Bar clamping structure of machine tool

Abstract

The utility model provides a bar clamping structure of a machine tool, and belongs to the technical field of machine tool machining. The technical problem that existing bar clamping cannot guarantee concentricity with a main shaft and the like is solved. The machine tool comprises a shaft seat and a main shaft rotationally connected to the shaft seat, the main shaft is a hollow pipe, the bar clamping structure comprises two pneumatic chucks, rotary cylinders of the two pneumatic chucks are fixedly installed at the two ends of the main shaft respectively, shells of the pneumatic chucks are fixedly connected with the shaft seat, and the centers of the two pneumatic chucks are located on the axis of the main shaft. The utility model has the advantage of guaranteeing the concentricity of the bar and the main shaft.

Description

Technical Field

[0001] The utility model belongs to the technical field of machine tool processing and relates to a bar clamping structure of a machine tool. Background Technique

[0002] Bar processing has high requirements for accuracy. Especially when opening holes at the end of the bar, the opening accuracy directly affects the concentricity during bar splicing. For example, a billiard cue is composed of multiple sections of rods spliced together. The multiple sections are connected by bolts. When installing the bolts, it is required to be concentric with the billiard cue. If not concentric, the combined billiard cue of multiple sections will be bent, and the accuracy of hitting the ball cannot be guaranteed. Currently, the clamping of bars generally uses a chuck structure to achieve. For example, a chuck for cue processing disclosed in a Chinese patent document [Application No. 201520082767.3], a lathe chuck for billiard cues [Application No. 202221203423.X], etc. Such clamping structures are all for clamping and fixing the processing end of the bar. A large section of the rear part of the bar is in a suspended state during clamping. The suspended rear part of the bar during clamping will cause the whole bar to be stressed and inclined. After the chuck clamps and fixes, it cannot ensure the concentricity of the bar and the main shaft, resulting in insufficient subsequent processing accuracy. Summary of the Utility Model

[0003] The purpose of the utility model is to propose a bar clamping structure of a machine tool in view of the above problems existing in the prior art. The technical problem solved by the utility model is to ensure the concentricity of the bar and the main shaft.

[0004] The purpose of the utility model can be achieved by the following technical solutions:

[0005] A bar clamping structure of a machine tool. The machine tool includes a shaft seat and a main shaft rotatably connected to the shaft seat. It is characterized in that the main shaft is a hollow tube. The bar clamping structure includes two pneumatic chucks. The rotary cylinders of the two pneumatic chucks are respectively fixedly installed at both ends of the main shaft. The outer shell of the pneumatic chuck is fixedly connected to the shaft seat. The centers of the two pneumatic chucks are located on the axis of the main shaft.

[0006] During processing, the bar passes through the main shaft from one end to the other end. Both ends of the bar are respectively located in the two pneumatic chucks. The end of the bar to be processed extends out of the corresponding pneumatic chuck. The jaws of the two pneumatic chucks respectively clamp both ends of the bar. The main shaft drives the pneumatic chuck to rotate to realize the rotational processing of the bar. Both ends of the bar are clamped and centered by the two pneumatic chucks respectively. For a bar with a longer length, the concentricity of the bar and the main shaft can be ensured, and both ends of the bar are supported. The bar will not deform due to its own weight, thereby improving the processing accuracy of the processing end of the bar.

[0007] In the bar clamping structure of the above-mentioned machine tool, a central tube is also arranged inside the main shaft. Both ends of the central tube penetrate through the main shaft, and positioning bushings are detachably connected to both ends of the central tube respectively. The inner hole of the positioning bushing is a tapered hole, the inner hole of the positioning bushing is coaxial with the main shaft, and the end with a smaller inner diameter of the inner hole of the positioning bushing faces outward. The positioning bushings have different models, and the difference between different models of positioning bushings lies in the size of the inner diameter of the inner hole facing outward. The inner diameter of the inner hole of the positioning bushing facing outward is slightly larger than the diameter of the corresponding bar. During processing, the bar passes through the central tube, and the centers of both ends of the bar are close to the axis of the main shaft through the inner holes of the two positioning bushings facing outward, realizing the primary positioning of the bar and making it easier for the pneumatic chuck to clamp the bar.

[0008] In the bar clamping structure of the above-mentioned machine tool, the inner diameter of the inner hole of the positioning bushing facing inward is the same as the inner diameter of the central tube. This structure enables the inner wall of the inner hole of the positioning bushing to smoothly transition with the inner wall of the central tube, allowing the bar to smoothly pass through the central tube.

[0009] In the bar clamping structure of the above-mentioned machine tool, step grooves are provided on the inner sides of both ends of the central tube, the inner ends of the positioning bushings are clamped into the step grooves, and the outer ends of the positioning bushings are provided with outward-turned flange edges that can abut against the end faces of the central tube. The detachable connection between the positioning bushing and the central tube is realized through this structure.

[0010] In the bar clamping structure of the above-mentioned machine tool, the end face of the inner end of the positioning bushing abuts against the end face of the central tube, and connecting convex parts are provided on the outer walls of the inner end of the positioning bushing and the end of the central tube. The connecting convex parts of the positioning bushing and the central tube are fixed by bolts. The detachable connection between the positioning bushing and the central tube is realized through this structure.

[0011] In the bar clamping structure of the above-mentioned machine tool, a connecting ring part is provided at one end of the main shaft, a first flange is fixed to the outer end of the connecting ring part, a second flange is screwed to the other end of the main shaft, and the rotary cylinders of the two pneumatic chucks are respectively fixedly connected to the first flange and the second flange. The two pneumatic chucks are respectively installed at both ends of the main shaft through this structure.

[0012] In the bar clamping structure of the above-mentioned machine tool, a limiting rod is connected between the outer shells of the two pneumatic chucks, a limiting surface is provided on the shaft seat between the two pneumatic chucks, and the limiting rod abuts against the limiting surface. The outer shells of the two pneumatic chucks are circumferentially positioned through this structure, and the structure is simple.

[0013] In the bar clamping structure of the above-mentioned machine tool, an installation hole is provided on the shaft seat, the main shaft passes through the installation hole, two bearings are connected to the main shaft at intervals, both bearings are located in the installation hole, and oil seals are provided at both ends of the installation hole. The relative rotation of the main shaft with respect to the shaft seat is realized through this mechanism.

[0014] In the bar clamping structure of the above-mentioned machine tool, a driven pulley is further fixed on the main shaft, a main motor is fixed on the shaft seat, a main pulley is fixed on the motor shaft of the main motor, and the driven pulley and the main pulley are connected by a transmission belt. The main motor drives the main shaft to rotate through belt transmission.

[0015] In the bar clamping structure of the above-mentioned machine tool, the pneumatic chuck is a three-jaw pneumatic chuck.

[0016] Compared with the prior art, the bar clamping structure of this machine tool has the advantages of ensuring the concentricity of the bar and the main shaft, thereby improving the machining accuracy. Brief Description of the Drawings

[0017] Figure 1 is a schematic three-dimensional structure diagram of the bar clamping structure of this machine tool.

[0018] Figure 2 is a schematic three-dimensional structure diagram of the bar clamping structure.

[0019] Figure 3 is a schematic three-dimensional structure diagram of the assembly of the main shaft, bearings, flange one, and flange two.

[0020] Figure 4 is a schematic cross-sectional structure diagram when the main shaft and the center pipe are assembled.

[0021] In the figure, 1. pneumatic chuck; 2. shaft seat; 21. limit rod; 22. limit surface; 3. main shaft; 31. connecting ring part; 311. flange one; 32. flange two; 33. driven pulley; 331. transmission belt; 34. bearing; 35. oil seal; 4. center pipe; 41. step groove; 5. positioning bushing; 51. retaining edge. Detailed Description of the Invention

[0022] The following are specific embodiments of the present invention and in combination with the drawings, the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0023] Embodiment 1

[0024] As Figures 1 to 4 shown, the machine tool includes a shaft seat 2 and a main shaft 3 rotatably connected to the shaft seat 2. The main shaft 3 is a hollow tube. An installation hole is provided on the shaft seat 2. The main shaft 3 passes through the installation hole. Two bearings 34 are spacedly connected on the main shaft 3. Both of the two bearings 34 are located in the installation hole. Oil seals 35 are respectively fixed at both ends of the installation hole. A driven pulley 33 is further fixed on the main shaft 3. A main motor is fixed on the shaft seat 2. A main pulley is fixed on the motor shaft of the main motor. The driven pulley 33 and the main pulley are connected by a transmission belt 331.

[0025] The bar clamping structure includes two pneumatic chucks 1. The rotary cylinders of the two pneumatic chucks 1 are respectively fixedly installed at both ends of the main shaft 3. Specifically, one end of the main shaft 3 is provided with a connecting ring portion 31, and a first flange 311 is fixedly installed at the outer end of the connecting ring portion 31. A second flange 32 is screwed to the other end of the main shaft 3. The rotary cylinders of the two pneumatic chucks 1 are respectively fixedly connected to the first flange 311 and the second flange 32. A limiting rod 21 is connected between the outer shells of the two pneumatic chucks 1. A limiting surface 22 is provided on the shaft seat 2 between the two pneumatic chucks 1. The limiting rod 21 abuts against the limiting surface 22 so that the outer shell of the pneumatic chuck 1 is fixedly connected to the shaft seat 2. The centers of the two pneumatic chucks 1 are located on the axis of the main shaft 3. In this embodiment, the pneumatic chuck 1 is a three-jaw pneumatic chuck, which is an existing structure and the model is GXT-40 pneumatic chuck.

[0026] A central tube 4 is also inserted into the main shaft 3. Both ends of the central tube 4 respectively penetrate out of the main shaft 3. The central tube 4 is in a tight fit connection with the main shaft 3. Step grooves 41 are respectively opened on the inner sides of both ends of the central tube 4. The inner end of the positioning bushing 5 is clamped into the step groove 41. An outwardly turned flange 51 is provided at the outer end of the positioning bushing 5. The flange 51 can abut against the end face of the central tube 4 to realize the detachable connection between the positioning bushing 5 and the central tube 4. The inner hole of the positioning bushing 5 is a tapered hole. The inner hole of the positioning bushing 5 is coaxial with the main shaft 3. The end with a smaller inner diameter of the inner hole of the positioning bushing 5 faces outward. The inner diameter of the inner hole of the positioning bushing 5 facing inward is the same as the inner diameter of the central tube 4. In this embodiment, a section of bell mouth is provided at the outer end of the inner hole of the positioning bushing 5 at the feeding end of the main shaft 3. The end with a larger diameter of the bell mouth faces outward, and the section with a smaller diameter of the bell mouth is the end with a smaller inner diameter of the inner hole. The bell mouth can facilitate the bar to enter the positioning bushing 5. The positioning bushing 5 has different models. The difference between different models of the positioning bushing 5 lies in the size of the inner diameter of its outer-facing inner hole. The inner diameter of the outer-facing inner hole of the positioning bushing 5 is slightly larger than the diameter of the corresponding bar.

[0027] During processing, the bar is inserted from one end of the main shaft 3 to the other end of the main shaft 3. At this time, the bar is initially positioned by the positioning bushing 5. Both ends of the bar are respectively located in the two pneumatic chucks 1. The end of the bar to be processed extends out of the corresponding pneumatic chuck 1. The jaws of the two pneumatic chucks 1 respectively clamp both ends of the bar. The main shaft 3 drives the pneumatic chuck 1 to rotate to realize the rotational processing of the bar.

[0028] Embodiment Two

[0029] The structure and principle of this embodiment are basically the same as those of Embodiment One. The difference is that: the inner end face of the positioning bushing abuts against the end face of the central tube. Connecting protrusions are respectively provided on the outer wall of the inner end of the positioning bushing and the outer wall of the end of the central tube. The connecting protrusions of the positioning bushing and the connecting protrusions of the central tube are fixed by bolts. The detachable connection between the positioning bushing and the central tube is realized through this structure.

[0030] The specific embodiments described herein are merely illustrative of the spirit of the present utility model. Those skilled in the art to which the present utility model pertains may make various modifications or supplements to the described specific embodiments or use similar means for substitution, but will not deviate from the spirit of the present utility model or exceed the scope defined by the appended claims.

Claims

1. A bar clamping structure for a machine tool, the machine tool comprising an axle seat (2) and a spindle (3) rotatably connected to the axle seat (2), characterized in that: The spindle (3) is a hollow tube, and the bar clamping structure comprises two pneumatic chucks (1). The rotary cylinders of the two pneumatic chucks (1) are respectively fixedly mounted on the two ends of the spindle (3). The outer shell of the pneumatic chuck (1) is fixedly connected to the shaft seat (2), and the centers of the two pneumatic chucks (1) are located on the axis of the spindle (3).

2. The bar clamping structure of a machine tool according to claim 1, characterized in that: A center tube (4) is also provided inside the main shaft (3), and the two ends of the center tube (4) respectively extend out of the main shaft (3). The two ends of the center tube (4) are respectively detachably connected with positioning sleeves (5), and the inner hole of the positioning sleeve (5) is a tapered hole. The inner hole of the positioning sleeve (5) is coaxial with the main shaft (3), and the end of the inner hole of the positioning sleeve (5) with a smaller inner diameter is arranged outward.

3. The bar clamping structure of a machine tool according to claim 2, characterized in that: The inner diameter of the inner hole of the positioning bushing (5) is the same as the inner diameter of the center tube (4).

4. The bar clamping structure for a machine tool according to claim 2 or 3, characterized in that: Both ends of the center tube (4) are provided with step grooves (41) on the inner sides, the inner end of the positioning bushing (5) is inserted into the step groove (41), and the outer end of the positioning bushing (5) is provided with an outward-turned stop edge (51), and the stop edge (51) can abut against the end surface of the center tube (4).

5. The bar clamping structure for a machine tool according to claim 2 or 3, characterized in that: The inner end surface of the positioning bushing (5) is in contact with the end surface of the center tube (4), and the inner end outer wall of the positioning bushing (5) and the end outer wall of the center tube (4) are both provided with connecting protrusions, and the connecting protrusions of the positioning bushing (5) and the connecting protrusions of the center tube (4) are fixed by bolts.

6. The bar clamping structure for a machine tool according to claim 1, 2 or 3, characterized in that: A connecting ring portion (31) is provided at one end of the main shaft (3), a flange plate 1 (311) is fixed to the outer end of the connecting ring portion (31), a flange plate 2 (32) is screwed to the other end of the main shaft (3), and the rotary cylinders of the two pneumatic chucks (1) are fixedly connected to the flange plate 1 (311) and the flange plate 2 (32) respectively.

7. The bar clamping structure for a machine tool according to claim 1, 2 or 3, characterized in that: A limiting rod (21) is connected between the shells of the two pneumatic chucks (1), a limiting surface (22) is provided on the shaft seat (2) between the two pneumatic chucks (1), and the limiting rod (21) is in contact with the limiting surface (22).

8. The bar clamping structure for a machine tool according to claim 1, 2 or 3, characterized in that: The shaft seat (2) is provided with a mounting hole, the main shaft (3) passes through the mounting hole, two bearings (34) are connected to the main shaft (3) at intervals, the two bearings (34) are both located in the mounting hole, and oil seals (35) are respectively provided at both ends of the mounting hole.

9. The bar clamping structure for a machine tool according to claim 1, 2 or 3, characterized in that: A slave pulley (33) is also fixed on the main shaft (3), a main motor is fixed on the shaft seat (2), a main pulley is fixed on the motor shaft of the main motor, and the slave pulley (33) and the main pulley are connected via a transmission belt (331).

10. The bar clamping structure for a machine tool according to claim 1, 2 or 3, characterized in that: The pneumatic chuck (1) is a three-jaw pneumatic chuck (1).

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