Fixture for piston with draft angle on side wall of inner cavity and implementation method

Abstract

The invention discloses a clamp for a piston with a draft angle on the side wall of an inner cavity and an implementation method, according to the characteristic of the draft angle on the side wall of the inner cavity of the piston, a clamp positioning point adopts the inclination with the same size as that of a corresponding positioning point of the piston, the inner side wall of the piston is tensioned by an inclined surface, and the effect of fixing the axis of the inner cavity of the piston is realized; the contour shape, size and inclination of the clamp positioning point are the same as those of the corresponding position of the side wall of the piston inner cavity, so that the shape of the positioning position on the clamp is completely matched with that of the piston inner cavity, and the positioning precision is effectively improved; under the condition that the actual size change of the side wall of an inner cavity of a piston blank is large, the clamp positioning element can automatically slide forwards under the action of spring force, and the inclined surface of the positioning element is always pushed to the draft inclined surface of the inner side wall of the piston, so that the inner side wall of the piston is always in a tensioned state, the size change of the blank is automatically adapted, and accurate and reliable positioning is ensured; therefore, the piston inner cavity wall thickness difference is controlled.

Description

Technical Field

[0001] The invention relates to the field of manufacturing aluminum pistons for internal combustion engines, and in particular to a clamp for a piston with a draft angle on an inner cavity side wall and a realization method thereof. Background Art

[0002] The aluminum piston of an internal combustion engine is generally inlaid with a high-nickel cast iron ring on the outer circle of the head. The cast iron ring is cast together with the aluminum body of the piston during the piston casting; an annular internal cooling oil channel is cast inside the head, as shown in the attached Figure 1 As shown in the figure, the inner edge of the piston pin hole is generally designed with machined chamfers, and the outer edge of the piston pin hole is designed with chamfers. When the piston wall thickness difference is large, it will cause the following problems: Figure 2 As shown in the figure, the inclination and position of the high nickel cast iron ring are difficult to meet the design requirements, causing the problem of uneven thickness of the cast iron material on the upper and lower sides of the cast iron ring groove. In severe cases, there will be no cast iron material to be processed on the lower side of the iron ring groove; it will also cause the annular internal cooling oil channel in the head to deviate beyond the tolerance, causing poor cooling of the piston head and causing perforation during engine operation; as shown in the attached figure Figure 3 As shown, it will also cause the inner and outer casting surfaces of the piston to deviate, leading to poor symmetry of the machined chamfers of the inner edge of the piston pin hole and the outer chamfers of the piston pin hole. The rest of the machined surfaces of the piston where they meet the casting surfaces will be deviated. The thickness of the inner top of the internal combustion engine piston has a direct impact on the weight of the finished piston, and should be strictly controlled during the machining process, otherwise the piston weight will be unqualified.

[0003] However, in actual production, the inner top surface of the piston is a non-machined casting surface, and the top surface of the piston is a machined surface. The piston top thickness is the distance from the inner top center casting surface to the machined top surface of the piston. Generally, the tolerance requirement is high. Due to the large casting tolerance, it is difficult to control the final top thickness tolerance, which ultimately affects the product weight. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned problems in the prior art and to provide a clamp and implementation method for a piston with a draft angle on the inner cavity side wall.

[0005] A clamp for a piston with a draft angle on the inner cavity side wall, comprising a positioning body, a positioning shaft push rod, a short shaft front positioning block, a short shaft rear positioning block, a long shaft floating block, a front push rod, a rear push rod, a positioning body transition plate, a spring mounting body, a long shaft floating spring top cover, a long shaft floating push rod, a long shaft floating spring, a spring top cover, a spring bottom cover, a spring, a long shaft floating block spring cover, a limit pin, a pull rod connecting rod, and a main shaft transition body;

[0006] The positioning body comprises a guide surface, a guide hole, a special-shaped mounting cavity, a front push rod guide hole, a rear push rod guide hole, a mounting hole, and a connection stop;

[0007] The positioning shaft push rod is arranged on the positioning body through the guide hole, and the short shaft front positioning block and the short shaft rear positioning block are respectively connected and fixed to the positioning shaft push rod;

[0008] The long-axis floating block is arranged on the positioning body through the guide surface, and the limit pin is arranged on the positioning body through the mounting hole;

[0009] The front push rod is arranged on the positioning body through the front push rod guide hole, the rear push rod is arranged on the positioning body through the rear push rod guide hole, and the positioning body transition plate is connected and fixed to the positioning body through the connection stopper;

[0010] The spring mounting body and the positioning body transition plate are connected and fixed, and the long-axis floating push rod is connected to the positioning body transition plate;

[0011] The spring, spring top cover, spring bottom cover, long-axis floating spring top cover, long-axis floating spring, and long-axis floating block spring cover are arranged on the spring mounting body;

[0012] The limit pin is installed on the positioning body and the long-axis floating block, the pull rod connecting rod is arranged on the main shaft transition body, and the main shaft transition body connects the spring installation body and the machine tool main shaft.

[0013] Further, in a fixture for a piston having a draft angle on the inner cavity side wall, the positioning shaft push rod includes a positioning shaft hole;

[0014] The short-axis front positioning block includes a short-axis front guide hole, a short-axis front inclined surface, and a front top hole, and the short-axis rear positioning block includes a short-axis rear guide hole, a short-axis rear inclined surface, and a rear top hole;

[0015] The central axis of the positioning body is provided with a guide hole, and the positioning shaft hole is arranged in the guide hole so that the positioning shaft push rod is arranged on the positioning body and can slide freely;

[0016] The short shaft front positioning block and the short shaft rear positioning block are installed in the special-shaped installation cavity, and the short shaft front guide hole and the short shaft rear guide hole are connected in series with the positioning shaft hole position so that the short shaft front positioning block and the short shaft rear positioning block can slide freely on the positioning shaft top rod.

[0017] Further, a fixture for a piston having a draft angle on the inner cavity side wall, the long axis floating block comprises a long axis guide hole and a conical surface;

[0018] The long-axis guide hole is installed on the guide surface, so that the long-axis floating block can slide freely on the positioning body, and the guide surface controls the movement position and angle of the long-axis floating block;

[0019] The mounting hole is arranged on the guide surface;

[0020] The positioning body is symmetrically provided with two front push rod guide holes in the long axis direction, so that the front push rod can slide freely in the holes of the front push rod guide holes;

[0021] Two rear push rod guide holes are symmetrically arranged in the short axis direction of the positioning body, so that the rear push rod can slide freely in the holes of the rear push rod guide holes.

[0022] Further, a fixture for a piston with a draft angle on the inner cavity side wall, the short shaft front positioning block and the short shaft rear positioning block slide freely axially on the positioning shaft push rod, and the positioning shaft push rod slides freely axially in the guide hole of the positioning body;

[0023] The K0 and K1 surfaces on the front inclined surface of the short shaft are respectively in contact with the β inclined surface on the piston for positioning;

[0024] The K2 and K3 surfaces on the rear inclined surface of the short shaft are respectively in contact with the β inclined surface on the piston for positioning;

[0025] The long axis guide hole is installed on the cylindrical surface of the guide surface of the positioning body, and the conical surfaces are respectively contacted with the α conical inclined surfaces on the piston for positioning.

[0026] Further, a clamp for a piston with a draft angle on the inner cavity side wall, the spring mounting body includes a front spring through hole, a rear spring through hole, a spring mounting hole, a floating spring mounting hole, a spring front stop, a bottom cover mounting hole, a spring rear stop, and a spring cover countersunk hole;

[0027] The spring mounting body is symmetrically provided with four spring mounting holes, a mounting spring and a spring top cover;

[0028] The bottom cover mounting hole is provided with a spring bottom cover, and the spring bottom cover fixes one end of the spring;

[0029] The spring mounting body is symmetrically provided with two floating spring mounting holes, and the floating spring mounting holes are used to mount the long-axis floating spring top cover and the long-axis floating spring;

[0030] The spring cover countersunk hole of the spring mounting body is used to install the long-axis floating block spring cover, which is fixed by screws;

[0031] A spring front stop is arranged at the front end of the spring mounting body, and a spring rear stop is arranged at the rear end. The spring front stop is assembled with the rear end stop of the positioning body transition plate and fixed by screws, and the spring rear stop is assembled with the upper stop of the main shaft transition body and fixed by screws.

[0032] Further, a fixture for a piston with a draft angle on the inner cavity side wall, the long-axis floating spring top cover comprises a long-sleeved floating spring top cover cylinder and a long-axis floating spring hole;

[0033] The long-axis floating push rod includes a long sleeve outer cylindrical surface, the spring top cover includes a top cover cylindrical surface and a spring hole, and the spring bottom cover includes a spring mounting hole;

[0034] The long-sleeved floating spring top cover cylinder is installed in the floating spring installation hole of the spring installation body, so that the long-axis floating spring top cover can slide axially freely in the hole of the floating spring installation hole;

[0035] The long-axis floating spring top cover K8 surface is in contact with the tail end surface of the long-axis floating push rod;

[0036] The long-axis floating spring is installed in the long-axis floating spring hole, and the long-axis floating spring pushes the long-axis floating spring top cover to move axially, and pushes the long-axis floating push rod and the long-axis floating block to move axially, so that the conical surface of the long-axis floating block is positioned with the inclined surface α of the piston inner cavity side wall;

[0037] The long-axis floating spring pushes the long-axis floating block to move axially, and the long-axis floating spring pushes the long-axis floating push rod to move axially;

[0038] The top cover cylinder of the spring top cover is installed in the spring mounting hole of the spring mounting body, so that the spring top cover can slide axially freely in the hole of the spring mounting hole;

[0039] The surface of the spring top cover K6 is in contact with the tail end surfaces of the front push rod and the rear push rod;

[0040] The spring is installed in the spring hole to push the front push rod, the rear push rod, the short-axis front positioning block, and the short-axis front positioning block to move axially, so that the short-axis front inclined surface and the short-axis rear inclined surface of the short-axis front positioning block are positioned with the inclined surface β of the side wall of the piston inner cavity;

[0041] The spring installation hole of the spring bottom cover is used to install a spring, fix one end of the spring, and the spring pushes the spring top cover, the front push rod, the rear push rod, the short shaft front positioning block, and the short shaft rear positioning block to move axially;

[0042] The long-axis floating block spring cover limits the long-axis floating spring travel position;

[0043] The long-axis floating block spring cover is provided with a long-axis floating push rod through hole, and the tail end of the long-axis floating push rod passes through the long-axis floating block spring cover.

[0044] Further, a fixture for a piston with a draft angle on the inner cavity side wall, the positioning body transition plate includes a front positioning through hole, a rear positioning through hole, a guide through hole, a rear end stop, and a front end stop;

[0045] The front end of the positioning body transition plate is provided with a front stop, and the rear end is provided with a rear stop;

[0046] The front end stop is assembled with the connection stop of the positioning body and fixed by screws, and the rear end stop is assembled with the spring front stop of the spring installation body and fixed by screws;

[0047] Two guide through holes are symmetrically arranged on the transition plate of the positioning body, and the long sleeve outer cylindrical surface of the long axis floating push rod is installed in the guide through hole, so that the long axis floating push rod can slide freely in the axial direction.

[0048] Further, a fixture for a piston with a draft angle on the inner cavity side wall, wherein the front push rod is installed in the front push rod guide hole of the positioning rod, and the front push rod passes through the front push hole of the short shaft front positioning block;

[0049] The front end face of the front push rod contacts the K5 surface on the front positioning block of the short shaft, and the rear end passes through the front positioning through hole of the positioning body transition plate and the front spring through hole of the spring mounting body in sequence, and the rear end face contacts the K6 surface of the spring top cover;

[0050] The rear push rod is installed in the rear push rod guide hole of the positioning body, and the front end surface contacts the K7 surface of the short shaft rear positioning block;

[0051] The rear end of the rear push rod passes through the rear positioning through hole of the positioning body transition plate and the rear spring through hole of the spring mounting body in sequence, and the rear end surface contacts the K6 surface of the spring top cover.

[0052] Further, a clamp for a piston with a draft angle on the inner cavity side wall, the limit pin includes a limit outer cylindrical surface, the pull rod connecting rod includes a front threaded hole and a rear threaded hole, and the main shaft transition body includes an upper stop;

[0053] The limit pin is installed in the mounting hole on the positioning body, and the limit pin is installed in the angular reset groove on the long-axis floating block. Under the action of the spring force, the K4 surface on the long-axis floating block contacts the limiting outer cylindrical surface of the limit pin to achieve automatic reset of the angular position;

[0054] The front threaded hole is threadedly connected to the tail end of the positioning shaft push rod, and the rear threaded hole is connected to the main shaft cylinder pull rod to transmit the cylinder thrust;

[0055] The pull rod connecting rod is installed in the main shaft transition body hole, and the K9 surface in the main shaft transition body hole limits the axial travel of the pull rod connecting rod to prevent the pull rod connecting rod from causing excessive displacement of the positioning shaft push rod and causing the short shaft front positioning block and the short shaft rear positioning block to fall off from the positioning shaft push rod.

[0056] A method for implementing a clamp for a piston with a draft angle on the inner cavity side wall, comprising the following steps:

[0057] S1: Before piston processing:

[0058] S11: The spindle cylinder pull rod retracts, driving the positioning shaft push rod to move backward;

[0059] S12: Under the action of the spring force, the front push rod is pushed forward, pushing the short-axle front positioning block to move forward until the short-axle front positioning block is blocked by the positioning body and cannot move;

[0060] At the same time, the rear push rod is pushed forward under the action of the spring force, pushing the short-axle rear positioning block to move forward until the short-axle rear positioning block is blocked by the short-axle front positioning block and cannot move;

[0061] S13: Under the action of the long-axis floating spring, the long-axis floating push rod is pushed forward, pushing the long-axis floating block forward until the long-axis floating block is blocked by the limit pin installed on the positioning body and cannot move;

[0062] At the same time, under the action of the limit pin, the long-axis floating block is reset to the designed position in the circumferential direction;

[0063] S14: There is a height difference between the positioning inclined surfaces of the short-axis front positioning block and the short-axis rear positioning block, and the positioning inclined surface of the short-axis rear positioning block is higher than the positioning inclined surface of the short-axis front positioning block; there is also a height difference between the positioning inclined surface of the long-axis floating block and the positioning body inclined surface, and the positioning inclined surface of the long-axis floating block is higher than the positioning body inclined surface;

[0064] S2: Piston processing:

[0065] S21: The inner cavity of the piston is inserted into the fixture, the inclined surface of the piston stop end in the long axis direction fits with the positioning conical surface of the long axis floating block, and the inclined surface of the piston stop end in the short axis direction fits with the inclined surfaces K2 and K3 on the short axis rear positioning block;

[0066] S22: The tailstock pressure plate presses the top surface. During the pressing process, the pressure plate pushes the piston to move toward the spindle end. The piston pushes the long-axis floating block and the short-axis rear positioning block backward in the opposite direction and compresses the corresponding spring at the same time until the height difference between the positioning inclined surfaces of the short-axis front positioning block and the short-axis rear positioning block is eliminated.

[0067] S23: The tailstock pressure plate continues to move toward the spindle end to press the top surface of the piston. The piston pushes the long-axis floating block, the short-axis front positioning block, and the short-axis rear positioning block to move backward in the opposite direction and compresses the corresponding springs at the same time until the inclined surface of the positioning point at the front end of the positioning body contacts the inclined surface of the positioning point on the side of the piston inner cavity. At this time, the piston is in the final clamping state, and the outer circle and top surface of the piston can be rough-machined;

[0068] S3: After the piston is processed:

[0069] S31: The tailstock pressure plate moves backward to release the piston. Because the inner cavity of the piston is tightly fitted with the long-axis floating block, the short-axis front positioning block, and the short-axis rear positioning block and cannot be separated, it moves away from the spindle under the action of the spring thrust until the short-axis front positioning block reaches the travel limit position.

[0070] S32: The spindle cylinder pushes the positioning shaft push rod to move toward the tailstock to disengage the piston from the long-axis floating block, the short-axis front positioning block, and the short-axis rear positioning block. Remove the piston after processing and prepare for the next processing.

[0071] The beneficial effects of the present invention are as follows: through a fixture and an implementation method for a piston with a draft angle on the inner cavity side wall, according to the draft angle characteristics of the piston inner cavity side wall, the fixture positioning point adopts an inclination of the same size as the corresponding positioning point of the piston, and the inclined surface is used to tighten the inner wall of the piston to achieve the function of fixing the inner cavity axis of the piston; the contour shape, size, and inclination of the fixture positioning point are the same as the corresponding position of the piston inner cavity side wall, ensuring that the positioning position shape on the fixture is completely matched with the piston inner cavity positioning position shape, effectively improving the positioning accuracy; when the actual size of the inner cavity side wall of the piston blank changes greatly, because the fixture positioning element can automatically slide forward under the action of the spring force, the inclined surface of the positioning element is always pushed toward the draft angle of the inner wall of the piston, ensuring that the inner wall of the piston is always in a tightened state, automatically adapting to changes in the blank size, ensuring accurate and reliable positioning, thereby controlling the thickness difference of the piston inner cavity wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a schematic diagram of the structure of an aluminum piston in an internal combustion engine.

[0073] Figure 2 It is a schematic diagram of the deflection of the high nickel cast iron ring and the annular inner coolant oil channel.

[0074] Figure 3 This is a schematic diagram showing that the chamfered corners on the inner side of the pin hole and the chamfered corners on the outer side of the piston pin hole are of different sizes.

[0075] Figure 4 Schematic diagram of the draft angle on the piston inner cavity side wall.

[0076] Figure 5 The present invention is a schematic diagram of a fixture structure for a piston having a draft angle on the inner cavity side wall.

[0077] Figure 6 The invention discloses a detailed schematic diagram of a fixture structure for a piston having a draft angle on the inner cavity side wall.

[0078] Figure 7 It is a schematic diagram of the positioning body structure.

[0079] Figure 8 It is a schematic diagram of the positioning shaft push rod structure.

[0080] Fig. 9 It is a schematic diagram of the short-axle front positioning block structure.

[0081] Fig.10 It is a schematic diagram of the short shaft rear positioning block structure.

[0082] Fig.11 It is a schematic diagram of the long-axis floating block structure.

[0083] Fig.12 It is a schematic diagram of the front push rod structure.

[0084] Fig.13It is a schematic diagram of the rear push rod structure.

[0085] Fig.14 It is a schematic diagram of the structure of the positioning body transition plate.

[0086] Fig.15 It is a schematic diagram of the spring top cover structure.

[0087] Fig.16 It is a schematic diagram of the spring mounting structure.

[0088] Fig.17 It is a schematic diagram of the long-axis floating push rod structure.

[0089] Fig.18 It is a schematic diagram of the long-axis floating spring top cover structure.

[0090] Fig.19 It is a schematic diagram of the main shaft transition body structure.

[0091] Fig. 20 It is a schematic diagram of the spring bottom cover structure.

[0092] Fig.21 It is a schematic diagram of the limit pin structure.

[0093] Fig. 22 It is a schematic diagram of the pull rod connecting rod structure.

[0094] Fig.23 This is a schematic diagram of the piston before processing.

[0095] Fig.24 This is a schematic diagram of piston processing.

[0096] Fig.25 This is a schematic diagram of the piston after processing.

[0097] In the figure, I1-piston head, I2-piston pin hole, I3-high nickel cast iron ring, I4-annular internal cooling oil channel, I5-outer chamfer of piston pin hole, I6-inner chamfer of pin hole, I7-high nickel cast iron ring is skewed, I8-annular internal cooling oil channel is skewed, I9-inner chamfer of pin hole is of different sizes, I10-outer chamfer of piston pin hole is of different sizes.

[0098] In the figure, 1-positioning body, 2-positioning shaft push rod, 3-short axis front positioning block, 4-short axis rear positioning block, 5-long axis floating block, 6-front push rod, 7-rear push rod, 8-positioning body transition plate, 9-spring mounting body, 10-long axis floating spring top cover, 11-long axis floating push rod, 12-long axis floating spring, 13-spring top cover, 14-spring bottom cover, 15-spring, 16-long axis floating block spring cover, 17-limit pin, 18-pull rod connecting rod, 19-spindle transition body.

[0099] In the figure, A1-guide surface, A2-guide hole, A3-front push rod guide hole, A4-rear push rod guide hole, A5-mounting hole, A6-connection stopper, A7-front positioning hole, A8-rear positioning hole, A9-guide through hole, A10-rear end stopper, A11-front end stopper, A12-top cover cylinder, A13-spring hole, A14-front spring hole, A15-rear spring hole, A16-spring installation Hole, A18-floating spring mounting hole, A19-spring front stop, A20-bottom cover mounting hole, A21-spring rear stop, A22-long sleeve outer cylindrical surface, A23-spring cover countersunk hole, A25-long axis floating spring hole, A26-long sleeve floating spring top cover cylindrical surface, A27-upper stop, A29-spring mounting hole, A32-limit outer cylindrical surface, A34-rear end threaded hole, A35-front end threaded hole,

[0100] In the figure, A1-1-long axis guide hole, A2-1-positioning axis hole, A2-2-short axis front guide hole, A2-3-short axis rear guide hole, A3-1-front top hole, A3-2-rear top hole, α-1-conical surface, β-1-short axis front bevel, β-2 short axis rear bevel, 1-1-special-shaped mounting cavity, 1-2-long axis direction, 1-3-short axis direction. DETAILED DESCRIPTION

[0101] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0102] As attached Figure 4 As shown in the figure, by combing through the structural characteristics of existing aluminum pistons, for a piston with an inner cavity side wall having a draft angle, it is necessary to use the inner cavity side wall of the piston blank as a positioning reference in the rough turning of the outer circle and top surface of the blank, so as to better control the axial centerline position accuracy of the piston inner cavity surface and ultimately ensure the piston wall thickness difference.

[0103] As attached Figures 5 to 7 As shown, it is specifically a fixture for a piston with a draft angle on the inner cavity side wall, including a positioning body 1, a positioning shaft push rod 2, a short shaft front positioning block 3, a short shaft rear positioning block 4, a long shaft floating block 5, a front push rod 6, a rear push rod 7, a positioning body transition plate 8, a spring mounting body 9, a long shaft floating spring top cover 10, a long shaft floating push rod 11, a long shaft floating spring 12, a spring top cover 13, a spring bottom cover 14, a spring 15, a long shaft floating block spring cover 16, a limit pin 17, a pull rod connecting rod 18, and a main shaft transition body 19;

[0104] The positioning body 1 includes a guide surface A1, a guide hole A2, a special-shaped installation cavity 1-1, a front push rod guide hole A3, a rear push rod guide hole A4, a mounting hole A5, and a connection stop A6;

[0105] The positioning shaft push rod 2 is arranged on the positioning body 1 through the guide hole A2, and the short shaft front positioning block 3 and the short shaft rear positioning block 4 are respectively connected and fixed to the positioning shaft push rod 2;

[0106] The long-axis floating block 5 is arranged on the positioning body 1 through the guide surface A1, and the limit pin 17 is arranged on the positioning body 1 through the mounting hole A5;

[0107] The front push rod 6 is arranged on the positioning body 1 through the front push rod guide hole A3, the rear push rod 7 is arranged on the positioning body 1 through the rear push rod guide hole A4, and the positioning body transition plate 8 is connected and fixed to the positioning body 1 through the connection stop A6;

[0108] The spring mounting body 9 is connected and fixed to the positioning body transition plate 8, and the long-axis floating push rod 11 is connected to the positioning body transition plate 8;

[0109] The spring 15, spring top cover 13, spring bottom cover 14, long axis floating spring top cover 10, long axis floating spring 12, long axis floating block spring cover 16 are arranged on the spring mounting body 9;

[0110] The limit pin 17 is installed on the positioning body 1 and the long-axis floating block 5, and the pull rod connecting rod 18 is arranged on the main shaft transition body 19, and the main shaft transition body 19 connects the spring installation body 9 and the machine tool main shaft.

[0111] As attached Figures 8 to 10 As shown, a clamp for a piston with a draft angle on the inner cavity side wall, the positioning shaft push rod 2 includes a positioning shaft hole position A2-1;

[0112] The short-axis front positioning block 3 includes a short-axis front guide hole A2-2, a short-axis front inclined surface β-1, and a front top hole A3-1. The short-axis rear positioning block 4 includes a short-axis rear guide hole A2-3, a short-axis rear inclined surface β-2, and a rear top hole A3-2.

[0113] The central axis of the positioning body 1 is provided with a guide hole A2, and the positioning shaft hole position A2-1 is arranged in the guide hole A2 so that the positioning shaft push rod 2 is arranged on the positioning body 1 and can slide freely;

[0114] The short shaft front positioning block 3 and the short shaft rear positioning block are installed in the special-shaped installation cavity 1-1, and the short shaft front guide hole A2-2 and the short shaft rear guide hole A2-3 are connected in series with the positioning shaft hole position A2-1 so that the short shaft front positioning block 3 and the short shaft rear positioning block 4 can slide freely on the positioning shaft top rod 2.

[0115] As attached Fig.11 As shown, a fixture for a piston with a draft angle on the inner cavity side wall, the long axis floating block 5 includes a long axis guide hole A1-1, a conical surface α-1, and an angular phase automatic reset surface K4;

[0116] The long-axis guide hole A1-1 is installed on the guide surface A1, so that the long-axis floating block 5 can slide freely on the positioning body 1, and the guide surface A1 controls the movement position and angle of the long-axis floating block 5;

[0117] The mounting hole A5 is provided on the guide surface A1;

[0118] Two front push rod guide holes A3 are symmetrically arranged in the long axis direction 1-2 of the positioning body 1, so that the front push rod 6 can slide freely in the front push rod guide hole A3;

[0119] Two rear push rod guide holes A4 are symmetrically arranged in the short axis direction 1-3 of the positioning body 1, so that the rear push rod 7 can slide freely in the rear push rod guide holes A4.

[0120] Further, a clamp for a piston with a draft angle on the inner cavity side wall, the short shaft front positioning block 3 and the short shaft rear positioning block 4 slide freely axially on the positioning shaft push rod 2, and the positioning shaft push rod 2 slides freely axially in the guide hole A2 of the positioning body 1;

[0121] The K0 and K1 surfaces on the front inclined surface β-1 of the short shaft are respectively in contact with the β inclined surface on the piston for positioning;

[0122] The surfaces K2 and K3 on the short shaft rear inclined surface β-2 are respectively in contact with the β inclined surface on the piston for positioning;

[0123] The long axis guide hole A1-1 is installed on the cylindrical surface of the guide surface A1 of the positioning body 1, and the conical surface α-1 is respectively in contact with the α conical inclined surface on the piston for positioning.

[0124] As attached Fig.16 As shown, a clamp for a piston with a draft angle on the inner cavity side wall, the spring mounting body 9 includes a front spring through hole A14, a rear spring through hole A15, a spring mounting hole A16, a floating spring mounting hole A18, a spring front stop A19, a bottom cover mounting hole A20, a spring rear stop A21, and a spring cover countersunk hole A23;

[0125] The spring mounting body 9 is symmetrically provided with four spring mounting holes A16, a mounting spring 15 and a spring top cover 13;

[0126] The bottom cover mounting hole A20 is used to mount a spring bottom cover 14, which fixes one end of the spring;

[0127] The spring mounting body 9 is symmetrically provided with two floating spring mounting holes A18, and the floating spring mounting holes A18 are used to mount the long-axis floating spring top cover 10 and the long-axis floating spring 12;

[0128] The spring cover counterbore A23 of the spring mounting body 9 is provided with the long axis floating block spring cover 16 and fixed by screws;

[0129] The front end of the spring mounting body 9 is provided with a spring front stop A19, and the rear end is provided with a spring rear stop A21. The front spring stop A19 is assembled with the rear end stop A10 of the positioning body transition plate 8 and fixed by screws, and the rear spring stop A21 is assembled with the upper stop A27 of the main shaft transition body 19 and fixed by screws.

[0130] As attached Fig.15 , 17 18, a fixture for a piston with a draft angle on the inner cavity side wall, wherein the long-axis floating spring top cover 10 includes a long-sleeved floating spring top cover cylinder A26 and a long-axis floating spring hole A25;

[0131] The long-axis floating push rod 11 includes a long sleeve outer cylindrical surface A22, the spring top cover 13 includes a top cover cylindrical surface A12 and a spring hole A13, and the spring bottom cover 14 includes a spring installation hole;

[0132] The long-sleeved floating spring top cover cylinder A26 is installed in the floating spring mounting hole A18 of the spring mounting body 9, so that the long-axis floating spring top cover 10 can slide freely axially in the floating spring mounting hole A18;

[0133] The long axis floating spring top cover 10K8 is in contact with the tail end face of the long axis floating push rod 11;

[0134] The long axis floating spring 12 is installed in the long axis floating spring hole A25, and the long axis floating spring 12 pushes the long axis floating spring top cover 10 to move axially, and pushes the long axis floating push rod 11 and the long axis floating block 5 to move axially, so that the conical surface α-1 of the long axis floating block 5 is positioned with the inclined surface α of the piston inner cavity side wall;

[0135] The long axis floating spring 12 pushes the long axis floating block 5 to move axially, and the long axis floating spring 12 pushes the long axis floating push rod 11 to move axially;

[0136] The top cover cylinder A12 of the spring top cover 13 is installed in the spring mounting hole A16 of the spring mounting body 9, so that the spring top cover 13 can slide freely axially in the spring mounting hole A16;

[0137] The spring top cover 13K6 surface is in contact with the tail end surfaces of the front push rod 6 and the rear push rod 7;

[0138] The spring 15 is installed in the spring hole A13, pushing the front push rod 6, the rear push rod 7, the short-axis front positioning block 3, and the short-axis front positioning block 4 to move axially, so that the short-axis front inclined surface β-1 and the short-axis rear inclined surface β-2 of the short-axis front positioning block 3 are positioned with the inclined surface β of the side wall of the piston inner cavity;

[0139] The spring installation hole A29 of the spring bottom cover 14 is used to install the spring 15, and one end of the spring 15 is fixed. The spring 15 pushes the spring top cover 13, the front push rod 6, the rear push rod 7, the short shaft front positioning block 3, and the short shaft rear positioning block 4 to move axially;

[0140] The long-axis floating block spring cover 16 limits the travel position of the long-axis floating spring 12;

[0141] The long-axis floating block spring cover 16 is provided with a long-axis floating push rod 11 through hole, and the tail end of the long-axis floating push rod 11 passes through the long-axis floating block spring cover 16 .

[0142] As attached Fig.14 As shown, a fixture for a piston with a draft angle on the inner cavity side wall, the positioning body transition plate 8 includes a front positioning through hole A7, a rear positioning through hole A8, a guide through hole A9, a rear end stop A10, and a front end stop A11;

[0143] The front end of the positioning body transition plate 8 is provided with a front end stopper A11, and the rear end is provided with a rear end stopper A10;

[0144] The front end stop A11 is assembled with the connection stop A6 of the positioning body 1 and fixed by screws, and the rear end stop A10 is assembled with the spring front stop A19 of the spring mounting body 9 and fixed by screws;

[0145] Two guide through holes A9 are symmetrically arranged on the positioning body transition plate 8, and the long sleeve outer cylindrical surface A22 of the long axis floating push rod 11 is installed in the guide through hole A9, so that the long axis floating push rod 11 can slide freely in the axial direction.

[0146] As attached Figures 12-13 As shown, a clamp for a piston with a draft angle on the inner cavity side wall, the front push rod 6 is installed in the front push rod guide hole A3 of the positioning rod 1, and the front push rod 6 passes through the front push hole A3-1 of the short shaft front positioning block 3;

[0147] The front end face of the front push rod 6 contacts the K5 surface on the short shaft front positioning block 3, and the rear end passes through the front positioning through hole A7 of the positioning body transition plate 8 and the front spring through hole A14 of the spring mounting body 9 in sequence, and the rear end face contacts the K6 surface of the spring top cover 13;

[0148] The rear push rod 7 is installed in the rear push rod guide hole A4 of the positioning body 1, and the front end surface is in contact with the K7 surface of the short shaft rear positioning block 4;

[0149] The rear end of the rear push rod 7 passes through the rear positioning through hole A8 of the positioning body transition plate 8 and the rear spring through hole A15 of the spring mounting body 9 in sequence, and the rear end surface contacts the K6 surface of the spring top cover 13.

[0150] Further, a clamp for a piston with a draft angle on the inner cavity side wall, the limit pin 17 includes a limit outer cylindrical surface A32, the tie rod connecting rod 18 includes a front threaded hole A35 and a rear threaded hole A34, and the spindle transition body 19 includes an upper stop A27;

[0151] As attached Figures 19 to 22 As shown, the limit pin 17 is installed in the mounting hole A5 on the positioning body 1, and the limit pin 17 is installed in the angular reset groove on the long-axis floating block 5. Under the action of the spring force, the K4 surface on the long-axis floating block 5 contacts the limit outer cylindrical surface A32 of the limit pin 17 to achieve automatic reset of the angular position;

[0152] The front threaded hole A35 is threadedly connected to the tail end of the positioning shaft push rod 2, and the rear threaded hole A34 is connected to the main shaft cylinder pull rod to transmit the cylinder thrust;

[0153] The pull rod connecting rod 18 is installed in the hole of the main shaft transition body 19. The K9 surface in the hole of the main shaft transition body 19 limits the axial travel of the pull rod connecting rod 18 to prevent the pull rod connecting rod 18 from causing excessive displacement of the positioning shaft top rod 2 and causing the short shaft front positioning block 3 and the short shaft rear positioning block 4 to fall off from the positioning shaft top rod 2.

[0154] A method for implementing a clamp for a piston with a draft angle on the inner cavity side wall, comprising the following steps:

[0155] As attached Fig.23 As shown, S1: before piston processing:

[0156] S11: The spindle cylinder pull rod retracts, driving the positioning shaft push rod 2 to move backward;

[0157] S12: Under the action of the spring force, the front push rod 6 is pushed forward, pushing the short-axle front positioning block 3 to move forward until the short-axle front positioning block 3 is blocked by the positioning body 1 and cannot move;

[0158] At the same time, the rear push rod 7 is pushed forward under the action of the spring force, pushing the short-axle rear positioning block 4 to move forward until the short-axle rear positioning block 4 is blocked by the short-axle front positioning block 3 and cannot move;

[0159] S13: Under the action of the long-axis floating spring 12, the long-axis floating push rod 11 is pushed forward, pushing the long-axis floating block 5 forward until the long-axis floating block 5 is blocked by the limit pin 17 installed on the positioning body 1 and cannot move;

[0160] At the same time, under the action of the limit pin 17, the long-axis floating block 5 is angularly reset to the designed position in the circumferential direction;

[0161] S14: There is a height difference between the positioning inclined surfaces of the short-axis front positioning block 3 and the short-axis rear positioning block 4, and the positioning inclined surface of the short-axis rear positioning block 4 is higher than the positioning inclined surface of the short-axis front positioning block 3; there is also a height difference between the positioning inclined surface of the long-axis floating block 5 and the inclined surface of the positioning body 1, and the positioning inclined surface of the long-axis floating block 5 is higher than the inclined surface of the positioning body 1;

[0162] As attached Fig.24 As shown, S2: Piston processing:

[0163] S21: The inner cavity of the piston is inserted into the fixture, the inclined surface of the piston stop end in the long axis direction is fitted with the positioning conical surface α-1 of the long axis floating block 5, and the inclined surface of the piston stop end in the short axis direction is fitted with the inclined surfaces K2 and K3 on the short axis rear positioning block 4;

[0164] S22: The tailstock pressure plate presses the top surface. During the pressing process, the pressure plate pushes the piston to move toward the spindle end, and the piston pushes the long-axis floating block 5 and the short-axis rear positioning block 4 to move backward in the opposite direction while compressing the corresponding spring until the height difference between the positioning inclined surfaces of the short-axis front positioning block 3 and the short-axis rear positioning block 4 is eliminated;

[0165] S23: The tailstock pressure plate continues to move toward the spindle end to press the top surface of the piston. The piston pushes the long-axis floating block 5, the short-axis front positioning block 3, and the short-axis rear positioning block 4 to move backwards and compress the corresponding springs at the same time until the inclined surface of the positioning point at the front end of the positioning body 1 contacts the inclined surface of the positioning point on the side of the piston inner cavity. At this time, the piston is in the final clamping state, and the outer circle and top surface of the piston can be rough-machined;

[0166] As attached Fig.25 As shown, S3: After the piston processing is completed:

[0167] S31: The tailstock pressure plate moves backward to release the piston. Because the inner cavity of the piston is tightly fitted with the long-axis floating block 5, the short-axis front positioning block 3, and the short-axis rear positioning block 4 and cannot be separated, it moves away from the spindle under the action of the spring thrust until the short-axis front positioning block 3 reaches the travel limit position;

[0168] S32: The spindle cylinder pushes the positioning shaft push rod 2 to move the piston toward the tailstock and separate the piston from the long shaft floating block 5, the short shaft front positioning block 3, and the short shaft rear positioning block 4. The piston is removed after processing and prepared for the next processing.

[0169] The present invention provides a fixture and implementation method for a piston with a draft angle on the inner cavity side wall. The three parts of the positioning element, namely, the short-axis front positioning block, the short-axis rear positioning block and the positioning body, are integrated into a whole. The parts are first manufactured as a whole according to the shape of the surface where the positioning point of the piston inner cavity is located. After manufacturing and forming, the parts are cut into three parts according to the shapes of the three parts to form three independent parts, thereby ensuring the relative position accuracy of each positioning surface after the positioning element is assembled and controlling the positioning accuracy of the piston. The contour shape, size and inclination of the positioning point of the positioning element are the same as the corresponding position of the inner cavity side wall of the piston, thereby ensuring that the positioning position shape on the fixture is completely matched with the positioning position shape of the piston inner cavity, thereby effectively improving the positioning accuracy. The driving force for clamping the workpiece is provided by the floating pressure plate on the tailstock, and the driving force provided by the spindle cylinder drives the positioning shaft push rod to perform telescopic movement through the cylinder pull rod, and the piston after processing is removed.

[0170] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A fixture for a piston with a draft angle on the inner cavity side wall, characterized in that: It comprises a positioning body (1), a positioning shaft push rod (2), a short shaft front positioning block (3), a short shaft rear positioning block (4), a long shaft floating block (5), a front push rod (6), a rear push rod (7), a positioning body transition plate (8), a spring mounting body (9), a long shaft floating spring top cover (10), a long shaft floating push rod (11), a long shaft floating spring (12), a spring top cover (13), a spring bottom cover (14), a spring (15), a long shaft floating block spring cover (16), a stop pin (17), a pull rod connecting rod (18), and a main shaft transition body (19); The positioning body (1) comprises a guide surface (A1), a guide hole (A2), a special-shaped installation cavity (1-1), a front push rod guide hole (A3), a rear push rod guide hole (A4), a mounting hole (A5), and a connection stop (A6); The positioning shaft push rod (2) is arranged on the positioning body (1) through the guide hole (A2), and the short shaft front positioning block (3) and the short shaft rear positioning block (4) are respectively connected and fixed to the positioning shaft push rod (2); The long-axis floating block (5) is arranged on the positioning body (1) via a guide surface (A1), and the limit pin (17) is arranged on the positioning body (1) via a mounting hole (A5); The front push rod (6) is arranged on the positioning body (1) through the front push rod guide hole (A3), the rear push rod (7) is arranged on the positioning body (1) through the rear push rod guide hole (A4), and the positioning body transition plate (8) is connected and fixed to the positioning body (1) through the connection stop (A6); The spring mounting body (9) and the positioning body transition plate (8) are connected and fixed, and the long-axis floating push rod (11) is connected to the positioning body transition plate (8); The spring (15), the spring top cover (13), the spring bottom cover (14), the long-axis floating spring top cover (10), the long-axis floating spring (12), and the long-axis floating block spring cover (16) are arranged on the spring mounting body (9); The limit pin (17) is mounted on the positioning body (1) and the long axis floating block (5), the pull rod connecting rod (18) is arranged on the main shaft transition body (19), and the main shaft transition body (19) connects the spring mounting body (9) and the machine tool main shaft.

2. A clamp for a piston with a draft angle on the inner cavity side wall as claimed in claim 1, characterized in that: The positioning shaft push rod (2) comprises a positioning shaft hole (A2-1); The short-axis front positioning block (3) includes a short-axis front guide hole (A2-2), a short-axis front inclined surface (β-1), and a front top hole (A3-1); the short-axis rear positioning block (4) includes a short-axis rear guide hole (A2-3), a short-axis rear inclined surface (β-2), and a rear top hole (A3-2); The central axis of the positioning body (1) is provided with a guide hole (A2), and the positioning shaft hole position (A2-1) is arranged in the guide hole (A2) so that the positioning shaft push rod (2) is arranged on the positioning body (1) and can slide freely; The short shaft front positioning block (3) and the short shaft rear positioning block are installed in the special-shaped installation cavity (1-1), and the short shaft front guide hole (A2-2) and the short shaft rear guide hole (A2-3) are connected in series with the positioning shaft hole position (A2-1) so that the short shaft front positioning block (3) and the short shaft rear positioning block (4) can slide freely on the positioning shaft top rod (2).

3. A clamp for a piston with a draft angle on the inner cavity side wall according to claim 1, characterized in that: The long-axis floating block (5) comprises a long-axis guide hole (A1-1) and a conical surface (α-1); The long axis guide hole (A1-1) is installed on the guide surface (A1), so that the long axis floating block (5) can slide freely on the positioning body (1), and the guide surface (A1) controls the movement position and angle of the long axis floating block (5); The mounting hole (A5) is arranged on the guide surface (A1); The positioning body (1) is symmetrically provided with two front push rod guide holes (A3) in the long axis direction (1-2), so that the front push rod (6) can slide freely in the front push rod guide holes (A3); Two rear push rod guide holes (A4) are symmetrically arranged in the short axis direction (1-3) of the positioning body (1), so that the rear push rod (7) can slide freely in the rear push rod guide holes (A4).

4. A clamp for a piston with a draft angle on the inner cavity side wall according to claim 2, characterized in that: The short shaft front positioning block (3) and the short shaft rear positioning block (4) slide freely axially on the positioning shaft push rod (2), and the positioning shaft push rod (2) slides freely axially in the guide hole (A2) of the positioning body (1); The K0 and K1 surfaces on the front inclined surface (β-1) of the short shaft are respectively in contact with the β inclined surface on the piston for positioning; The K2 and K3 surfaces on the rear inclined surface (β-2) of the short shaft are respectively in contact with the β inclined surface on the piston for positioning; The long axis guide hole (A1-1) is installed on the cylindrical surface of the guide surface (A1) of the positioning body (1), and the conical surface (α-1) is respectively in contact with the α conical inclined surface on the piston for positioning.

5. A clamp for a piston with a draft angle on the inner cavity side wall according to claim 1, characterized in that: The spring mounting body (9) comprises a front spring through hole (A14), a rear spring through hole (A15), a spring mounting hole (A16), a floating spring mounting hole (A18), a spring front stop (A19), a bottom cover mounting hole (A20), a spring rear stop (A21), and a spring cover countersunk hole (A23); The spring mounting body (9) is symmetrically provided with four spring mounting holes (A16), a mounting spring (15) and a spring top cover (13); The bottom cover mounting hole (A20) is used to mount a spring bottom cover (14), and the spring bottom cover (14) fixes one end of the spring; The spring mounting body (9) is symmetrically provided with two floating spring mounting holes (A18), and the floating spring mounting holes (A18) are used to mount the long-axis floating spring top cover (10) and the long-axis floating spring (12); The spring cover countersunk hole (A23) of the spring mounting body (9) is installed with the long axis floating block spring cover (16) and fixed by screws; The front end of the spring mounting body (9) is provided with a spring front stop (A19), and the rear end is provided with a spring rear stop (A21); the front spring stop (A19) is assembled with the rear end stop (A10) of the positioning body transition plate (8) and fixed by screws; the rear spring stop (A21) is assembled with the upper stop (A27) of the main shaft transition body (19) and fixed by screws.

6. A clamp for a piston with a draft angle on the inner cavity side wall according to claim 5, characterized in that: The long-axis floating spring top cover (10) comprises a long-sleeved floating spring top cover cylinder (A26) and a long-axis floating spring hole (A25); The long-axis floating push rod (11) includes a long sleeve outer cylindrical surface (A22), the spring top cover (13) includes a top cover cylindrical surface (A12) and a spring hole (A13), and the spring bottom cover (14) includes a spring mounting hole; The long-sleeved floating spring top cover cylinder (A26) is installed in the floating spring mounting hole (A18) of the spring mounting body (9), so that the long-axis floating spring top cover (10) can slide freely axially in the floating spring mounting hole (A18); The K8 surface of the long-axis floating spring top cover (10) contacts the end surface of the tail end of the long-axis floating top rod (11); The long-axis floating spring (12) is installed in the long-axis floating spring hole (A25), and the long-axis floating spring (12) pushes the long-axis floating spring top cover (10) to move axially, pushes the long-axis floating push rod (11) and the long-axis floating block (5) to move axially, so that the conical surface (α-1) of the long-axis floating block (5) is positioned with the inclined surface α of the piston inner cavity side wall; The long-axis floating spring (12) pushes the long-axis floating block (5) to move axially, and the long-axis floating spring (12) pushes the long-axis floating push rod (11) to move axially; The top cover cylindrical surface (A12) of the spring top cover (13) is installed in the spring mounting hole (A16) of the spring mounting body (9), so that the spring top cover (13) can slide freely axially in the spring mounting hole (A16); The spring top cover (13) has a K6 surface in contact with the tail end surfaces of the front push rod (6) and the rear push rod (7); The spring (15) is installed in the spring hole (A13) to push the front push rod (6), the rear push rod (7), the short shaft front positioning block (3), and the short shaft front positioning block (4) to move axially, so that the short shaft front inclined surface (β-1) and the short shaft rear inclined surface (β-2) of the short shaft front positioning block (3) are positioned with the inclined surface β of the side wall of the piston inner cavity; The spring mounting hole (A29) of the spring bottom cover (14) is used to mount the spring (15), fix one end of the spring (15), and the spring (15) pushes the spring top cover (13), the front push rod (6), the rear push rod (7), the short shaft front positioning block (3), and the short shaft rear positioning block (4) to move axially; The long-axis floating block spring cover (16) limits the travel position of the long-axis floating spring (12); The long-axis floating block spring cover (16) is provided with a long-axis floating push rod (11) through hole, and the tail end of the long-axis floating push rod (11) passes through the long-axis floating block spring cover (16).

7. A clamp for a piston with a draft angle on the inner cavity side wall according to claim 1, characterized in that: The positioning body transition plate (8) comprises a front positioning through hole (A7), a rear positioning through hole (A8), a guide through hole (A9), a rear end stop (A10), and a front end stop (A11); The front end of the positioning body transition plate (8) is provided with a front end stop (A11), and the rear end is provided with a rear end stop (A10); The front end stop (A11) is assembled with the connection stop (A6) of the positioning body (1) and fixed by screws, and the rear end stop (A10) is assembled with the spring front stop (A19) of the spring mounting body (9) and fixed by screws; Two guide through holes (A9) are symmetrically arranged on the positioning body transition plate (8), and the long sleeve outer cylindrical surface (A22) of the long axis floating push rod (11) is installed in the guide through hole (A9), so that the long axis floating push rod (11) can slide freely in the axial direction.

8. A fixture for a piston with a draft angle on the inner cavity side wall according to claim 5, characterized in that: The front push rod (6) is installed in the front push rod guide hole (A3) of the positioning rod (1), and the front push rod (6) passes through the front push hole (A3-1) of the short shaft front positioning block (3); The front end surface of the front push rod (6) contacts the K5 surface on the short shaft front positioning block (3), and the rear end passes through the front positioning through hole (A7) of the positioning body transition plate (8) and the front spring through hole (A14) of the spring mounting body (9) in sequence, and the rear end surface contacts the K6 surface of the spring top cover (13); The rear push rod (7) is installed in the rear push rod guide hole (A4) of the positioning body (1), and the front end surface contacts the K7 surface of the short shaft rear positioning block (4); The rear end of the rear push rod (7) passes through the rear positioning through hole (A8) of the positioning body transition plate (8) and the rear spring through hole (A15) of the spring mounting body (9) in sequence, and the rear end surface contacts the K6 surface of the spring top cover (13).

9. A fixture for a piston with a draft angle on the inner cavity side wall according to claim 1, characterized in that: The limiting pin (17) includes a limiting outer cylindrical surface (A32), the pull rod connecting rod (18) includes a front threaded hole (A35) and a rear threaded hole (A34), and the main shaft transition body (19) includes an upper stop (A27); The limit pin (17) is installed in the installation hole (A5) on the positioning body (1), and the limit pin (17) is installed in the angular reset groove on the long axis floating block (5). Under the action of the spring force, the K4 surface on the long axis floating block (5) contacts the limit outer cylindrical surface (A32) of the limit pin (17), thereby realizing automatic reset of the angular position. The front threaded hole (A35) is threadedly connected to the tail end of the positioning shaft push rod (2), and the rear threaded hole (A34) is connected to the main shaft cylinder pull rod to transmit the cylinder thrust; The pull rod connecting rod (18) is installed in the hole of the main shaft transition body (19), and the K9 surface in the hole of the main shaft transition body (19) limits the axial travel of the pull rod connecting rod (18), thereby preventing the pull rod connecting rod (18) from driving the positioning shaft top rod (2) to excessively move and causing the short shaft front positioning block (3) and the short shaft rear positioning block (4) to fall off from the positioning shaft top rod (2).

10. A method for realizing a clamp for a piston with a draft angle on the inner cavity side wall, based on the clamp for a piston with a draft angle on the inner cavity side wall according to any one of claims 1 to 9, characterized in that: The steps are: S1: Before piston processing: S11: The main shaft cylinder pull rod retracts, driving the positioning shaft push rod (2) to move backwards; S12: Under the action of the spring force, the front push rod (6) is pushed forward, pushing the short shaft front positioning block (3) to move forward until the short shaft front positioning block (3) is blocked by the positioning body (1) and cannot move; At the same time, under the action of the spring force, the rear push rod (7) is pushed forward, pushing the short shaft rear positioning block (4) to move forward until the short shaft rear positioning block (4) is blocked by the short shaft front positioning block (3) and cannot move; S13: Under the action of the long-axis floating spring (12), the long-axis floating push rod (11) is pushed forward, pushing the long-axis floating block (5) forward until the long-axis floating block (5) is blocked by the limit pin (17) installed on the positioning body (1) and cannot move; At the same time, under the action of the limit pin (17), the long-axis floating block (5) is angularly reset to a designed position in the circumferential direction; S14: There is a height difference between the positioning inclined surfaces of the short-axis front positioning block (3) and the short-axis rear positioning block (4), and the positioning inclined surface of the short-axis rear positioning block (4) is higher than the positioning inclined surface of the short-axis front positioning block (3); there is also a height difference between the positioning inclined surface of the long-axis floating block (5) and the inclined surface of the positioning body (1), and the positioning inclined surface of the long-axis floating block (5) is higher than the inclined surface of the positioning body (1); S2: Piston processing: S21: The inner cavity of the piston is inserted into the fixture, the inclined surface of the piston stop end in the long axis direction is fitted with the positioning conical surface (α-1) of the long axis floating block (5) for positioning, and the inclined surface of the piston stop end in the short axis direction is fitted with the inclined surfaces K2 and K3 on the short axis rear positioning block (4) for positioning; S22: The tailstock pressure plate presses the top surface. During the pressing process, the pressure plate pushes the piston to move toward the spindle end. The piston pushes the long-axis floating block (5) and the short-axis rear positioning block (4) to move backward in the opposite direction and compresses the corresponding spring at the same time until the height difference between the positioning inclined surfaces of the short-axis front positioning block (3) and the short-axis rear positioning block (4) is eliminated. S23: The tailstock pressure plate continues to move toward the spindle end to press the piston top surface, and the piston pushes the long-axis floating block (5), the short-axis front positioning block (3), and the short-axis rear positioning block (4) in the opposite direction to move backward while compressing the corresponding springs until the inclined surface of the positioning point at the front end of the positioning body (1) contacts the inclined surface of the positioning point on the side of the piston inner cavity. At this time, the piston is in the final clamping state, and the outer circle and top surface of the piston can be rough-machined; S3: After the piston is processed: S31: The tailstock pressure plate moves backward to release the piston. Because the inner cavity of the piston is tightly fitted with the long-axis floating block (5), the short-axis front positioning block (3) and the short-axis rear positioning block (4) and cannot be separated, the piston moves away from the spindle under the thrust of the spring until the short-axis front positioning block (3) reaches the travel limit position. S32: The spindle cylinder pushes the positioning shaft push rod (2) toward the tailstock to move the piston and disengage the piston from the long shaft floating block (5), the short shaft front positioning block (3), and the short shaft rear positioning block (4). The piston is removed after the processing is completed and prepared for the next processing.

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