An inner support type fixing jig for rough machining of a piston and a fixing method

Abstract

The present application relates to the technical field of piston processing, and discloses an inner support type fixing clamp and fixing method for rough machining of a piston, which comprises a base, a radial support opening assembly, the radial support opening assembly comprising a middle block and an outer support jaw, and an axial support assembly, the axial support assembly comprising a stopper which is synchronous with the middle block to ascend to the highest point and then stop, the stopper being in contact with the pin seat inclined surface of the piston to be machined when moving to the highest point, the middle block continuing to ascend until the outer support jaw abuts against the inner wall of the piston to be machined. The piston to be machined is supported by the base, constrained by the stopper and the outer support jaw, and fixed relative to the base, so that the clamping efficiency is ensured; when the stopper reaches the highest point, the middle block continues to ascend to push the outer support jaw against the piston to be machined, so that the force applied by the outer support jaw to the inner wall of the piston to be machined is related to the ascending distance of the middle block, the work of the gland on the piston to be machined is avoided, and the risk of cracking of the skirt is eliminated.

Description

Technical Field

[0001] This invention relates to the field of piston machining technology, and specifically to an internal support type fixing fixture and fixing method for rough machining of pistons. Background Technology

[0002] In the roughing stage of piston casting, such as turning the piston outer diameter and drilling the oil return hole, the piston's inner cavity is used as a positioning reference for clamping. Currently, the industry commonly uses an internal support type clamp consisting of a stop block, a medium block forming an inclined surface, a double-ear opening mechanism, and a central spring linkage. This device uses a hydraulic cylinder to push the medium block and stop block upwards. The stop block first contacts the piston's inner top surface and pushes the piston upwards, suspending its inner top surface. Simultaneously, the inclined surface on the medium block continuously drives the outer support claws on both sides to extend outwards, causing the outer support claws to contact the inclined surface of the piston's inner wall and generate radial expansion force. Finally, the pressure cap presses the piston axially down to the base limiting surface, thus completing the rapid positioning and fixing of the workpiece. This device has become a standardized application on roughing production lines.

[0003] However, the aforementioned conventional internal support fixture has revealed an inherent process defect due to the timing of its structural actions during long-term use. Specifically, before the pressure cap performs its downward action, the piston is lifted by the stop block and the intermediate block and is in an axially suspended state. At this time, the outer support claw has already contacted and clamped against the inclined surface of the piston's inner wall. When the pressure cap begins to press down and pushes the piston as a whole towards the base limiting surface, the inclined surface of the piston's inner wall begins to displace downward. However, the outer support claw fails to descend synchronously with the piston due to the fixed intermediate block, causing the outer support claw to slide along the inclined surface of the piston's inner wall. This generates a strong wedging effect and stress concentration in the contact area between the outer support claw and the interior. Since the piston blank in the rough machining stage is a casting, the material strength and plasticity of its skirt inner wall inclined surface are limited. The additional radial expansion force caused by the clamping action can easily exceed the material's bearing limit, resulting in cracks in the inner wall of the piston skirt along the inclined surface direction. In severe cases, it can even directly crack the skirt, causing the workpiece to be scrapped.

[0004] It is evident that there is kinematic interference between the axial clamping action of the gland and the radial opening action of the outer support claw in the existing device. This structural contradiction of "clamping leading to cracking" increases the scrap rate in the roughing process and restricts the further improvement of production yield. Therefore, how to ensure clamping efficiency while eliminating the mechanical interference of the gland's pressing action on the radial opening state of the outer support claw and eliminating the risk of piston skirt cracking has become an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the challenge of ensuring clamping efficiency while eliminating the mechanical interference caused by the downward pressing action of the pressure cap on the radially expanded external support claws, thus preventing the risk of piston skirt cracking, this invention provides an internal support type fixing fixture and fixing method for rough machining of pistons. The specific technical solution is as follows: An internal support type fixing fixture for rough machining of pistons includes: a base, on which the piston to be machined is placed; a radial expansion assembly disposed on the base, the radial expansion assembly including a medium block that can be raised and lowered relative to the base and an outer support claw driven by the medium block to achieve radial expansion, so as to form a radial limit on the piston to be machined; and an axial support assembly disposed on the base, the axial support assembly including a stop block that rises and falls synchronously with the medium block to the highest point and then stops, when the stop block moves to the highest point, it contacts the inclined surface of the pin seat of the piston to be machined, the medium block continues to rise until the outer support claw abuts against the inner wall of the piston to be machined, so as to form a horizontal unidirectional limit on the piston to be machined.

[0006] Furthermore, the base includes a bolt mounting plate at the top and several limiting bolts passing through the bolt mounting plate. The limiting bolts can adjust the height relative to the bolt mounting plate to adjust the height of the highest point.

[0007] Furthermore, the left and right sides of the medium block form symmetrical first inclined planes, which are inclined planes that expand radially outward from top to bottom; The outer support claws are arranged in pairs symmetrically, and each outer support claw has a second inclined surface that cooperates with the first inclined surface; As the middle block rises, the first inclined surface pushes against the second inclined surface, forcing the outer support claws to expand radially outward in sync.

[0008] Preferably, the outer support claw is rotatably connected to the base, and the second inclined surface is a curved surface tangent to the first inclined surface; When the middle block rises, the first inclined surface pushes against the curved surface, forcing the outer support claws to rotate outwards synchronously; When the middle block moves to its highest position, the outer support claws abut against the inner wall of the piston to be processed, thereby forming a radial limit on the piston to be processed.

[0009] Preferably, the second inclined surface is composed of an arcuate surface tangent to the first inclined surface and a straight surface parallel to the first inclined surface; When the middle block rises, the first inclined surface pushes against the arc-shaped surface, forcing the outer support claws to rotate outwards synchronously; When the middle block moves to the highest position, the flat surface coincides with the first inclined surface and the outer support claw abuts against the inner wall of the piston to be processed, so as to form a radial limit on the piston to be processed.

[0010] Preferably, the radial expansion assembly further includes a lifting member disposed on the base, the lifting member forming an axial active lifting structure, the stroke of the axial active lifting structure being adjustable to drive the medium block to axially lift and lower.

[0011] Preferably, the axial support assembly further includes a central spring disposed between the intermediate block and the stop block; When the stop block moves to its highest point, the medium block continues to rise and compresses the central spring, causing the outer support claw to expand radially outward.

[0012] Preferably, the axial support assembly further includes: The upper part of the limiting plate and the medium block forms a lifting area with an open end. The open end of the lifting area is connected to the limiting plate to form a closed area that allows the block to rise and fall relative to each other. And an independently lifting pressure cap, which descends relative to the top of the base to form an axial limit on the piston to be processed.

[0013] Preferably, the two sides of the stop block form a relatively inclined third slope, which cooperates with the inclined surface of the pin seat of the piston to be processed to form a horizontal unidirectional limit on the piston to be processed.

[0014] A fixing method includes the following steps: placing the piston to be processed on the top of a base, so that the lower end face of the piston is in contact with the top of the base; driving the intermediate block to rise, so that the stop block and the intermediate block rise synchronously, while the outer support claw expands radially as the intermediate block rises; when the stop block moves to the hard limiting structure at the highest point, the third inclined surface of the stop block contacts the inclined surface of the pin seat of the piston to be processed, so as to form a horizontal unidirectional limiting of the piston to be processed, and the gap between the outer support claw and the piston to be processed is a, where a is greater than 0 mm; after the stop block stops, driving the intermediate block to rise, so that the intermediate block pushes the outer support claw to expand radially, so that the outer support claw abuts against the inner wall of the piston to be processed, i.e., a=0 mm; driving the pressure cap to press down, so that the top face of the piston to be processed is in contact with the pressure cap, thereby fixing the piston to be processed on the base.

[0015] As can be seen from the above technical solution, the present invention has the following beneficial effects: This invention supports the piston to be processed through a base, constrains the piston horizontally in one direction through a stop block, and further constrains the piston horizontally in one direction through a medium block and an outer support claw. The piston to be processed remains fixed relative to the base, ensuring clamping efficiency. When the stop block reaches its highest point, the medium block continues to rise to push the outer support claw against the inner wall of the piston to be processed. This ensures that the force applied by the outer support claw to the inner wall of the piston to be processed is related to the independent rising distance of the medium block, preventing the pressure cap from pressing down on the piston to do work and eliminating the risk of the piston skirt cracking. Attached Figure Description

[0016] Figure 1 This is an exploded structural diagram of the piston to be processed and Embodiment 1 of the present invention; Figure 2 This is a front sectional view of state one of the embodiments of the present invention; Figure 3 for Figure 2 Enlarged view of point A in the image; Figure 4 This is a front sectional view of state two of Embodiment 1 of the present invention; Figure 5 for Figure 4 Enlarged view of point B in the image; Figure 6 This is a side sectional view of state two of Embodiment 1 of the present invention; Figure 7 for Figure 6 Enlarged view of point C in the image; Figure 8 This is a front sectional view of state three of Embodiment 1 of the present invention; Figure 9 for Figure 8 Enlarged view of point D in the image.

[0017] In the diagram: 1. Base; 11. Limiting bolt; 12. Bolt mounting plate; 2. Radial expansion assembly; 21. Lifting component; 22. Medium block; 23. First inclined surface; 24. Outer support claw; 25. Second inclined surface; 3. Axial support assembly; 31. Stop block; 32. Third inclined surface; 33. Central spring; 34. Limiting plate; 35. Pressure cap; 4. Piston to be processed. Detailed Implementation

[0018] 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.

[0019] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0020] Example 1 like Figure 1 , Figure 2 and Figure 3As shown, state one is the state where the medium block 22 is in the initial position. This embodiment is an internal support type fixing fixture for rough machining of pistons, characterized in that it includes: a base 1, with the piston 4 to be machined placed at the top of the base 1; a radial expansion assembly 2 disposed on the base 1, the radial expansion assembly 2 including a medium block 22 that can be raised and lowered relative to the base 1 and an outer support claw 24 driven by the medium block 22 to achieve radial expansion, so as to form a radial limit on the piston 4 to be machined; and an axial support assembly 3 disposed on the base 1, the axial support assembly 3 including a stop block 31 that rises and falls synchronously with the medium block 22 to the highest point and then stops. When the stop block 31 moves to the highest point, it contacts the inclined surface of the pin seat of the piston 4 to be machined, and the medium block 22 continues to rise until the outer support claw 24 abuts against the inner wall of the piston 4 to be machined, so as to form a horizontal limit on the piston 4 to be machined.

[0021] Specifically, a bolt mounting plate 12 is installed at the top of the base 1, and three bolts with their tail ends facing upwards are installed on the bolt mounting plate 12. When the piston to be processed 4 is placed at the top of the base 1, its inner wall contacts the tail ends of the bolts, achieving a supporting effect. Secondly, the intermediate block 22 slides and rises relative to the base 1. The outer support claws 24 on both sides are rotatably connected to the top of the base 1 through pins. When the intermediate block 22 rises, it pushes the outer support claws 24 to rotate outwards, so that the distance between the outer support claws 24 on both sides and the inner wall of the piston to be processed 4 gradually decreases until it becomes zero, thereby achieving radial limiting of the piston to be processed 4. Secondly, the stop block 31 is placed on the upper part of the medium block 22. The stop block 31 and the medium block 22 form a slide rail with a concave and convex structure, so that the stop block 31 and the medium block 22 slide relative to each other along the fixed track. At the same time, as the medium block 22 rises, the stop block 31 rises synchronously until the stop block 31 rises to the highest point. At this time, the inclined side of the stop block 31 coincides with the inclined surface of the pin seat of the piston to be processed 4, forming a V-shaped limiting structure. Thus, the stop block 31 forms a horizontal unidirectional limiting structure with a vertical V-shaped limiting structure length for the piston to be processed 4. At the same time, it can also provide support for the piston to be processed 4, increase the axial limiting structure of the piston to be processed 4, and improve its stability.

[0022] When the stop block 31 rises to its highest point, it does not perform work on the inclined surface of the pin seat of the piston 4 to be processed via its tilted side. As the intermediate block 22 continues to rise, the relative positions of the stop block 31, the base 1, and the piston 4 to be processed remain unchanged until the outer support claw 24 contacts the inner wall of the piston 4 to be processed, thus achieving radial limiting of the piston 4 to be processed. Compared to the relative movement between the stop block 31 and the intermediate block 22 in the past, the position of the piston 4 to be processed remains unchanged from the top of the base 1. This avoids the piston 4 to be processed from descending relative to the outer support claw 24 during the subsequent pressing of the pressure cap 35, ensuring the clamping effect of the piston 4 to be processed while avoiding the risk of its skirt cracking.

[0023] like Figure 6 and Figure 7 As shown, the two sides of the stop block 31 form relatively inclined third slopes 32. The third slopes 32 cooperate with the inclined surface of the pin seat of the piston 4 to be processed, so as to form a horizontal unidirectional limit for the piston 4 to be processed. Specifically, the two sides of the stop block 31 have a symmetrical structure. The two sides of the third slopes 32 gradually expand outward from top to bottom to form a V-shaped structure. When the stop block 31 moves to the highest point, the third slopes 32 of the stop block 31 coincide with the inclined surface of the pin seat of the piston 4 to be processed, forming a horizontal unidirectional limit structure perpendicular to the length direction of the V-shaped structure, so as to fix the piston 4 to be processed.

[0024] Furthermore, the base 1 includes a bolt mounting plate 12 disposed at the top and a plurality of limiting bolts 11 passing through the bolt mounting plate 12. The limiting bolts 11 can adjust the height relative to the bolt mounting plate 12 to adjust the height of the highest point.

[0025] Specifically, the bolt mounting plate 12 is horizontally mounted on the top of the base 1, forming two through threaded holes for mounting the limit bolt 11. The limit bolt 11 is a headless screw, the top of which is embedded in the bolt mounting plate 12 to avoid affecting the piston 4 to be processed. Its bottom end protrudes from the bolt mounting plate 12, and its protrusion length can be adjusted by twisting relative to the bolt hole, thereby adjusting the distance of the highest point relative to the bolt mounting plate 12, and thus adjusting its height relative to the bottom of the base 1. When the stop block 31 moves to the highest point and contacts the bottom end of the limit bolt 11, the outer support claw 24 does not contact the inner wall of the piston 4 to be processed, so as to accommodate the manufacturing tolerance of the piston 4 to be processed, while allowing the intermediate block 22 to continue to rise for expansion.

[0026] like Figure 4 and Figure 5 As shown, state two is the state where the stop block 31 rises to the highest point. The left and right sides of the medium block 22 form a symmetrical first inclined surface 23. The first inclined surface 23 is an inclined surface that expands radially outward from top to bottom. The outer support claws 24 are arranged in pairs symmetrically. Each outer support claw 24 has a second inclined surface 25 that cooperates with the first inclined surface 23. When the medium block 22 rises, the first inclined surface 23 pushes the second inclined surface 25, forcing the outer support claws 24 to expand radially outward in sync.

[0027] Specifically, the intermediate block 22 moves up and down relative to the base 1, forming a first inclined surface 23 on both its left and right sides. The symmetrically arranged outer support claws 24 on the left and right sides are rotatably connected to the base 1, with the pivot point located directly above the first inclined surface 23. The side of the outer support claws 24 opposite to the first inclined surface 23 is the second inclined surface 25. When the intermediate block 22 moves upward, the first inclined surface 23 moves upward. The first inclined surface 23 first contacts the second inclined surface 25, and then pushes the second inclined surface 25 to deflect around the pivot point, causing the symmetrically arranged outer support claws 24 on the left and right sides to deflect outward at the same time. This causes the distance between the farthest points of the outer support claws 24 to gradually increase until the stop block 31 rises to the highest point under the push of the intermediate block 22. At this time, there may be a small gap between the outer support claws 24 and the inner wall of the piston 4 to be processed. The gap distance is 'a'. In this embodiment, the gap width 'a' is designed to be 0.1mm-0.15mm. When the diameter of the inner wall of the piston 4 to be processed after casting is smaller than the reference size, this gap can prevent the outer support claw 24 from contacting the piston 4 to be processed in advance. This advance contact means that the outer support claw 24 contacts the inner wall of the piston 4 to be processed before the stop block 31 reaches its highest point, thereby avoiding the risk of the skirt of the piston 4 to be processed cracking.

[0028] Furthermore, the outer support claw 24 is rotatably connected to the base 1, and the second inclined surface 25 is a curved surface tangent to the first inclined surface 23; when the middle block 22 rises, the first inclined surface 23 pushes the curved surface, forcing the outer support claw 24 to rotate outward synchronously; when the middle block 22 moves to the highest position, the outer support claw 24 abuts against the inner wall of the piston 4 to be processed, so as to form a radial limit on the piston 4 to be processed.

[0029] Specifically, in the first embodiment of the external support claw 24, the second inclined surface 25 is a continuously changing curved surface from bottom to top. When the first inclined surfaces 23 on the left and right sides respectively contact the second inclined surfaces 25 on the left and right sides, they are tangent to each other. The first inclined surface 23 continues to rise to push the second inclined surface 25 to deflect outward, so that the external support claws 24 on the left and right sides deflect outward synchronously until the external support claws 24 apply pressure to the inner wall of the piston 4 to be processed. This is reflected in the rising resistance of the middle block 22 reaching the set value, and the rising stops. This set value is set according to the actual production needs, so that the external support claws 24 can both apply outward force to the inner wall of the piston 4 to be processed and avoid excessive outward force that could crack the skirt of the piston 4 to be processed.

[0030] Furthermore, the second inclined surface 25 is composed of an arc-shaped surface tangent to the first inclined surface 23 and a straight surface parallel to the first inclined surface 23; when the middle block 22 rises, the first inclined surface 23 first pushes the arc-shaped surface, forcing the outer support claw 24 to rotate outward synchronously; when the middle block 22 moves to the highest position, the straight surface coincides with the first inclined surface 23 and the outer support claw 24 abuts against the inner wall of the piston 4 to be processed, so as to form a radial limit on the piston 4 to be processed.

[0031] Specifically, in a second embodiment of the external support claw 24: the lower half of the second inclined surface 25 is an arc-shaped surface, and its upper half is a straight surface. When the first inclined surfaces 23 on the left and right sides respectively contact the arc-shaped surfaces on the left and right sides, they are tangent to each other. The first inclined surfaces 23 continue to rise to push the arc-shaped surfaces to deflect outward, so that the external support claws 24 on the left and right sides deflect outward synchronously until the straight surface coincides with the first inclined surface 23. At this time, the external support claws 24 apply an outward force to the inner wall of the piston 4 to be processed, and the skirt of the piston 4 to be processed will not be torn. Among them, the starting position of the straight surface of the second inclined surface 25 is adjusted according to the experiment so that when the straight surface coincides with the first inclined surface 23, the external support claws 24 apply an outward force to the inner wall of the piston 4 to be processed, and the skirt of the piston 4 to be processed will not be torn.

[0032] Furthermore, the radially expanding assembly 2 also includes a lifting member 21 disposed on the base 1. The lifting member 21 forms an axially active lifting structure. The stroke of the axially active lifting structure is adjustable to drive the intermediate block 22 to rise and fall axially.

[0033] Specifically, the lifting component 21 can be a pneumatic cylinder, hydraulic cylinder, or electric cylinder, which is located inside the base 1, with its axial direction coinciding with that of the base 1. Its telescopic end is connected and fixed to the bottom end of the intermediate block 22, enabling it to push the intermediate block 22 and the stop block 31 upward. Secondly, the lifting component 21 has the same starting position, but its ending position is height-adjustable, allowing the ending position of the intermediate block 22 to be adjustable. This ensures that when the intermediate block 22 stops rising, the outer support claw 24 applies an outward force to the inner wall of the piston 4 to be processed, preventing the skirt of the piston 4 from cracking. Furthermore, a pressure sensor can be installed at the connection between the lifting component 21 and the intermediate block 22 to monitor the upward resistance of the intermediate block 22 in real time.

[0034] Furthermore, the axial support assembly 3 also includes a central spring 33 disposed between the intermediate block 22 and the stop block 31; when the stop block 31 moves to the highest point, the intermediate block 22 continues to rise and compress the central spring 33, so that the outer support claw 24 expands radially outward.

[0035] Specifically, the central spring 33 is a compression spring, with its top end embedded in the stop block 31 and its bottom end embedded in the intermediate block 22. It is always in a compressed state to maintain the distance between the intermediate block 22 and the stop block 31. Next, the intermediate block 22 pushes the stop block 31 to rise. When the stop block 31 rises to contact the bottom end of the limit bolt 11, the intermediate block 22 continues to rise to push the outer support claw 24 to continue to expand outward. At this time, the distance between the intermediate block 22 and the stop block 31 decreases, the central spring 33 is compressed, and it generates a downward elastic force on the intermediate block 22. This elastic force is part of the upward resistance at this time, until the outer support claw 24 applies a force to the inner wall of the piston 4 to be processed, forming a radial limit on the piston 4 to be processed, and the intermediate block 22 stops rising.

[0036] Furthermore, the axial support assembly 3 also includes: a limiting plate 34, the upper part of the medium block 22 forming a lifting area with an open end, the open end of the lifting area being connected to the limiting plate 34 to form a closed area that allows the stop block 31 to rise and fall relative to each other; and an independently lifting pressure cap 35, the pressure cap 35 descending relative to the top of the base 1 to form an axial limit on the piston 4 to be processed.

[0037] Specifically, the upper part of the medium block 22 forms a U-shaped area with an open end to create a lifting area for accommodating the stop block 31. When the stop block 31 is placed therein, the open end of the U-shaped area is closed using a limiting plate 34 and bolts to form a closed area. The inner side of the closed area and the side of the stop block 31 form a concave-convex slide rail to constrain the stop block 31 to move only up and down along the slide rail and only within the closed area. Secondly, the power source for the pressure cap 35 is a hydraulic cylinder or pneumatic cylinder, which moves downwards under external force until it presses against the piston 4 to be processed, thus forming an axial limiting structure for the piston 4 to be processed in conjunction with the top of the base 1.

[0038] Example 2 This embodiment is a fixing method based on Embodiment 1, which includes the following steps: like Figure 2 and Figure 3 As shown, state one is the state when the medium block 22 has not risen. Step one: Place the piston 4 to be processed on the top of the base 1, so that the lower end face of the piston is in contact with the top of the base 1. Specifically, the piston 4 to be processed has a cavity inside, which is fitted on the top of the base 1. The top surface of its internal cavity is in contact with the top end face of the base 1 to fix it and maintain its clamping position.

[0039] Step 2: Drive the intermediate block 22 to rise, causing the stop block 31 to rise synchronously with the intermediate block 22. At the same time, the outer support claw 24 expands radially as the intermediate block 22 rises. Specifically, the lifting component 21 drives the intermediate block 22 to rise relative to the base 1. The intermediate block 22 drives the stop block 31 to rise relative to the base 1 through the central spring 33. Simultaneously, the first inclined surface 23 of the intermediate block 22 first contacts the second inclined surface 25, and then pushes the second inclined surface 25 to deflect outward. The outer support claw 24 deflects outward relative to the base 1, causing the distance between the outer support claw 24 and the inner wall of the piston 4 to be processed to gradually decrease, as well as the distance between the stop block 31 and the bottom end of the limit bolt 11 to gradually decrease.

[0040] like Figure 4 and Figure 5As shown, state two is the state when the stop block 31 is in contact with the bottom end of the limit bolt 11. Step three: When the stop block 31 moves to the hard limit structure at the highest point, the stop block 31 contacts the inclined surface of the pin seat of the piston to be processed 4, so as to form a horizontal unidirectional limit on the piston to be processed 4, and the gap between the outer support claw 24 and the piston to be processed 4 is a, a is greater than 0mm. Specifically, when the stop block 31 contacts the bottom end of the limiting bolt 11, its third inclined surface 32 coincides with the inclined surface of the pin seat, forming a horizontal unidirectional limit on the piston 4 to be processed. This horizontal unidirectional limit is perpendicular to the length direction of the stop block 31, and this direction also intersects or is even perpendicular to the direction of the force applied by the outer support claw 24 to the piston 4 to be processed. Secondly, when the stop block 31 contacts the bottom end of the limiting bolt 11, there is a small gap a (such as 0.1mm) between the outer support claw 24 and the inner wall of the piston 4 to be processed, so as to avoid the outer support claw 24 contacting the inner wall of the piston 4 to be processed before the stop block 31 contacts the bottom end of the limiting bolt 11, which may lead to the risk of cracking of the skirt of the piston 4 to be processed.

[0041] like Figure 8 and Figure 9 As shown, state three is the state in which the outer support claw 24 is in contact with the piston 4 to be processed. Step four: After the stop block 31 stops, continue to drive the medium block 22 to rise. The medium block 22 pushes the outer support claw 24 to expand radially, so that the outer support claw 24 abuts against the inner wall of the piston 4 to be processed, i.e., a=0mm. Specifically, after the top of the stop block 31 contacts the bottom of the limiting bolt 11, the lifting member 21 continues to push the medium block 22 upward, the central spring 33 is compressed, and the outer support claw 24 continues to open outward until the outer support claw 24 applies force to the inner wall of the piston to be processed, with a small gap a=0mm. At this time, the outer support claws 24 on the left and right sides form a horizontal unidirectional limiting structure for the inner wall of the piston to be processed, and the third inclined surface 32 of the stop block 31 forms a horizontal unidirectional limiting structure for the inner wall of the piston to be processed. The two directions intersect, and at the same time, the top surface of the internal cavity of the piston to be processed 4 is in contact with the top end face of the base 1 to form a vertical unidirectional limiting structure, increasing the constraint of the piston to be processed 4.

[0042] Step 5: Press down the pressure cap 35 so that the top surface of the piston 4 to be processed is in contact with the pressure cap 35, thereby fixing the piston 4 to be processed onto the base 1. Specifically, the pressure cap 35 moves downward under the push of a cylinder or hydraulic cylinder until a force is applied to the top surface of the piston 4 to be processed, further reducing its degrees of freedom and achieving complete fixation of the piston 4 to be processed, preventing it from shaking during subsequent processing and affecting the processing quality.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0044] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. An internal support type fixing fixture for rough machining of pistons, characterized in that, include: A base (1) is provided, and the piston (4) to be processed is placed on the top of the base (1); A radial expansion assembly (2) disposed on the base (1) includes a central block (22) that is movable relative to the base (1) and an outer support claw (24) driven by the central block (22) to achieve radial expansion, thereby forming a radial limit on the piston (4) to be processed; and An axial support assembly (3) is provided on the base (1). The axial support assembly (3) includes a stop block (31) that moves synchronously with the intermediate block (22) to the highest point and then stops. When the stop block (31) moves to the highest point, it contacts the inclined surface of the pin seat of the piston to be processed (4). The intermediate block (22) continues to rise until the outer support claw (24) abuts against the inner wall of the piston to be processed (4) to form a horizontal limit on the piston to be processed (4).

2. The internal support type fixing clamp according to claim 1, characterized in that: The base (1) includes a bolt mounting plate (12) disposed at the top and a plurality of limiting bolts (11) passing through the bolt mounting plate (12). The limiting bolts (11) can adjust the height relative to the bolt mounting plate (12) to adjust the height of the highest point.

3. The internally braced fixture clamp of claim 1, wherein: The left and right sides of the medium block (22) form a symmetrical first inclined surface (23), which is an inclined surface that expands radially outward from top to bottom; The external support claws (24) are arranged in pairs symmetrically, and each external support claw (24) has a second inclined surface (25) that cooperates with the first inclined surface (23); When the medium block (22) rises, the first inclined surface (23) pushes against the second inclined surface (25), forcing the outer support claw (24) to expand radially outward in sync.

4. The internally braced fixture clamp of claim 3, wherein: The external support claw (24) is rotatably connected to the base (1), and the second inclined surface (25) is a curved surface tangent to the first inclined surface (23); When the medium block (22) rises, the first inclined surface (23) pushes against the curved surface, forcing the outer support claw (24) to rotate outward synchronously; When the medium block (22) moves to the highest position, the outer support claw (24) abuts against the inner wall of the piston (4) to be processed, so as to form a radial limit on the piston (4) to be processed.

5. The internal support type fixing clamp according to claim 4, characterized in that: The second inclined plane (25) is composed of an arcuate surface tangent to the first inclined plane (23) and a straight surface parallel to the first inclined plane (23); When the medium block (22) rises, the first inclined surface (23) first pushes the arc-shaped surface, forcing the outer support claw (24) to rotate outward synchronously; When the medium block (22) moves to the highest position, the flat surface coincides with the first inclined surface (23) and the outer support claw (24) abuts against the inner wall of the piston (4) to be processed, so as to form a radial limit on the piston (4) to be processed.

6. The internally braced fixture clamp of claim 1, wherein: The radial expansion assembly (2) also includes a lifting member (21) disposed on the base (1), the lifting member (21) forming an axial active lifting structure, the stroke of the axial active lifting structure being adjustable to drive the medium block (22) to rise and fall axially.

7. The internally braced fixture clamp of claim 1, wherein: The axial support assembly (3) further includes a central spring (33) disposed between the intermediate block (22) and the stop block (31); When the stop block (31) moves to the highest point, the medium block (22) continues to rise and compress the central spring (33) so that the outer support claw (24) expands radially outward.

8. The internally braced fixture clamp of claim 1, wherein: The axial support assembly (3) also includes: The upper part of the medium block (22) forms a lifting area with an open end, and the open end of the lifting area is connected to the limiting plate (34) to form a closed area that allows the stop block (31) to rise and fall relative to each other. And an independently lifting pressure cap (35), which descends relative to the top of the base (1) to axially limit the piston (4) to be processed.

9. The internally braced fixture clamp of claim 1, wherein: The two sides of the stop (31) form a relatively inclined third slope (32), which cooperates with the pin seat slope of the piston (4) to form the horizontal unidirectional limit on the piston (4).

10. A method of securing according to any one of claims 1 to 9, characterised in that, Includes the following steps: S1: Place the piston (4) to be processed on the top of the base (1) so that the lower end face of the piston is in contact with the top of the base (1); S2: Drive the medium block (22) to rise, so that the stop block (31) and the medium block (22) rise synchronously, and at the same time the outer support claw (24) expands radially as the medium block (22) rises; S3: When the stop block (31) moves to the hard limit structure at the highest point, the third inclined surface (32) of the stop block (31) contacts the pin seat inclined surface of the piston to be processed (4) to form a horizontal unidirectional limit on the piston to be processed (4), and the gap between the outer support claw (24) and the piston to be processed (4) is a, a is greater than 0mm. S4: After the stop block (31) stops, continue to drive the medium block (22) to rise, and push the outer support claw (24) to expand radially through the medium block (22), so that the outer support claw (24) abuts against the inner wall of the piston (4) to be processed, i.e., a=0mm; S5: Drive the pressure cap (35) down to make the top surface of the piston (4) to be processed fit with the pressure cap (35) so as to fix the piston (4) to be processed on the base (1).

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