A new fixture for thin-wall external turning

Abstract

A new type of fixture for thin-walled external cylindrical turning belongs to the technical field of cutting manufacturing fixtures. The structure is composed of a fixed chassis, a fixture seat, a cylinder, a cylinder cover, an adjusting screw, a fixing screw, a liquid plastic, a slider, and a sealing ring to form an integral sealing device. By screwing the adjusting screw in and out, the slider is driven to move, and the size of the space occupied by the liquid plastic is changed. The pressure generated exerts pressure on the cylinder wall. The pressure is distributed along the shape of the inner wall curved surface, and the clamping and loosening of the workpiece can be achieved through the change of pressure. The liquid plastic expands due to heat, causing the cylinder wall to bend and deform. The contact surface between the deformed cylinder wall and the workpiece is greatly increased, making it easier to tighten and greatly reducing the cutter, so that the parallelism and cylindricality of the cut outer circle can be very high, greatly improving the processing accuracy and efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of cutting manufacturing fixtures and relates to a fixture, in particular to a new type of liquid plastic fixture used for thin-wall external cylindrical turning. Background Art

[0002] At present, when turning the outer circle, the fixtures used in production can easily cause the parts to deform due to stress and heat. In particular, when processing thin-walled sleeve parts, their surfaces not only have requirements for shape accuracy, dimensional accuracy and surface roughness, but also have high position accuracy requirements. The processing accuracy of thin-walled parts has always been a problem that needs to be solved in the industry. High-precision thin-walled sleeves are difficult to clamp and are prone to processing deformation. Modern process equipment is developing towards high precision and high efficiency to meet the needs of production; some fixtures that were poorly made, low in precision, cumbersome and laborious to operate, and had a long production cycle in the past can no longer meet the requirements of production. In order to meet the processing of thin-walled sleeve parts, it is necessary to design some fixtures with high positioning accuracy, easy to use, and low cost that can improve production efficiency. Summary of the invention

[0003] The purpose of the present invention is to address the shortcomings of existing thin-wall sleeve turning technology and propose a new clamp for thin-wall external cylindrical turning. By changing the shape of the inner wall of the traditional clamping mechanism, the parallelism and cylindricity of the turned external cylindrical surface can be improved, thereby improving the processing accuracy and efficiency.

[0004] The technical solution of the present invention is: a new type of fixture for thin-walled external cylindrical turning, including a fixed chassis; characterized in that: a fixture seat is connected to one side of the fixed chassis, and the fixture seat is fastened to the fixed chassis by a fixing screw, a cylinder is connected to the top of the fixture seat, and a cylinder cover is connected to the other end of the cylinder, the inner wall of the cylinder is provided with a curved surface, liquid plastic is provided in the inner cavity of the cylinder, a threaded through hole is provided at the center of the cylinder cover, an adjusting screw is provided in the threaded through hole, the top end of the adjusting screw is round-headed, the adjusting screw is in contact with a slider inside the cylinder cover, a sealing ring is provided between the slider and the cylinder cover, and the adjusting screw pushes the slider and the sealing ring to slide synchronously to compress the volume of the liquid plastic, and the processed workpiece is sleeved on the outer surface of the cylinder for cutting.

[0005] The inner surface of the cylinder is composed of two straight line segments and a curved surface that are smoothly connected. The two straight line segments are provided with internal threads, and the curved surface segment is a fish belly-shaped quartic surface.

[0006] The outer diameter of the boss on the clamp seat is provided with a thread, the diameter of which is the same as the inner diameter of the lower end of the cylinder, the inner diameter of the upper end of the cylinder is the same as the outer diameter of the cylinder cover, and the outer diameter of the cylinder cover is also provided with a thread, and the connection method between them is external welding and internal thread connection.

[0007] The slider and the cylinder cover are clearance-matched, a sealing groove is arranged in the middle of the slider, a sealing ring is arranged in the sealing groove, and the slider drives the sealing ring to slide synchronously.

[0008] The beneficial effects of the present invention are as follows: the present invention provides a new type of fixture for thin-walled external cylindrical turning, which is structurally composed of a fixed chassis, a fixture seat, a cylinder, a cylinder cover, an adjusting screw, a fixing screw, a liquid plastic, a slider, and a sealing ring connected to form an integral sealing device. By screwing the adjusting screw in and out, the size of the space occupied by the liquid plastic is changed, and the pressure generated will cause pressure on the cylinder wall. The pressure is distributed along the shape of the inner wall curved surface, and the clamping and loosening of the workpiece can be achieved by the change of pressure. The traditional fixture adopts a cylinder wall of equal wall thickness, which will lead to insufficient friction during clamping, and will cause the tool to bend when turning a thin-walled ring, resulting in more cutting in the middle and less at both ends, and the cutting result is a concave curve; when the cylinder wall changes into a fish belly type quartic curve shape, the liquid plastic expands due to heat, causing the cylinder wall to bend and deform, and the deformed cylinder wall is similar to the shape of the cylinder wall of equal wall thickness, and the contact surface between the cylinder wall and the thin-walled ring is greatly improved, which is easier to tighten, and the tool is greatly reduced, so that the parallelism and cylindricality of the cut outer circle are very high, which greatly improves the processing accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0010] Figure 2 It is a schematic diagram of the full cross-section structure of the present invention.

[0011] Figure 3 It is a schematic diagram of the cutting state of the present invention.

[0012] Figure 4 This is a simplified schematic diagram of the stress and deformation of the cylinder wall with equal wall thickness.

[0013] Figure 5 It is a simplified schematic diagram of the stress deformation of the cylinder wall of the present invention.

[0014] In the figure: fixed chassis 1, fixture seat 2, cylinder 3, cylinder cover 4, adjusting screw 5, fixing screw 6, curved surface 7, liquid plastic 8, slider 9, sealing ring 10, workpiece 11, tool 12, straight simply supported beam 13, deflection curve 1 14, fish belly quartic simply supported beam 15, deflection curve 2 16. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the accompanying drawings:

[0016] like Figure 1-3As shown, a new type of fixture for thin-walled external cylindrical turning includes a fixed chassis 1; a fixture seat 2 is connected to one side of the fixed chassis 1, and the fixture seat 2 is fastened to the fixed chassis 1 by a fixing screw 6. A cylinder 3 is welded on the fixture seat 2, and a cylinder cover 4 is welded on the other end of the cylinder 3. The inner wall of the cylinder 3 is provided with a curved surface 7, and the inner cavity of the cylinder 3 is provided with a liquid plastic 8. The center of the cylinder cover 4 is provided with a threaded through hole, and an adjusting screw 5 is provided in the threaded through hole. The top of the adjusting screw 5 is round-headed, and the adjusting screw 5 contacts with a slider 9 inside the cylinder cover 4. A sealing ring 10 is provided between the slider 9 and the cylinder cover 4. The adjusting screw 8 pushes the slider 9 and the sealing ring 10 to slide synchronously, compressing the volume of the liquid plastic 8, and the processed workpiece 11 is sleeved on the outer surface of the cylinder 3 for cutting.

[0017] like Figure 1-3 As shown, a new type of clamp for thin-walled external cylindrical turning, the inner surface of the cylinder 3 is composed of two straight segments and a curved surface 7 that are smoothly connected, the two straight segments are provided with internal threads, and the curved surface segment 7 is a fish belly-shaped quartic surface; the diameter of the boss on the clamp seat 2 is the same as the inner diameter of the lower end of the cylinder 3, the inner diameter of the upper end of the cylinder 3 is the same as the outer diameter of the cylinder cover 4, and the connection method is external welding and internal threaded connection; the slider 9 and the cylinder cover 4 are clearance fit, a sealing groove is provided in the middle of the slider, a sealing ring 10 is provided in the sealing groove, and the slider 9 drives the sealing ring 10 to slide synchronously.

[0018] like Figure 1-5 As shown, the working principle of a new type of clamp for thin-walled external cylindrical turning is as follows: the thin-walled workpiece 11 is clamped on the cylinder 3, and then the adjusting screw 5 is continuously screwed in, and the screw pushes the slider 9 to reduce the space for the liquid plastic. Since the liquid plastic 8 is incompressible, it will transmit pressure to the cylinder wall 3, thereby clamping the thin-walled workpiece 11.

[0019] When the workpiece starts to be turned, the heat generated by the cutting is transferred to the liquid plastic through the cylinder wall. The liquid plastic expands due to the heat, which will exert a force on the inner wall of the cylinder wall, causing it to bend and deform. For the traditional uniform wall thickness liquid plastic fixture, when the tool 12 is used to turn the thin-walled ring 11, the cutting amount in the middle is larger and the two ends are smaller. Because the uniform wall thickness cylinder wall and the workpiece can be regarded as a whole (a straight simply supported beam 13), the fulcrums are the fixture seat and the cylinder cover respectively. When a uniformly distributed load q is applied to the straight simply supported beam 13 supported by two fulcrums, the deformation of the beam is The maximum deformation occurs in the middle of the beam. That is, the shape of the deflection curve 14. Therefore, the actual situation is that the contact surface between the cylinder wall and the thin-walled ring is large in the middle and gradually decreases toward the two ends. The friction between them is also reduced accordingly, which is not conducive to the clamping of the workpiece, and the tool will be let down during cutting, so the result after cutting is like Figure 4 Shown is a quartic concave curve.

[0020] But when the wall of the cylinder with equal wall thickness becomes a fish belly quartic curve shape, such as Figure 5 As shown, the cylinder 3 and the workpiece 11 are regarded as a whole (fish belly type quartic curve type simply supported beam 15), with the fulcrums of the fixture seat 2 and the cylinder cover 4 respectively. The beam can be regarded as a first-class strength beam. When a uniformly distributed load q is applied to it, the shape of the beam after deformation is the deflection curve 2 16. In actual conditions, since the wall thickness of the cylinder is larger than before, the overall deformation of the cylinder wall will be smaller, the inner wall bends outward to approximately a straight line, and the outer wall is slightly convex, which is similar to the wall of the same wall thickness. Therefore, the contact surface between the cylinder wall and the thin-walled ring is much larger than that of the same wall thickness fixture, and the friction between them is also increased, making it easier to clamp. As shown in the figure Figure 3 As shown, the outer circle of the workpiece turned by this fixture is relatively flat, with high parallelism and cylindricity, which greatly improves the processing accuracy and efficiency.

[0021] When the workpiece needs to be removed after cutting, the adjusting screw is turned outward, the liquid plastic space increases, and the pressure on the inner wall of the cubic curve cylinder will decrease until it disappears. The cylinder wall quickly returns to its original state and the processed workpiece is released at the same time. During the entire working process, since the cylinder body, the fixture seat and the cylinder cover are all welded, the liquid plastic may only flow out from the gap between the slider and the cylinder cover, but due to the presence of the sealing ring, the leakage will be greatly reduced, thereby ensuring the overall sealing.

Claims

1. A novel fixture for thin-walled external cylindrical turning, comprising a fixed chassis (1); characterized in that: A fixture seat (2) is connected to one side of the fixed chassis (1), and the fixture seat (2) is fastened to the fixed chassis (1) by a fixing screw (6). A cylinder (3) is connected to the top of the fixture seat (2), and a cylinder cover (4) is connected to the other end of the cylinder (3). The inner wall of the cylinder (3) is provided with a curved surface (7). Liquid plastic (8) is provided in the inner cavity of the cylinder (3). A threaded through hole is provided at the center of the cylinder cover (4). An adjusting screw (5) is provided in the threaded through hole. The top of the adjusting screw (5) is in a round head shape. The adjusting screw (5) contacts with a slider (9) inside the cylinder cover (4). A sealing ring (10) is provided between the slider (9) and the cylinder cover (4). The adjusting screw (5) pushes the slider (9) and the sealing ring (10) to slide synchronously, thereby compressing the volume of the liquid plastic (8). The workpiece (11) is sleeved on the outer surface of the cylinder (3) for cutting. The inner surface of the cylinder (3) is composed of two straight segments and a curved surface (7) which are smoothly connected. The two straight segments are respectively placed at two ends of the curved surface (7). Internal threads are arranged on the two straight segments. The curved surface segment (7) is a fish belly-shaped quartic surface. The slider (9) and the cylinder cover (4) are clearance-matched, a sealing groove is provided in the middle of the slider, a sealing ring (10) is provided in the sealing groove, and the slider (9) drives the sealing ring (10) to slide synchronously.

2. A new type of fixture for thin-walled external turning according to claim 1, characterized in that: The outer diameter of the boss on the clamp seat (2) is provided with a thread, the diameter of which is the same as the inner diameter of the lower end of the cylinder (3). The inner diameter of the upper end of the cylinder (3) is the same as the outer diameter of the cylinder cover (4). The outer diameter of the cylinder cover is also provided with a thread, and the connection between them is external welding and internal thread connection.

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