pipes 234. One of the connecting pipes 234 has a plug 236 slidably installed inside and is connected to a pressurization module 26. The pressurization module 26 contains high-pressure gas. When the high-pressure gas inside the pressurization module 26 is released, it will apply air pressure to the inside of the receiving groove 233. At this time, the air pressure inside the receiving groove 233 will change from negative pressure to positive pressure, which will apply pressure to the second sealing ring 232, causing the second sealing ring 232 to contact and pressurize the output shaft 224, thereby sealing the output shaft 224. The connecting pipe 234 connected to the plug 236 extends to the outside of the cover 223 and is fixedly installed with a first valve 235. The first valve 235 can be used to evacuate the inside of the receiving groove 233, so that the inside of the receiving groove 233 is in a negative pressure state. After the evacuation is completed, the first valve 235 is closed to maintain the negative pressure state inside the receiving groove 233, so that the second sealing ring 232 is always in an outward expansion state.

[0048] As one implementation method, such as Figures 5 to 9 As shown, the hydraulic clamp of the machining center also includes a release component 24 and a limiting component 25 installed in the cover 223. The release component 24 applies a pulling force to the plug 236 to disengage from the connecting pipe 234. When the pulling force is released, the plug 236 will disengage from the connecting pipe 234. At this time, the connecting pipe 234 will be connected to the pressurization module 26. The air pressure inside the pressurization module 26 can be released into the receiving groove 233 through the connecting pipe 234, so that the second sealing ring 232 applies pressure to the output shaft 224 under the action of its own elasticity and air pressure. The limiting component 25 includes an intermediate groove 258 provided between the first sealing ring 231 and the second sealing ring 232 and a limiting position that prevents the release component 24 from releasing the pulling force. When the sealing of the first sealing ring 231 initially fails, hydraulic oil will gradually penetrate through the first sealing ring 231 and enter the interior of the intermediate groove 258, causing hydraulic oil to gradually accumulate inside the intermediate groove 258. The pressure of the hydraulic oil entering the intermediate groove 258 will drop significantly, far less than the working pressure inside the main chamber, thus preventing the hydraulic oil from continuing to pass through the second sealing ring 232. The limiting component 25 amplifies the gravity of the hydraulic oil in the intermediate groove 258 and drives the limiting plate 251 to disengage from the release component 24. This causes the first sealing ring 231 to fail and activates the second sealing ring 232, achieving the function of autonomously detecting the sealing effect of the first sealing ring 231 and driving the second sealing ring 232 to perform sealing.

[0049] Furthermore, the release assembly 24 includes a pull rod 241 fixedly installed on the plug 236 and an elastic element 242 fixedly installed between the plug 236 and the cap 223. The pull rod 241 extends into the middle groove 258, and the elastic element 242 is a spring. The elastic element 242 applies a pulling force to the plug 236, allowing the plug 236 to detach from the connecting pipe 234. When the plug 236 moves, it will drive the pull rod 241 to move. When the first sealing ring 231 is not ineffective, the limiting plate 251 will limit the side of the pull rod 241, preventing the limiting plate 251 from moving, thereby preventing the elastic force of the elastic element 242 from being released and preventing the plug 236 from moving.

[0050] The limiting plate 251 is located inside the intermediate groove 258 and is slidably connected to the cover 223. The limiting component 25 also includes a groove 252 provided inside the intermediate groove 258, a pressure ring 253 slidably installed inside the groove 252, and a transmission component installed between the pressure ring 253 and the limiting plate 251. The transmission component amplifies the pressure borne by the pressure ring 253 and drives the limiting plate 251 to move. When the limiting plate 251 moves upward, the limiting plate 251 will not block the pull rod 241. At this time, the elastic force of the elastic element 242 can be released, thereby pulling the plug 236 to move.

[0051] Furthermore, the transmission components include a slider 254 slidably mounted on the pressure ring 253 and a lever 255 rotatably mounted on the slider 254. One end of the lever 255 near the limiting plate 251 is rotatably connected to the inner wall of the intermediate groove 258 through the support plate 256. A slide rod 257 is slidably mounted on one end of the lever 255 and is rotatably connected to the limiting plate 251. When hydraulic oil enters the interior of the intermediate groove 258, it will drive the pressure ring 253 to move down under the action of gravity, and through the action of the lever 255, it will drive the limiting plate 251 to rise, thereby releasing the elastic force of the elastic element 242.

[0052] like Figure 8As shown, in this embodiment, the pressurization module 26 includes an air chamber 261 disposed within the cover 223 and connected to one of the connecting pipes 234. A sealing plate 262 is slidably and sealingly connected within the air chamber 261. A protrusion 263 is fixedly installed on the sealing plate 262. The cover 223 has a hole for the protrusion 263 to pass through. The air chamber 261 is connected to the end face of the cover 223 through the delivery pipe 264 and a second valve 265 is fixedly installed thereon. By opening the second valve 265 and pressing the plug... When the connecting pipe 234 is blocked, high-pressure gas is filled into the air chamber 261 and the second valve 265 is closed. If the high-pressure gas is not released, the sealing plate 262 will be at the top. At this time, the protrusion 263 will be level with the cover 223. When the high-pressure gas inside the air chamber 261 is released after the first sealing ring 231 fails, the protrusion 263 will move down. The position of the protrusion 263 can be observed to determine whether the first sealing ring 231 has failed.

[0053] like Figure 6 As shown, in this embodiment, the cover 223 is provided with a plurality of fifth sealing rings 27. The fifth sealing rings 27 are located above the second sealing rings 232. The fifth sealing rings 27 can be used to remove impurities adhering to the output shaft 224.

[0054] In this embodiment, when the hydraulic power source supplies oil to the cylinder 221 through the connecting hole 222, the pressurized oil pushes the output shaft 224 to move, and then drives the drive block 213 to slide through the connecting shaft 216 and the connecting piece 217. The drive block 213 uses the inclined sliding surface to push the clamping block 212 to move horizontally, thereby clamping the workpiece. During normal operation, the first sealing ring 231 acts as the main seal to seal the output shaft 224. At this time, the receiving groove 233 is drawn into negative pressure through the first valve 235, causing the second sealing ring 232 to expand outward under the pressure difference, avoiding contact with the output shaft 224 and achieving zero-wear standby. If the first sealing ring 231 fails and leakage occurs, the hydraulic oil will seep into the intermediate groove 258 between the first sealing ring 231 and the second sealing ring 232. The leaked oil accumulates in the intermediate groove 258. The pressure ring 253 is pressed down by gravity. The force is amplified and the limiting plate 251 is lifted by the transmission component consisting of slider 254, lever 255 and slide rod 257. After the limiting plate 251 rises, it no longer blocks the pull rod 241 of the release component 24. The tension of the elastic element 242 that was originally constrained is released, pulling the plug 236 away from the connecting pipe 234. After the plug 236 falls off, the high-pressure gas pre-stored in the air chamber 261 of the pressurization module 26 enters the receiving groove 233 instantly through the connecting pipe 234, changing it from negative pressure to positive pressure. The positive pressure causes the second sealing ring 232 to contract, so that its inner ring tightly hugs the output shaft 224, thereby replacing the first sealing ring 231 to complete the sealing function, realizing automatic switching and backup of the seal. The protrusion 263 moves down with the sealing plate 262, providing a visual indication that the seal has failed.

[0055] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A machining center hydraulic clamp with stable clamping force, comprising a base plate, characterized in that, Also include: A plurality of sets of clamp systems mounted on the substrate, the clamp system comprising a clamp and a hydraulic cylinder driving the clamp to move; The hydraulic cylinder comprises a cylinder body fixedly mounted on the substrate, a cover fixedly mounted on the cylinder body, an output shaft slidingly mounted in the cylinder body and penetrating through the cover, a plugging assembly mounted on the cover for sealing the output shaft, the plugging assembly comprising a first plugging ring fixedly mounted in the cover and a second plugging ring located above the first plugging ring, the cover is provided with a containing groove with an outer diameter larger than that of the second plugging ring, the second plugging ring is located in the containing groove, and the second plugging ring and the containing groove are in a negative pressure state; The plugging assembly comprises two connecting pipes, one of which is slidingly mounted with a plug and connected with a pressure boosting module, the pressure boosting module is provided with high-pressure gas; A release assembly and a limiting assembly are mounted in the cover, the release assembly applies a pulling force to the plug to separate it from the connecting pipe, the limiting assembly comprises an intermediate groove between the first plugging ring and the second plugging ring and a limiting plate limiting the release of the release assembly, the limiting assembly amplifies the gravity of the hydraulic oil in the intermediate groove to drive the limiting plate to separate from the release assembly; The release assembly comprises a pull rod fixedly mounted on the plug and an elastic member fixedly mounted between the plug and the cover, the pull rod extends into the intermediate groove; The limiting plate is located in the intermediate groove and is slidingly connected with the cover, the limiting assembly further comprises a groove provided in the intermediate groove, a compression ring slidingly mounted in the groove, a transmission member mounted between the compression ring and the limiting plate, the transmission member amplifies the pressure borne by the compression ring and drives the limiting plate to move; The transmission member comprises a sliding block slidingly mounted on the compression ring and a lever rotatably mounted on the sliding block, one end of the lever near the limiting plate is rotatably connected with the inner wall of the intermediate groove through a support plate, one end of the lever is slidingly mounted with a slide rod, and the slide rod is rotatably connected with the limiting plate; The pressure boosting module comprises a gas cavity provided in the cover and communicating with one of the connecting pipes, the gas cavity slidingly and sealingly connects with a plugging plate, the plugging plate is fixedly mounted with a protruding block, the cover is provided with a hole for the protruding block to pass through, and the gas cavity is connected with the end face of the cover through a conveying pipe and is fixedly mounted with a second valve.

2. The hydraulic clamp of claim 1, wherein, Both sides of the cylinder body are provided with connecting holes connected with a hydraulic power source, the output shaft is fixedly mounted with a third sealing ring, and the cover and the cylinder body are fixedly mounted with a plurality of fourth sealing rings.

3. The hydraulic clamp of claim 2, wherein, The connecting pipe connected with the plug extends to the outside of the cover and is fixedly mounted with a first valve.

4. The hydraulic clamp of claim 3, wherein, The cover is provided with a plurality of fifth plugging rings located above the second plugging ring.

5. The hydraulic clamp of claim 4, wherein, The clamp comprises a support seat fixedly mounted on the substrate, a clamping block slidingly mounted on the support seat and a driving block, the driving block and the clamping block are slidingly connected, and the sliding surfaces are inclinedly arranged.

6. The hydraulic clamp of claim 5, wherein, The support seat is provided with a plurality of positioning holes and positioning pins, the output shaft is fixedly mounted with a connecting shaft, and the connecting shaft is fixedly connected with the driving block through a connecting member.

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