Fixture for piston without pattern draft on side wall of inner cavity
By designing a piston fixture with no draft angle on the inner cavity sidewall, the radial expansion and contraction motion of the expanding claw is used to accurately position the piston inner cavity. This solves the problems of cast iron ring tilting and poor cooling caused by the draft angle of the inner cavity sidewall in the manufacturing of aluminum pistons for internal combustion engines, and achieves high-precision positioning and wall thickness difference control of the piston inner cavity.
Patent Information
- Application Number
- CN202422819900.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2034-11-19
AI Technical Summary
During the manufacturing process of aluminum pistons for internal combustion engines, the lack of draft angle on the inner cavity sidewalls makes it difficult to meet the design requirements for the tilt and position of the high-nickel cast iron rings. This leads to problems such as uneven thickness of the cast iron ring grooves, misalignment of the annular internal cooling oil passages, and misalignment of the piston pin holes, affecting the piston weight and cooling effect, resulting in poor engine operation.
Design a fixture for pistons without draft angle on the inner cavity sidewall, including a fixture body, a short-axis front conical ejector rod, a short-axis front expanding claw, a short-axis rear conical ejector rod, and a long-axis rear conical ejector rod. The piston inner cavity is accurately positioned by the radial expansion and contraction movement of the expanding claw, and the symmetrical movement of the expanding claw is achieved by using the machine tool spindle cylinder and spring to drive the expanding claw, ensuring the positioning accuracy of the piston inner cavity.
This improved the positioning accuracy of the piston cavity, ensured accurate control of wall thickness difference, avoided problems such as unqualified piston weight and poor cooling, and achieved high-precision machining of the piston cavity.
Smart Images
Figure CN223889526U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of aluminum piston manufacturing for internal combustion engines, and in particular to a fixture for pistons without draft angle on the inner cavity sidewall. Background Technology
[0002] Internal combustion engine aluminum pistons typically have a high-nickel cast iron ring inlaid on the outer circumference of the piston head. This cast iron ring is cast together with the aluminum piston body during piston casting. An annular internal cooling oil passage is cast inside the piston head, as shown in the attached image. Figure 1 As shown, the inner edge of the piston pin hole is generally designed with a machined rounded corner, while the outer edge of the piston pin hole is designed with a chamfered corner. When the piston wall thickness difference is large, the following problems will occur: (See attached image) Figure 2 As shown, the tilt and position of the high-nickel cast iron ring cannot meet the design requirements, leading to uneven thickness of the cast iron material on the upper and lower sides of the ring groove. In severe cases, there may be no cast iron material available for machining on the lower side of the ring groove. It can also cause the annular internal cooling oil passage in the piston head to deviate beyond tolerance, resulting in poor cooling of the piston head and perforation during engine operation. (See attached image) Figure 3 As shown, this will also cause the inner and outer casting surfaces of the piston to be skewed, resulting in problems with the rounded corners of the inner edge of the piston pin hole and the poor symmetry of the chamfered corners of the outer edge of the piston pin hole. The other machined surfaces of the piston that meet the casting surface will also be skewed. 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 cast surface, while the top surface of the piston is a machined surface. The piston top thickness is the distance from the center cast surface of the inner top to the machined top surface of the piston. Generally, the tolerance requirements are high. Due to the large casting tolerance, it is difficult to control the final top thickness tolerance, which ultimately affects the weight of the product. Utility Model Content
[0004] The purpose of this invention is to address the above-mentioned problems in the prior art by providing a fixture for pistons without draft angle on the inner cavity sidewall.
[0005] A clamp for a piston with no draft angle on the inner cavity sidewall includes a clamp body, a short shaft front conical ejector rod, a short shaft front expansion claw, a short shaft rear conical ejector rod, a short shaft rear expansion claw, a long shaft rear conical ejector rod, a long shaft rear expansion claw, a long shaft spring, a short shaft rear end spring, a pull ring, a pull plate, a sleeve, a retaining ring, a pull rod, a front end cover plate, an internally threaded cylindrical pin, a hexagonal flange nut, a hexagonal thin nut, and screws;
[0006] The clamping body includes a conical surface, a short shaft front conical guide hole, a short shaft rear conical guide hole, a long shaft rear conical guide hole, a front expansion claw guide square hole, a rear expansion claw guide square hole, a rear expansion claw guide stepped square hole, a pull plate guide hole, a retaining ring mounting hole, a connecting assembly stop, and a positioning pin hole.
[0007] The clamping body is connected to the short shaft front cone guide hole and the short shaft front cone top rod;
[0008] The clamping body is connected by a short shaft front cone guide hole and a short shaft rear cone top rod;
[0009] The clamping body is connected to the long shaft rear cone guide hole and the long shaft rear cone top rod;
[0010] The clamping body is connected to the front expansion claw guide square hole and the short shaft front expansion claw;
[0011] The clamping body is connected to the rear expansion claw guide square hole and the short shaft rear expansion claw;
[0012] The clamping body is connected to the rear expansion claw guide stepped square hole and the long shaft rear expansion claw;
[0013] The clamp body is fixed with a retaining ring through a retaining ring mounting hole;
[0014] The long shaft rear tapered top rod connects to the short shaft rear end spring. The sleeve and the long shaft spring are assembled in the long shaft rear tapered top rod. The pull ring and pull plate are fixed. The internal threaded cylindrical pin is connected to the clamp body and the pull ring respectively. The pull rod is installed on the pull plate. The front end cover plate is set in front of the clamp body. The hexagonal flange nut and hexagonal thin nut lock the short shaft front tapered top rod.
[0015] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall, wherein the short shaft front cone ejector rod includes a short sleeve front cone outer circle, a short sleeve rear sliding cylindrical surface, a short front rod dovetail groove, a positioning cylindrical surface, and a locking thread;
[0016] The short-shaft rear cone top rod includes a short-sleeve rear cone outer circle, a top rod guide hole, a short rear rod dovetail groove, and a short-sleeve rear cylindrical surface;
[0017] The long shaft rear cone top rod includes a long shaft rear cone outer circle, a long rear rod dovetail groove, a long shaft rear hole, and a long sleeve spring hole;
[0018] The short-axis front expansion claw includes a square face of the short front expansion claw and a dovetail groove of the short front claw;
[0019] The short-axis rear expansion claw includes a square surface of the short rear expansion claw and a dovetail groove of the short rear claw;
[0020] The long-axis rear expansion claw includes a stepped square surface of the long rear expansion claw and a dovetail groove of the long rear claw.
[0021] The pull plate includes an outer circle of the pull plate, an upper hole of the pull plate, an annular countersunk hole for spring mounting, and a countersunk hole of the pull plate.
[0022] The short shaft front cone guide hole and the short sleeve front cone outer circle are clearance-fitted, allowing the short shaft front cone push rod to slide freely in the clamp body axis;
[0023] The short shaft rear cone guide hole and the short sleeve rear cone outer circle are clearance-fitted, allowing the short shaft rear cone top rod to slide freely in the clamping body axis;
[0024] The guide hole of the long shaft rear cone and the outer circle of the long shaft rear cone are clearance-fitted, allowing the long shaft rear cone top rod to slide freely in the clamping body axis;
[0025] The square hole for the front expansion claw and the square surface for the short front expansion claw are clearance-fitted, allowing the short-shaft front expansion claw to slide along the free axis of the clamping body.
[0026] The rear expansion claw guide square hole and the short rear expansion claw square surface are clearance-fitted, allowing the short shaft rear expansion claw to slide along the free axis of the clamping body.
[0027] The rear expansion claw guide stepped square hole and the long rear expansion claw stepped square surface are clearance-fitted, allowing the long shaft rear expansion claw to slide along the free axis of the clamping body.
[0028] The guide hole of the pull plate and the outer circle of the pull plate are fitted with a clearance, allowing the pull plate to slide freely along the clamping body axis.
[0029] Furthermore, a fixture for a piston with no draft angle on the inner cavity sidewall, wherein the retaining ring includes a retaining ring outer circle and a stroke adjustment threaded hole;
[0030] The conical surface of the clamping body is positioned in contact with the long axis positioning points N2-0 and N2-1 of the piston's inner cavity.
[0031] The connecting assembly stop of the clamp body is fixed to the machine tool spindle by screws;
[0032] The retaining ring mounting hole and the outer circle of the retaining ring are assembled and fixed.
[0033] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall, wherein the short shaft front cone guide hole and the short sleeve front cone outer circle are in clearance fit;
[0034] The guide hole of the top rod and the sliding cylindrical surface of the short sleeve are fitted with a clearance.
[0035] Furthermore, a clamp for a piston with no draft angle on the inner cavity sidewall, wherein the sleeve includes an outer cylindrical surface;
[0036] The pull ring includes a cylindrical pull ring surface and an anti-rotation positioning pin hole;
[0037] The outer cylindrical surface of the sleeve is fitted into the rear hole of the long shaft, the rear hole of the long shaft is fitted into the rear cylindrical surface of the short sleeve, the long shaft spring is installed in the spring hole of the long sleeve, and the long shaft spring is fitted into the outer cylindrical surface of the sleeve.
[0038] The positioning cylinder and the upper hole of the pull plate are assembled and connected, and the short shaft front cone top rod and the pull plate are fastened by locking threads and locking nuts;
[0039] The cylindrical surface of the pull ring is fitted into the countersunk hole of the pull plate, and the pull ring and the pull plate are fixed with screws;
[0040] One end of the internally threaded cylindrical pin is installed in the positioning pin hole of the clamp body with an interference fit, and the other end of the internally threaded cylindrical pin is installed in the anti-rotation positioning pin hole on the pull ring with a clearance fit.
[0041] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall, wherein the end face K7 of the short shaft rear cone ejector rod is connected to the rear end spring of the short shaft;
[0042] One end of the long-axis spring contacts the end face K8 of the long-sleeve spring hole, and the other end of the long-axis spring contacts the bottom face K9 of the spring mounting annular countersunk hole.
[0043] The short shaft rear end spring pushes the short shaft rear cone top rod to move axially forward, and the short rear rod dovetail groove of the short shaft rear cone top rod drives the short shaft rear expansion claw to slide radially outward to tighten the positioning point on the inner wall of the piston.
[0044] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall is provided with two short front rod dovetail grooves on the short shaft front cone ejector rod. The two short front rod dovetail grooves and the short front claw dovetail groove are in sliding clearance fit. The cone surface K1 surface on the short shaft front cone ejector rod is in contact with the inclined surface K4 surface on the short shaft front claw.
[0045] The short shaft rear cone top rod is provided with two short rear rod dovetail grooves. The two short rear rod dovetail grooves are in sliding clearance fit with the short rear claw dovetail groove. The cone surface K2 surface on the short shaft rear cone top rod is in contact with the inclined surface K5 surface on the short shaft rear expansion claw.
[0046] The long shaft rear cone top rod is provided with two long rear rod dovetail grooves. The two long rear rod dovetail grooves are in sliding clearance fit with the long rear claw dovetail groove. The cone surface K3 on the long shaft rear cone top rod is in contact with the inclined surface K6 on the long shaft rear expansion claw.
[0047] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall, wherein the pull rod includes a pull rod assembly stop and a pull rod thread.
[0048] The beneficial effects of this utility model are as follows: A fixture for pistons without draft angle on the inner cavity sidewall is used. Based on the characteristic of the piston's inner cavity sidewall having no draft angle, the circumferential arc of the fixture's positioning surface is at the same position as the corresponding piston. The radial expansion and contraction of the fixture's own expanding claws is used to clamp the inner wall of the piston. The circumferential shape and size of the fixture's positioning point are the same as the corresponding position of the piston's inner cavity sidewall, resulting in high positioning accuracy of the piston's inner cavity. Even when the actual dimensions of the piston blank's inner cavity sidewall vary significantly, the high precision and symmetrical movement of the fixture's expanding claws ensure the fixture's positioning accuracy and accurately control the wall thickness difference of the piston's inner cavity. The fixture has three pairs of expanding claws. The expansion and contraction of the first pair of expanding claws at the front end of the fixture is driven by the machine tool spindle cylinder, while the other two pairs of expanding claws are driven by springs within the fixture to produce an expansion action, and the retraction action is driven by a cylinder. Attached Figure Description
[0049] Figure 1 This is a schematic diagram of an aluminum piston structure for an internal combustion engine.
[0050] Figure 2 This is a schematic diagram of the high-nickel cast iron ring and the deflection of the annular internal cooling oil passage.
[0051] Figure 3 This is a schematic diagram showing that the rounded 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.
[0052] Figure 4 This is a schematic diagram showing the piston's inner cavity sidewall without draft angle.
[0053] Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 These are schematic diagrams of a fixture structure for pistons without draft angle on the inner cavity sidewall.
[0054] Figure 11 , Figure 12 , Figure 13 All of these are schematic diagrams of the clamp body structure.
[0055] Figure 14 This is a schematic diagram of the short-axis front cone top rod structure.
[0056] Figure 15 This is a schematic diagram showing the fit between the short-axis front cone top rod and the clamping body.
[0057] Figure 16 This is a schematic diagram of the short-axis rear cone top rod structure.
[0058] Figure 17 , Figure 18 These are all schematic diagrams showing the fit between the short-axis front cone top rod and the clamping body.
[0059] Figure 19 , Figure 20 , Figure 21 , Figure 22 All are schematic diagrams of the long-axis rear cone top rod structure.
[0060] Figure 23 This is a schematic diagram of the short-axis front expansion claw structure.
[0061] Figure 24 This is a schematic diagram showing the fit between the short-axis front expansion claw and the clamping body.
[0062] Figure 25 This is a schematic diagram of the short-axis rear expansion claw structure.
[0063] Figure 26 This is a schematic diagram showing the fit between the short-shaft rear expansion claw and the clamping body.
[0064] Figure 27 This is a schematic diagram of the long-axis rear expansion claw structure.
[0065] Figure 28 This is a schematic diagram showing the fit between the long-axis rear expansion claw and the clamping body.
[0066] Figure 29 This is a schematic diagram of the pull plate structure.
[0067] Figure 30 This is a cross-sectional view of the pull plate structure.
[0068] Figure 31 This is a schematic diagram of the retaining ring structure.
[0069] Figure 32 This is a cross-sectional view of the retaining ring structure.
[0070] Figure 33 This is a structural diagram.
[0071] Figure 34 , Figure 36 This is a schematic diagram of the pull ring structure.
[0072] Figure 35 This is a cross-sectional view of the pull ring structure.
[0073] Figure 37 This is a schematic diagram of the tie rod structure.
[0074] Figure 38 , Figure 40 These are schematic diagrams showing the state of the fixture before processing and the loosened position.
[0075] Figure 39 yes Figure 38 Detailed structural diagram at point P1.
[0076] Figure 41 yes Figure 40 Detailed structural diagram at point P2.
[0077] Figure 42 yes Figure 40 Detailed structural diagram at P3.
[0078] Figure 43 , Figure 44 These are all schematic diagrams showing the piston's inner cavity fitted into the clamp.
[0079] Figure 45 yes Figure 43 Detailed structural diagram at P4.
[0080] Figure 46 yes Figure 43 Detailed structural diagram at P5.
[0081] Figure 47 yes Figure 44 Detailed structural diagram at P6.
[0082] In the diagram, I1 is the piston head, I2 is the piston pin hole, I3 is the high-nickel cast iron ring, I4 is the annular internal cooling oil passage, I5 is the chamfer on the outer side of the piston pin hole, I6 is the rounded corner on the inner side of the pin hole, I7 is the skewed high-nickel cast iron ring, I8 is the skewed annular internal cooling oil passage, I9 is the uneven size of the rounded corner on the inner side of the pin hole, and I10 is the uneven size of the chamfer on the outer side of the piston pin hole.
[0083] In the diagram, 1-clamp body, 2-short shaft front conical ejector rod, 3-short shaft front expansion claw, 4-short shaft rear conical ejector rod, 5-short shaft rear expansion claw, 6-long shaft rear conical ejector rod, 7-long shaft rear expansion claw, 8-long shaft spring, 9-short shaft rear end spring, 10-pull ring, 11-pull plate, 12-sleeve, 13-retaining ring, 14-pull rod, 15-front end cover plate, 16-internal threaded cylindrical pin, 17-hexagonal flange nut, 18-hexagonal thin nut, 19-screw, 20-piston.
[0084] In the diagram, BA1 is a conical surface, BA3 is a short front bar dovetail groove, BA5 is a short rear bar dovetail groove, BA7 is a long rear bar dovetail groove, BA9 is a short front claw dovetail groove, BA11 is a short rear claw dovetail groove, and BA13 is a long rear claw dovetail groove.
[0085] In the diagram, BD1 - short shaft front tapered guide hole, BD2 - short shaft rear tapered guide hole, BD3 - long shaft rear tapered guide hole, BD4 - pull plate guide hole, BD5 - retaining ring mounting hole, BD6 - connecting assembly stop, BD9 - positioning pin hole, BD11 - short sleeve front tapered outer circle, BD12 - short sleeve rear sliding cylindrical surface, BD13 - positioning cylindrical surface, BD14 - locking thread, BD15 - short sleeve rear tapered outer circle, BD16 - push rod guide hole, BD17 - short sleeve rear cylindrical surface, BD18 - long shaft rear tapered outer circle, BD19 - long shaft rear hole, BD20 - long sleeve spring hole, BD22 - pull plate outer circle, BD23 - pull plate countersunk hole, BD25 - pull plate upper hole, BD26 - pull rod assembly stop, BD30 - retaining ring outer circle, BD33 - sleeve outer cylindrical surface, BD37 - pull ring cylindrical surface, BD38 - anti-rotation positioning pin hole, BD41 - pull rod thread.
[0086] In the diagram, BL1 is the square hole for guiding the front expansion claw, BL3 is the square hole for guiding the rear expansion claw, BL5 is the stepped square hole for guiding the rear expansion claw, BL7 is the annular countersunk hole for spring mounting, BL9 is the square face of the short front expansion claw, BL11 is the square face of the short rear expansion claw, and BL13 is the stepped square face of the long rear expansion claw. Detailed Implementation
[0087] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model are now described with reference to the accompanying drawings.
[0088] As attached Figure 4 As shown, by analyzing the structural characteristics of existing aluminum pistons, for a type of piston with no draft angle on the inner cavity sidewall, the inner cavity sidewall of the piston 20 blank needs to be used as a positioning reference during the rough turning of the outer circle and top surface of the blank. This is necessary to better control the positional accuracy of the axis of the inner cavity surface of the piston 20 and ultimately ensure the piston wall thickness difference.
[0089] As attached Figures 5-13 As shown, this is a fixture for a piston without draft angle on the inner cavity sidewall, including a fixture body 1, a short shaft front conical ejector rod 2, a short shaft front expansion claw 3, a short shaft rear conical ejector rod 4, a short shaft rear expansion claw 5, a long shaft rear conical ejector rod 6, a long shaft rear expansion claw 7, a long shaft spring 8, a short shaft rear end spring 9, a pull ring 10, a pull plate 11, a sleeve 12, a retaining ring 13, a pull rod 14, a front end cover plate 15, an internally threaded cylindrical pin 16, a hexagonal flange nut 17, a hexagonal thin nut 18, and a screw 19;
[0090] The clamping body 1 includes a conical surface BA1, a short shaft front conical guide hole BD1, a short shaft rear conical guide hole BD2, a long shaft rear conical guide hole BD3, a front expansion claw guide square hole BL1, a rear expansion claw guide square hole BL3, a rear expansion claw guide stepped square hole BL5, a pull plate guide hole BD4, a retaining ring mounting hole BD5, a connecting assembly stop BD6, and a positioning pin hole BD9.
[0091] The clamping body 1 is connected to the short shaft front cone guide hole BD1 and the short shaft front cone top rod 2;
[0092] The clamping body 1 is connected to the short shaft front cone guide hole BD1 and the short shaft rear cone top rod 4;
[0093] The clamping body 1 is connected to the long shaft rear cone guide hole BD3 and the long shaft rear cone top rod 6;
[0094] The clamping body 1 is connected to the short shaft front expansion claw 3 through the front expansion claw guide square hole BL1;
[0095] The clamping body 1 is connected to the short shaft rear expansion claw 5 through the rear expansion claw guide square hole BL3;
[0096] The clamping body 1 is connected to the rear expansion claw 7 via a rear expansion claw guide stepped square hole BL5 and a long shaft rear expansion claw 7.
[0097] The clamping body 1 fixes the retaining ring 13 through the retaining ring mounting hole BD5;
[0098] The long shaft rear cone top rod 6 is connected to the short shaft rear end spring 9. The sleeve 12 and the long shaft spring 8 are assembled in the long shaft rear cone top rod 6. The pull ring 10 and the pull plate 11 are fixed. The internal thread cylindrical pin 16 is connected to the clamp 1 and the pull ring 10 respectively. The pull rod 14 is installed on the pull plate 11. The front end cover plate 15 is set in front of the clamp body 1. The hexagonal flange nut 17 and the hexagonal thin nut 18 lock the short shaft front cone top rod 2.
[0099] As attached Figures 7-30 As shown, a fixture for a piston without draft angle on the inner cavity sidewall is provided. The short shaft front cone ejector rod 2 includes a short sleeve front cone outer circle BD11, a short sleeve rear sliding cylindrical surface BD12, a short front rod dovetail groove BA3, a positioning cylindrical surface BD13, and a locking thread BD14.
[0100] The short-shaft rear cone top rod 4 includes a short-sleeve rear cone outer circle BD15, a top rod guide hole BD16, a short rear rod dovetail groove BA5, and a short-sleeve rear cylindrical surface BD17.
[0101] The long shaft rear cone top rod 6 includes a long shaft rear cone outer circle BD18, a long rear rod dovetail groove BA7, a long shaft rear hole BD19, and a long sleeve spring hole BD20.
[0102] The short-axis front expansion claw 3 includes a short front expansion claw square surface BL9 and a short front claw dovetail groove BA9;
[0103] The short-shaft rear expansion claw 5 includes a short rear expansion claw square surface BL11 and a short rear claw dovetail groove BA11;
[0104] The long-axis rear expansion claw 7 includes a long rear expansion claw stepped square surface BL13 and a long rear claw dovetail groove BA13;
[0105] The pull plate 11 includes an outer circle BD22, an upper hole BD25, a spring mounting annular countersunk hole BL7, and a countersunk hole BD23.
[0106] The short-axis front cone guide hole BD1 and the short-sleeve front cone outer circle BD11 are fitted together to allow the short-axis front cone push rod 2 to slide freely in the clamp body 1.
[0107] The short shaft rear cone guide hole BD2 and the short sleeve rear cone outer circle BD15 are fitted with a clearance, allowing the short shaft rear cone top rod 4 to slide freely in the clamp body 1 in the free axis.
[0108] The long shaft rear cone guide hole BD3 and the long shaft rear cone outer circle BD18 are clearance-fitted, allowing the long shaft rear cone top rod 6 to slide freely in the clamp body 1 in the free axis;
[0109] The front expansion claw guide square hole BL1 and the short front expansion claw square surface BL9 are fitted together to allow the short shaft front expansion claw 3 to slide freely along the clamping body 1.
[0110] The rear expansion claw guide square hole BL3 and the short rear expansion claw square surface BL11 are fitted together to allow the short shaft rear expansion claw 5 to slide freely along the clamping body 1.
[0111] The rear expansion claw guide stepped square hole BL5 and the long rear expansion claw stepped square surface BL13 are fitted together to allow the long shaft rear expansion claw 7 to slide freely in the clamping body 1.
[0112] The guide hole BD4 and the outer circle BD22 of the pull plate are fitted with a clearance, allowing the pull plate 11 to slide freely along the clamping body 1.
[0113] As attached Figures 31-32 As shown, a clamp for a piston with no draft angle on the inner cavity sidewall is provided, wherein the retaining ring 13 includes a retaining ring outer circle BD30 and a stroke adjustment threaded hole;
[0114] The conical surface BA1 of the clamping body 1 is in contact with the long axis positioning points N2-0 and N2-1 of the piston 20.
[0115] The connecting assembly stop BD6 of the fixture body 1 is connected and fixed to the machine tool spindle by screws 19;
[0116] The retaining ring mounting hole BD5 and the outer circle BD30 of the retaining ring are assembled and fixed to limit the axial sliding limit stroke position of the pull plate 11.
[0117] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall, wherein the short shaft front cone guide hole BD1 and the short sleeve front cone outer circle BD11 are clearance-fitted to ensure the movement accuracy of the short shaft front cone ejector rod 2 in the short shaft front cone guide hole BD1;
[0118] The clearance fit between the push rod guide hole BD16 and the short-sleeve rear sliding cylindrical surface BD12 ensures the movement accuracy of the short-shaft rear tapered push rod 4 in the push rod guide hole BD16.
[0119] As attached Figures 31-36 As shown, a clamp for a piston with no draft angle on the inner cavity sidewall is provided, wherein the sleeve 12 includes an outer cylindrical surface BD33.
[0120] The pull ring includes a pull ring cylindrical surface BD37 and an anti-rotation positioning pin hole BD38;
[0121] The outer cylindrical surface BD33 of the sleeve is fitted into the rear hole BD19 of the long shaft, the rear hole BD19 of the long shaft is fitted into the rear cylindrical surface BD17 of the short sleeve, the long shaft spring 8 is installed in the spring hole BD20 of the long sleeve, and the long shaft spring 8 is fitted into the outer cylindrical surface BD33 of the sleeve.
[0122] The positioning cylindrical surface BD13 and the upper hole BD25 of the pull plate are assembled and connected, and the short shaft front cone top rod 2 and the pull plate 11 are fastened by the locking thread BD14 and the locking nut;
[0123] The cylindrical surface BD37 of the pull ring is assembled in the countersunk hole BD23 of the pull plate, and the pull ring 10 and the pull plate 11 are fixed by screws 19.
[0124] One end of the internally threaded cylindrical pin 16 is installed in the positioning pin hole BD9 of the clamp body 1 with an interference fit, and the other end of the internally threaded cylindrical pin 16 is installed in the anti-rotation positioning pin hole BD38 on the pull ring 10 with a clearance fit, so that the pull ring 10 can slide freely along the axial direction of the internally threaded cylindrical pin 16.
[0125] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall is provided, wherein the end face K7 of the short shaft rear cone ejector rod 4 is connected to the short shaft rear end spring 9, and under the action of the spring force, the short shaft rear expansion claw 5 is pushed to move radially outward to tighten the positioning point of the inner cavity sidewall of the piston 20.
[0126] The long shaft spring 8 pushes the long shaft rear cone top rod 6 to move axially forward, and the long rear rod dovetail groove BA7 of the long shaft rear cone top rod 6 drives the long shaft rear expansion claw 7 to slide radially outward to tighten the positioning point of the inner cavity side wall of the piston 20.
[0127] One end of the long shaft spring 8 is in contact with the end face K8 of the long sleeve spring hole BD20, and the other end of the long shaft spring 8 is in contact with the bottom face K9 of the spring mounting annular countersunk hole BL7. Under the elastic force of the long shaft spring 8, the long shaft rear cone top rod 6 pushes the long shaft rear expansion claw 7 to move radially outward through the long rear rod dovetail groove BA7 to tighten the positioning point of the inner cavity side wall of the piston 20.
[0128] The short shaft rear end spring 9 pushes the short shaft rear cone top rod 4 to move axially forward, and the short rear rod dovetail groove BA5 of the short shaft rear cone top rod 4 drives the short shaft rear expansion claw 5 to slide radially outward to tighten the positioning point of the inner cavity side wall of the piston 20.
[0129] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall is provided with two short front rod dovetail grooves BA3 on the short shaft front cone ejector rod 2. The two short front rod dovetail grooves BA3 and the short front claw dovetail groove BA9 are in sliding clearance fit. The cone surface K1 on the short shaft front cone ejector rod 2 and the inclined surface K4 on the short shaft front claw 3 are in contact with each other and are relative sliding surfaces. During operation, they are the force-bearing surfaces.
[0130] When the short shaft front cone top rod 2 moves axially back and forth, it drives the short shaft front expansion claw 3 to perform radial extension and retraction in the front expansion claw guide square hole BL1 of the clamp body 1 through the dovetail groove BA3 of the short front rod, thereby realizing the action of tightening or loosening the positioning points N4-0 and N4-1 on the inner cavity sidewall of the piston 20.
[0131] The short shaft rear cone top rod 4 is provided with two short rear rod dovetail grooves BA5. The two short rear rod dovetail grooves BA5 are in sliding clearance fit with the short rear claw dovetail groove BA11. The cone surface K2 surface on the short shaft rear cone top rod 4 is in contact with the inclined surface K5 surface on the short shaft rear expansion claw 5, which is a relative sliding surface and a force-bearing surface during operation.
[0132] When the short shaft rear cone top rod 4 moves back and forth axially, it drives the short shaft rear expansion claw 5 to make radial extension and retraction movements in the rear expansion claw guide square hole BL3 of the clamp body 1 through the dovetail groove BA5 of the short rear rod, thereby realizing the action of tightening or loosening the positioning points N3-0 and N3-1 on the inner cavity sidewall of the piston 20.
[0133] The long shaft rear cone top rod 6 is provided with two long rear rod dovetail grooves BA7. The two long rear rod dovetail grooves BA7 are in sliding clearance fit with the long front claw dovetail groove BA13. The cone surface K3 surface on the long shaft rear cone top rod 6 is in contact with the inclined surface K6 surface on the long shaft rear expansion claw 7, which is a relative sliding surface and a force-bearing surface during operation.
[0134] When the long shaft rear cone top rod 6 moves back and forth axially, it drives the long shaft rear expansion claw 7 to perform radial extension and retraction movement in the rear expansion claw guide stepped square hole BL5 of the clamping body through the dovetail groove BA7 of the long rear rod, so as to realize the action of tightening or loosening the positioning points N1-0 and N1-1 on the inner cavity side wall of the piston 20.
[0135] As attached Figure 37 As shown, a clamp for a piston with no draft angle on the inner cavity sidewall is provided, wherein the pull rod includes a pull rod mounting stop BD26 and a pull rod thread BD41;
[0136] After the pull plate 11 and the pull ring 10 are assembled, they form the movement space of the long-axis rear cone top rod 6, which is used to limit the axial movement stroke of the long-axis rear cone top rod 6.
[0137] During the release process, the pull ring 10 pulls the long shaft rear cone rod 6 to move backward, causing the long shaft rear expansion claw 7 to retract inward and release the piston 20;
[0138] During the clamping process, the pull plate 11 moves forward under the push of the pull rod 14, the axial travel restriction of the pull ring 10 on the long shaft rear cone top rod 6 is automatically canceled, the pull plate 11 compresses the long shaft spring 8, and under the action of the spring force, the long shaft rear cone top rod 6 pushes the long shaft rear expansion claw 7 outward through the inclined surface of the long rear rod dovetail groove BA7, and tightens the inner cavity side wall of the piston 20.
[0139] Set 12 isolates the long shaft spring 8 and the short shaft rear end spring 9 to prevent mutual interference during movement.
[0140] Furthermore, a fixture for a piston without draft angle on the inner cavity sidewall, wherein the retaining ring 13 restricts the movement stroke of the pull plate 11, and the stroke position of the pull plate 11 is adjusted by adjusting the position of the threaded hole.
[0141] The rear end of the pull rod 14 is connected to the main spindle cylinder pull rod through the pull rod thread BD41, which transmits the thrust or pull force of the main spindle cylinder to provide action for the fixture.
[0142] The front cover plate 15 prevents chips from entering the clamp body 1;
[0143] The internally threaded cylindrical pin 16 restricts the pull ring 10 from rotating during movement.
[0144] A fixture for pistons without draft angle on the inner cavity sidewall, the principle of which is as follows:
[0145] As attached Figures 38-42 As shown, S1: The state of the fixture before and after machining:
[0146] S11: The main spindle cylinder pull rod retracts, driving the short shaft front cone push rod 2 to move to the right and through the short front rod dovetail groove BA3, driving the short shaft front expansion claw 3 to retract to the center;
[0147] S12: The stepped surface K10 on the front cone top rod 2 of the short shaft drives the rear cone top rod (4) of the short shaft to move to the right, and drives the rear expansion claw 5 of the short shaft to retract to the center through the dovetail groove BA5 of the short rear rod;
[0148] S13: At the same time, the short shaft front cone top rod 2, pull plate 11, pull ring 10, and pull rod 14 are connected and fixed as a whole by screws and nuts. When the short shaft front cone top rod 2 moves to the right, the pull ring 10 also moves to the right and drives the long shaft rear cone top rod 6 to move to the right through the step surface K11 on the long shaft rear cone top rod 6.
[0149] S14: The long rear dovetail groove BA7 of the long shaft rear cone top rod 6 drives the long shaft rear expansion claw 7 to retract the pull rod 14 towards the center, and the limit position of the rightward movement is controlled by the limit screw on the retaining ring 13.
[0150] As attached Figures 43-47 As shown, S2: The inner cavity of piston 20 is fitted onto the clamp:
[0151] S21: The piston 20 is positioned with its long axis positioning points N2-0 and N2-1 in contact with the conical surface BA1 of the clamping body 1. At this time, the gaps between the inner wall of the piston and the clamping body 1, the long axis rear expansion claw 7, the short axis front expansion claw 3, and the short axis rear expansion claw 5 are Wa, Wb, and Wc, respectively. The main shaft cylinder moves to the left, causing the pull rod 14, pull plate 11, pull ring 10, and short axis front cone push rod 2 to move to the left as a whole.
[0152] S22: The pull ring 10 moves to the left to release the step surface K11 of the long shaft rear cone top rod 6. Under the action of the spring force, the long shaft spring 8 pushes the long shaft rear cone top rod 6 to move to the left. The long rear rod dovetail groove BA7 on the long shaft rear cone top rod 6 pushes the two long shaft rear expansion claws 7 to both sides to simultaneously expand out of the inner cavity side wall positioning points N1-0 and N1-1 of the tensioning piston 20.
[0153] S23: The short shaft front cone push rod 2 moves to the left, and the upper step surface K10 is released from the short shaft rear cone push rod 4. The short shaft rear cone push rod 4 moves to the left under the spring force of the short shaft rear end spring 9. Through the short rear rod dovetail groove BA5 of the short shaft rear cone push rod 4, it pushes the two short shaft rear expansion claws 5 to both sides to simultaneously expand out of the inner cavity side wall positioning points N3-0 and N3-1 of the tensioning piston 20; S24: The short shaft front cone push rod 2 moves to the left, and through the short rear rod dovetail groove BA5, it pushes the two short shaft front expansion claws 3 to both sides to simultaneously expand out of the inner cavity side wall positioning points N4-0 and N4-1 of the tensioning piston 20;
[0154] S25: The tailstock pressure plate presses the top surface, and the piston 20 is in an accurate positioning and reliable clamping state, which allows for rough machining of the outer circle and top surface of the piston 20.
[0155] This solution utilizes a fixture designed for pistons without draft angles on their inner cavity sidewalls. Based on this characteristic, the circumferential arc of the fixture's positioning surface corresponds to the piston's position. The radial expansion and contraction of the fixture's own expanding claws tightens the inner wall of the piston 20. The circumferential shape and size of the fixture's positioning point correspond to the piston's inner cavity sidewall, ensuring high positioning accuracy. The expanding claws exhibit high precision and symmetrical movement, guaranteeing the fixture's positioning accuracy and accurately controlling the piston's inner cavity wall thickness difference even when the actual dimensions of the piston blank's inner cavity sidewall vary significantly. The fixture has three pairs of expanding claws. The expansion and contraction of the first pair of claws at the front end of the fixture is driven by a machine tool spindle cylinder, while the other two pairs are driven by springs within the fixture to extend, and retract by a cylinder. The three pairs of expanding claws move synchronously to tighten the inner wall of the piston 20, and the claw stroke is adjustable.
[0156] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.
Claims
1. A fixture for pistons without draft angle on the inner cavity sidewall, characterized in that, Includes clamping body (1), short shaft front cone ejector rod (2), short shaft front expansion claw (3), short shaft rear cone ejector rod (4), short shaft rear expansion claw (5), long shaft rear cone ejector rod (6), long shaft rear expansion claw (7), long shaft spring (8), short shaft rear end spring (9), pull ring (10), pull plate (11), sleeve (12), retaining ring (13), pull rod (14), front end cover plate (15), internal thread cylindrical pin (16), hexagonal flange nut (17), hexagonal thin nut (18), screw (19); The clamping body (1) includes a conical surface (BA1), a short shaft front conical guide hole (BD1), a short shaft rear conical guide hole (BD2), a long shaft rear conical guide hole (BD3), a front expansion claw guide square hole (BL1), a rear expansion claw guide square hole (BL3), a rear expansion claw guide stepped square hole (BL5), a pull plate guide hole (BD4), a retaining ring mounting hole (BD5), a connecting assembly stop (BD6), and a positioning pin hole (BD9). The clamping body (1) is connected to the short shaft front cone guide hole (BD1) and the short shaft front cone top rod (2); The clamping body (1) is connected to the short shaft front cone guide hole (BD1) and the short shaft rear cone top rod (4) through the short shaft front cone guide hole (BD1); The clamping body (1) is connected to the long shaft rear cone guide hole (BD3) and the long shaft rear cone top rod (6); The clamping body (1) is connected to the short shaft front expansion claw (3) through the front expansion claw guide square hole (BL1); The clamping body (1) is connected to the short shaft rear expansion claw (5) through the rear expansion claw guide square hole (BL3); The clamping body (1) is connected to the rear expansion claw guide stepped square hole (BL5) and the long shaft rear expansion claw (7) through the rear expansion claw guide. The clamping body (1) fixes the retaining ring (13) through the retaining ring mounting hole (BD5); The long shaft rear cone top rod (6) is connected to the short shaft rear end spring (9). The sleeve (12) and the long shaft spring (8) are assembled in the long shaft rear cone top rod (6). The pull ring (10) and the pull plate (11) are fixed. The internal thread cylindrical pin (16) is connected to the clamp body (1) and the pull ring (10) respectively. The pull rod (14) is installed on the pull plate (11). The front end cover plate (15) is set in front of the clamp body (1). The hexagonal flange nut (17) and the hexagonal thin nut (18) lock the short shaft front cone top rod (2).
2. The fixture for a piston with no draft angle on the inner cavity sidewall according to claim 1, characterized in that, The short-shaft front cone top rod (2) includes a short-sleeve front cone outer circle (BD11), a short-sleeve rear sliding cylindrical surface (BD12), a short-sleeve front rod dovetail groove (BA3), a positioning cylindrical surface (BD13), and a locking thread (BD14). The short-shaft rear cone top rod (4) includes a short-sleeve rear cone outer circle (BD15), a top rod guide hole (BD16), a short rear rod dovetail groove (BA5), and a short-sleeve rear cylindrical surface (BD17). The long shaft rear cone top rod (6) includes a long shaft rear cone outer circle (BD18), a long rear rod dovetail groove (BA7), a long shaft rear hole (BD19), and a long sleeve spring hole (BD20). The short-axis front expansion claw (3) includes a short front expansion claw square surface (BL9) and a short front expansion claw dovetail groove (BA9); The short-shaft rear expansion claw (5) includes a short rear expansion claw square surface (BL11) and a short rear claw dovetail groove (BA11). The long-axis rear expansion claw (7) includes a stepped square surface (BL13) and a dovetail groove (BA13) for the long rear expansion claw. The pull plate (11) includes an outer circle (BD22), an upper hole (BD25), a spring mounting annular countersunk hole (BL7), and a countersunk hole (BD23). The short-axis front cone guide hole (BD1) and the short-sleeve front cone outer circle (BD11) are fitted with a clearance, allowing the short-axis front cone push rod (2) to slide freely in the clamp body (1); The short shaft rear cone guide hole (BD2) and the short sleeve rear cone outer circle (BD15) are fitted with a clearance, allowing the short shaft rear cone top rod (4) to slide freely in the clamp body (1); The long shaft rear cone guide hole (BD3) and the long shaft rear cone outer circle (BD18) are clearance-fitted, allowing the long shaft rear cone top rod (6) to slide freely in the clamping body (1); The front expansion claw guide square hole (BL1) and the short front expansion claw square surface (BL9) are fitted with a clearance, allowing the short shaft front expansion claw (3) to slide freely along the clamping body (1); The rear expansion claw guide square hole (BL3) and the short rear expansion claw square surface (BL11) are fitted with a clearance, allowing the short shaft rear expansion claw (5) to slide freely along the clamping body (1); The rear expansion claw guide stepped square hole (BL5) and the long rear expansion claw stepped square surface (BL13) are fitted together with a clearance, so that the long shaft rear expansion claw (7) can slide freely in the clamping body (1). The guide hole (BD4) and the outer circle (BD22) of the pull plate are fitted together with a clearance, allowing the pull plate (11) to slide freely along the axial direction of the clamping body (1).
3. A fixture for a piston with no draft angle on the inner cavity sidewall according to claim 1, characterized in that, The retaining ring (13) includes a retaining ring outer circle (BD30) and a stroke adjustment threaded hole; The conical surface (BA1) of the clamping body (1) is in contact with the long axis positioning points N2-0 and N2-1 of the piston (20); The connecting assembly stop (BD6) of the fixture body (1) is connected and fixed to the machine tool spindle by screws (19); The retaining ring mounting hole (BD5) and the outer circle of the retaining ring (BD30) are assembled and fixed.
4. A fixture for a piston with no draft angle on the inner cavity sidewall according to claim 2, characterized in that, The short shaft front cone guide hole (BD1) and the short sleeve front cone outer circle (BD11) are clearance-fitted; The top rod guide hole (BD16) and the short sleeve rear sliding cylindrical surface (BD12) are clearance-fitted.
5. A fixture for a piston with no draft angle on the inner cavity sidewall according to claim 2, characterized in that, The sleeve (12) includes an outer cylindrical surface (BD33); The pull ring includes a pull ring cylindrical surface (BD37) and an anti-rotation positioning pin hole (BD38). The outer cylindrical surface (BD33) of the sleeve is fitted into the rear hole (BD19) of the long shaft, the rear hole (BD19) of the long shaft is fitted into the rear cylindrical surface (BD17) of the short sleeve, the long shaft spring (8) is installed in the spring hole (BD20) of the long sleeve, and the long shaft spring (8) is fitted into the outer cylindrical surface (BD33) of the sleeve. The positioning cylinder (BD13) and the upper hole (BD25) of the pull plate are assembled and connected, and the short shaft front cone top rod (2) and the pull plate (11) are fastened by locking thread (BD14) and locking nut; The cylindrical surface (BD37) of the pull ring is fitted into the countersunk hole (BD23) of the pull plate, and the pull ring (10) and the pull plate (11) are fixed by screws (19); One end of the internal thread cylindrical pin (16) is installed in the positioning pin hole (BD9) of the clamp body (1) with an interference fit, and the other end of the internal thread cylindrical pin (16) is installed in the anti-rotation positioning pin hole (BD38) on the pull ring (10) with a clearance fit.
6. A fixture for a piston with no draft angle on the inner cavity sidewall according to claim 2, characterized in that, The end face K7 of the short shaft rear cone top rod (4) is connected to the short shaft rear end spring (9). One end of the long-axis spring (8) is in contact with the end face K8 of the long sleeve spring hole (BD20), and the other end of the long-axis spring (8) is in contact with the bottom face K9 of the spring mounting annular countersunk hole (BL7). The short shaft rear end spring (9) pushes the short shaft rear cone top rod (4) to move forward axially. The short rear rod dovetail groove (BA5) of the short shaft rear cone top rod (4) drives the short shaft rear expansion claw (5) to slide radially outward to tighten the positioning point of the inner cavity side wall of the piston (20).
7. A fixture for a piston with no draft angle on the inner cavity sidewall according to claim 6, characterized in that, The short-axis front cone top rod (2) is provided with two short front rod dovetail grooves (BA3), and the two short front rod dovetail grooves (BA3) and the short front claw dovetail groove (BA9) are in sliding clearance fit. The cone surface K1 surface on the short-axis front cone top rod (2) is in contact with the inclined surface K4 surface on the short-axis front claw (3). The short shaft rear cone top rod (4) is provided with two short rear rod dovetail grooves (BA5). The two short rear rod dovetail grooves (BA5) and the short rear claw dovetail groove (BA11) are in sliding clearance fit. The cone surface K2 surface on the short shaft rear cone top rod (4) is in contact with the inclined surface K5 surface on the short shaft rear expansion claw (5). The long shaft rear cone top rod (6) is provided with two long rear rod dovetail grooves (BA7). The two long rear rod dovetail grooves (BA7) and the long rear claw dovetail groove (BA13) are in sliding clearance fit. The cone surface K3 surface on the long shaft rear cone top rod (6) is in contact with the inclined surface K6 surface on the long shaft rear expansion claw (7).
8. A fixture for a piston with no draft angle on the inner cavity sidewall according to claim 7, characterized in that, The tie rod includes a tie rod assembly stop (BD26) and a tie rod thread (BD41).