Large aperture numerical control pipe thread lathe spindle hole roller centering device and method

Abstract

This invention discloses a centering device for the spindle bore of a large-diameter CNC pipe threading lathe. The device comprises an annular support body and multiple roller supports, each containing a bearing. The roller supports are connected to the annular support body by fixing screws. Each roller support is concave in shape. One end of the annular support body has a boss that matches the roller support. A steel pipe passes through the annular channel formed by the multiple roller supports. This invention also discloses a method for centering the spindle bore of a large-diameter CNC pipe threading lathe. The centering device and method disclosed in this invention solve the problem in existing technologies where, during the centering process, the center of gravity of the steel pipe is forward, causing excessive pressure on the rear chuck jaws and resulting in chuck jaw wear.

Description

Technical Field

[0001] This invention belongs to the technical field of mechanical manufacturing and processing equipment, specifically a centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe, and also relates to a method for centering the spindle bore roller of a large-diameter CNC pipe threading lathe. Background Technology

[0002] Large-diameter CNC pipe threading lathes have a three-jaw chuck at each end of the spindle for clamping long steel pipes, primarily used for turning pipes longer than 2 meters. Due to the length of the steel pipes, traditional CNC pipe threading lathes face difficulties in loading during clamping. During clamping, the steel pipe's center of gravity is forward, with the fulcrum located on the rear chuck jaws, making centering and movement difficult, significantly increasing operational complexity, time commitment, and hindering the full utilization of CNC machine tools, resulting in low production efficiency. Specifically, in the loading stage, the large weight and length of the steel pipes, far exceeding that of conventionally machined parts, require workers to expend considerable physical strength and energy to move and place them. This not only results in extremely high labor intensity but also increases the risk of damage due to improper operation, increasing production costs and scrap rates. Furthermore, the forward center of gravity of the steel pipe during clamping places immense pressure on the rear chuck jaws, easily causing premature wear, reducing chuck lifespan, and leading to decreased clamping accuracy.

[0003] During the centering process, due to the lack of effective auxiliary support and precise positioning devices, achieving accurate centering of a long steel pipe between the front and rear chucks requires an extremely high level of skill from the operator. Even experienced workers often need to make multiple adjustments to achieve a relatively satisfactory result, which undoubtedly further prolongs the clamping time. Furthermore, moving the steel pipe is extremely difficult due to its length and weight, making rapid and accurate position adjustments impossible and rendering the clamping operation exceptionally cumbersome and complex. This situation severely restricts the high efficiency and high precision advantages of CNC machine tools, causing turning tasks that could have been completed quickly and accurately to become inefficient due to problems in the clamping process. Moreover, prolonged auxiliary operations increase equipment downtime and reduce equipment utilization. Summary of the Invention

[0004] The primary objective of this invention is to provide a centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe, thereby solving the problem in the prior art where, during the centering process, the center of gravity of the steel pipe is forward, causing the rear chuck jaws to bear greater pressure and resulting in wear of the chuck jaws.

[0005] The second objective of this invention is to provide a method for centering the spindle bore rollers of a large-diameter CNC pipe threading lathe.

[0006] The first technical solution adopted in this invention is a centering device for the spindle bore rollers of a large-diameter CNC pipe threading lathe, comprising an annular support body and multiple roller frames. Each roller frame is equipped with a bearing. The multiple roller frames are respectively connected to the annular support body by fixing screws. Each roller frame is concave in shape. A boss matching the roller frame is opened at one end of the annular support body. A steel pipe is inserted in the annular channel formed by the multiple roller frames.

[0007] The first technical solution of the present invention is further characterized in that, Each roller carrier includes a roller bearing, a cylindrical pin, and an adjustable shim. The roller bearing is mounted on the roller carrier, with the inner ring of the roller bearing and the cylindrical pin having an interference fit. An adjustable shim is installed between the outer ring of the roller bearing and the roller carrier.

[0008] The adjustable shim thickness is 0.1-0.5mm.

[0009] Rollers are fitted onto the roller bearings, and the steel pipe abuts against the rollers.

[0010] The ring support body adopts a tapered surface structure that matches the spindle hole of a large-diameter CNC pipe thread lathe.

[0011] The ring bracket body is connected to the spindle hole of a large-diameter CNC pipe thread lathe by set screws.

[0012] Multiple roller frames are evenly distributed and installed on the ring-shaped support body at 60° intervals along the circumference.

[0013] The second technical solution adopted in this invention is a method for centering the spindle bore of a large-diameter CNC pipe threading lathe using a roller centering device, specifically implemented according to the following steps: The annular support body is slowly pushed in along the axis of the thread lathe spindle hole, so that the conical surface of the annular support body is completely in contact with the spindle hole; the steel pipe is rolled and pressed by the roller frame and then sent into the thread lathe spindle hole, so that the axis of the steel pipe is coaxial with the thread lathe spindle, and then pushed into the thread lathe to complete the centering.

[0014] Compared with the prior art, the beneficial effects of the present invention are: (1) The large-diameter CNC pipe threading lathe spindle hole centering device and method provided by the present invention can ensure the stable clamping of steel pipes when the spindle rotates to any direction, and solves the problem of clamping difficulties caused by short clamping and loosening strokes of the chucks and long spindle length.

[0015] (2) The spindle hole centering device and method for large-diameter CNC pipe threading lathe provided by the present invention makes the center of gravity distribution of the steel pipe more reasonable and reduces the pressure on the rear chuck jaws. This can not only extend the service life of the chuck and reduce equipment maintenance costs, but also ensure clamping accuracy and improve the quality of turning.

[0016] (3) The spindle hole centering device and method for large-diameter CNC pipe threading lathe provided by this invention solves the clamping problem, allowing the high efficiency and high precision characteristics of CNC machine tools to be fully utilized. It reduces the time consumed in the clamping process, enabling the equipment to be more fully engaged in turning operations and improving equipment utilization. Machining tasks that were previously inefficient due to clamping problems can be completed in a shorter time, significantly improving production efficiency. Attached Figure Description Figure 1 This is a schematic diagram of the structure of the spindle bore centering device for a large-diameter CNC pipe threading lathe according to the present invention; Figure 2 This is a side view schematic diagram of the spindle hole centering device of the large-diameter CNC pipe threading lathe of the present invention; Figure 3 This is an isometric view of the spindle bore roller centering device for the large-diameter CNC pipe threading lathe of the present invention; Figure 4 This is a schematic diagram of the roller centering device used in the CNC lathe in Embodiment 5 of the present invention; Figure 5 This is a schematic diagram illustrating the effect of the roller centering device in Embodiment 5 of the present invention.

[0017] In the figure, 1. Roller frame, 2. Bearing, 3. Cylindrical pin, 4. Adjustable shim, 5. Fixing screw, 6. Set screw, 7. Ring bracket body, 8. Steel pipe, 9. Threading lathe, 10. Front chuck, 11. Rear chuck, 12. Spindle through hole, 13. Roller centering device. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0019] This invention provides a centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe, such as... Figure 1-3As shown, the system includes an annular support body 7 and multiple roller frames 1. Each roller frame 1 has a bearing 2 installed inside. The multiple roller frames 1 are connected to the annular support body 7 by fixing screws 5. Each roller frame 1 is concave in shape. One end of the annular support body 7 has a boss that matches the roller frame 1. A steel pipe 8 passes through the annular channel formed by the multiple roller frames 1. Each roller frame 1 includes a roller bearing 2, a cylindrical pin 3, and an adjustable shim 4. The roller bearing 2 is installed on the roller frame 1. The inner ring of the roller bearing 2... An adjustable shim 4 is installed between the outer ring of the roller bearing 2 and the roller carrier 1, with an interference fit with the cylindrical pin 3; the thickness of the adjustable shim 4 is 0.1-0.5mm; a roller is fitted on the roller bearing 2, and the steel pipe 8 abuts against the roller; the annular bracket body 7 adopts a tapered surface structure that matches the spindle hole of the large-diameter CNC pipe thread lathe; the annular bracket body 7 is connected to the spindle hole of the large-diameter CNC pipe thread lathe by a set screw 6; multiple roller carriers 1 are evenly distributed on the annular bracket body 7 at 60° intervals along the circumference.

[0020] The present invention also provides a method for centering the spindle bore of a large-diameter CNC pipe threading lathe using rollers. The method uses the aforementioned roller centering device for the spindle bore of a large-diameter CNC pipe threading lathe. The specific steps are as follows: the annular support body 7 is slowly pushed in along the axis of the spindle bore of the threading lathe, so that the conical surface of the annular support body 7 is completely in contact with the spindle bore; the steel pipe 8 is rolled and pressed by the roller frame 1 and then fed into the spindle bore of the threading lathe, so that the axis of the steel pipe is coaxial with the spindle of the threading lathe, and then pushed into the threading lathe to complete the centering.

[0021] Example 1 The present invention provides a centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe, such as... Figure 1 , Figure 2 and Figure 3 As shown, it includes an annular support body 7 and multiple roller frames 1. Each roller frame 1 is equipped with a bearing 2. The multiple roller frames 1 are connected to the annular support body 7 by fixing screws 5. Each roller frame 1 is concave. One end of the annular support body 7 has a boss that matches the roller frame 1. A steel pipe 8 is inserted in the annular channel formed by the multiple roller frames 1.

[0022] Furthermore, the ring bracket body 7 is made of high-strength aluminum alloy or cast iron, and the inner wall is designed as a conical structure that fits tightly with the lathe spindle hole. Radial pre-tightening is achieved by 12 evenly distributed set screws 6 to ensure that the coaxiality error between the device and the spindle hole is ≤0.02mm.

[0023] The large-diameter CNC pipe threading lathe spindle bore centering device provided by this invention operates on the following principle: When the steel pipe 8 enters the spindle bore, six sets of rollers achieve three-point contact centering through the free rotation of the bearing 2. The uniform distribution of the rollers forms a stable support surface, automatically correcting the coaxiality between the steel pipe axis and the spindle (coaxiality error ≤ 0.05mm). The tapered structure of the support body 7 mates with the spindle bore, eliminating radial runout during rotation. Combined with the elastic preload of the set screw 6, this ensures the stability of the device at high-speed rotation up to 3000 rpm.

[0024] Example 2 The present invention provides a centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe, such as... Figure 1 , Figure 2 and Figure 3 As shown, it includes an annular support body 7 and multiple roller frames 1. Each roller frame 1 is equipped with a bearing 2. The multiple roller frames 1 are connected to the annular support body 7 by fixing screws 5. Each roller frame 1 is concave. One end of the annular support body 7 has a boss that matches the roller frame 1. A steel pipe 8 is inserted in the annular channel formed by the multiple roller frames 1.

[0025] Furthermore, the ring bracket body 7 is made of high-strength aluminum alloy or cast iron, and the inner wall is designed as a conical structure that fits tightly with the lathe spindle hole. Radial pre-tightening is achieved by 12 evenly distributed set screws 6 to ensure that the coaxiality error between the device and the spindle hole is ≤0.02mm.

[0026] Furthermore, the six sets of roller frames 1 are installed at a 60° angle.

[0027] Example 3 This embodiment provides a centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe provided by this invention is as follows: Figure 1 , Figure 2 and Figure 3 As shown, the system includes an annular support body 7 and multiple roller frames 1. Each roller frame 1 has a bearing 2 installed inside. The multiple roller frames 1 are connected to the annular support body 7 by fixing screws 5. Each roller frame 1 is concave in shape. One end of the annular support body 7 has a boss that matches the roller frame 1. A steel pipe 8 passes through the annular channel formed by the multiple roller frames 1. Each roller frame 1 includes a roller bearing 2, a cylindrical pin 3, and an adjustable shim 4. The roller bearing 2 is installed on the roller frame 1. The inner ring of the roller bearing 2 is interference-fitted with the cylindrical pin 3. The adjustable shim 4 is installed between the outer ring of the roller bearing 2 and the roller frame 1.

[0028] Furthermore, each set of roller frames 1 includes roller bearings 2, which can withstand radial and axial loads; cylindrical pins 3 with a diameter of 12mm are press-fitted with roller frames 1; adjustable shims 4 (thickness 0.1-0.5mm) are used to compensate for bearing wear.

[0029] Example 4 This embodiment provides a centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe provided by this invention is as follows: Figure 1 , Figure 2 and Figure 3 As shown, the system includes an annular support body 7 and multiple roller frames 1. Each roller frame 1 has a bearing 2 installed inside. The multiple roller frames 1 are connected to the annular support body 7 by fixing screws 5. Each roller frame 1 is concave in shape. One end of the annular support body 7 has a boss that matches the roller frame 1. A steel pipe 8 passes through the annular channel formed by the multiple roller frames 1. Each roller frame 1 includes a roller bearing 2, a cylindrical pin 3, and an adjustable shim 4. The roller bearing 2 is installed on the roller frame 1. The inner ring of the roller bearing 2 is interference-fitted with the cylindrical pin 3. An adjustable shim 4 is installed between the outer ring of the roller bearing 2 and the roller frame 1. A roller is fitted on the roller bearing 2, and the steel pipe 8 abuts against the roller.

[0030] Furthermore, each roller frame 1 includes roller bearings 2, capable of withstanding radial and axial loads; cylindrical pins 3, with a diameter of 12mm, are interference-fitted with the roller frame 1; adjustable shims 4 (thickness 0.1-0.5mm) are used to compensate for bearing wear. The rollers are made of GCr15 hardened steel (hardness HRC60-62), with a surface roughness Ra≤0.8μm, and the working outer diameter is designed to accommodate steel pipes of φ100-φ300mm. By replacing shims 4 of different thicknesses (in 0.1mm increments), the radial position of the roller assembly can be adjusted to accommodate steel pipe diameter variations of ±2mm. The roller bearings 2 employ a pre-lubricated sealing design; when the steel pipe is subjected to an off-center load exceeding 15kN, the bearing clearance is automatically compensated to prevent jamming.

[0031] Example 5 This embodiment provides a centering device and installation method for the spindle bore roller of a large-diameter CNC pipe threading lathe. The centering device for the spindle bore of a large-diameter CNC pipe threading lathe provided by this invention is as follows: Figure 1 , Figure 2 and Figure 3As shown, the system includes an annular support body 7 and multiple roller frames 1. Each roller frame 1 contains a bearing 2. The multiple roller frames 1 are connected to the annular support body 7 by fixing screws 5. Each roller frame 1 is concave in shape. One end of the annular support body 7 has a boss that matches the roller frame 1. A steel pipe 8 passes through the annular channel formed by the multiple roller frames 1. Each roller frame 1 includes a roller bearing 2, a cylindrical pin 3, and an adjustable shim 4. The roller bearing 2 is mounted on the roller frame 1. The inner ring of the roller bearing 2 is interference-fitted with the cylindrical pin 3. The adjustable shim 4 is installed between the outer ring of the roller bearing 2 and the roller frame 1. A roller is fitted on the roller bearing 2, and the steel pipe 8 abuts against the roller.

[0032] Furthermore, each roller frame 1 includes roller bearings 2, capable of withstanding radial and axial loads; cylindrical pins 3, with a diameter of 12mm, are interference-fitted with the roller frame 1; adjustable shims 4 (thickness 0.1-0.5mm) are used to compensate for bearing wear. The rollers are made of GCr15 hardened steel (hardness HRC60-62), with a surface roughness Ra≤0.8μm, and the working outer diameter is designed to accommodate steel pipes of φ100-φ300mm. By replacing shims 4 of different thicknesses (in 0.1mm increments), the radial position of the roller assembly can be adjusted to accommodate steel pipe diameter variations of ±2mm. The roller bearings 2 employ a pre-lubricated sealing design; when the steel pipe is subjected to an off-center load exceeding 15kN, the bearing clearance is automatically compensated to prevent jamming.

[0033] The installation method and specific steps for the centering device of the spindle bore roller on a large-diameter CNC pipe threading lathe are as follows: S1. Clean the inner surface of the spindle hole 12 and check the thread condition of the set screw 6 to ensure there is no rust or damage; S2. Slowly push the bracket body 7 in along the axis of the main shaft hole until the conical surface is completely in contact with the main shaft hole; S3. Using a torque wrench, tighten the 12 set screws 6 gradually in a diagonal sequence, with the final torque controlled at 80-100 N·m; S4. Manually rotate roller frame 1 to confirm there is no jamming; use a dial indicator to check the radial runout of bracket body 7 (requirement ≤0.03mm).

[0034] Example 6 This embodiment provides a centering device and method for the spindle bore roller of a large-diameter CNC pipe threading lathe. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe provided by this invention is as follows: Figure 1 , Figure 2 and Figure 3As shown, the system includes an annular support body 7 and multiple roller frames 1. Each roller frame 1 has a bearing 2 installed inside. The multiple roller frames 1 are connected to the annular support body 7 by fixing screws 5. Each roller frame 1 is concave in shape. One end of the annular support body 7 has a boss that matches the roller frame 1. A steel pipe 8 passes through the annular channel formed by the multiple roller frames 1. Each roller frame 1 includes a roller bearing 2, a cylindrical pin 3, and an adjustable shim 4. The roller bearing 2 is installed on the roller frame 1. The inner ring of the roller bearing 2 is interference-fitted with the cylindrical pin 3. An adjustable shim 4 is installed between the outer ring of the roller bearing 2 and the roller frame 1. A roller is fitted on the roller bearing 2.

[0035] Furthermore, each roller frame 1 includes roller bearings 2, capable of withstanding radial and axial loads; cylindrical pins 3, with a diameter of 12mm, are interference-fitted with the roller frame 1; adjustable shims 4 (thickness 0.1-0.5mm) are used to compensate for bearing wear. The rollers are made of GCr15 hardened steel (hardness HRC60-62), with a surface roughness Ra≤0.8μm, and the working outer diameter is designed to accommodate steel pipes of φ100-φ300mm. By replacing shims 4 of different thicknesses (in 0.1mm increments), the radial position of the roller assembly can be adjusted to accommodate steel pipe diameter variations of ±2mm. The roller bearings 2 employ a pre-lubricated sealing design; when the steel pipe is subjected to an off-center load exceeding 15kN, the bearing clearance is automatically compensated to prevent jamming.

[0036] like Figure 4 and Figure 5 As shown, the specific steps of the centering method for the spindle bore roller of a large-diameter CNC pipe threading lathe are as follows: Step 1: Initially center the rear end of the steel pipe 8 through the rear chuck 11, and align the front end with the spindle hole 3 12; Step 2: Start the pushing mechanism of the chuck 2 to make the steel pipe 8 pass through the roller centering device 13. At this time, the roller group automatically corrects the axis of the steel pipe. Step 3: Front chuck 1 clamps the front end of the steel pipe, and rear chuck 2 releases and returns to its initial position.

[0037] More specifically, when machining long steel pipes on a large-diameter CNC pipe threading lathe, there is a difficulty in inserting the steel pipe into the rear chuck. The current method uses a set of rollers outside the rear chuck in conjunction with a pneumatic upper clamping wheel to roll and clamp the long steel pipe, keeping it horizontal, before manually pushing it into the lathe spindle for clamping and machining. Furthermore, when changing to steel pipes of different diameters, only the thickness of the shim needs to be adjusted; disassembly of the device is unnecessary.

Claims

1. A centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe, characterized in that, It includes an annular support body (7) and multiple roller frames (1). Each roller frame (1) is equipped with a bearing (2). The multiple roller frames (1) are connected to the annular support body (7) by fixing screws (5). Each roller frame (1) is concave. One end of the annular support body (7) has a boss that matches the roller frame (1). A steel pipe (8) is inserted in the annular channel formed by the multiple roller frames (1).

2. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe according to claim 1, characterized in that, Each of the roller frames (1) includes a roller bearing (2), a cylindrical pin (3) and an adjustable shim (4). The roller bearing (2) is mounted on the roller frame (1). The inner ring of the roller bearing (2) is interference-fitted with the cylindrical pin (3). The adjustable shim (4) is installed between the outer ring of the roller bearing (2) and the roller frame (1).

3. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe according to claim 2, characterized in that, The thickness of the adjustable pad (4) is 0.1-0.5 mm.

4. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe according to claim 2, characterized in that, The roller bearing (2) is fitted with a roller, and the steel pipe (8) abuts against the roller.

5. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe according to claim 1, characterized in that, The annular support body (7) adopts a conical surface structure that matches the spindle hole of a large-diameter CNC pipe thread lathe.

6. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe according to claim 5, characterized in that, The annular bracket body (7) is connected to the spindle hole of a large-diameter CNC pipe thread lathe by a set screw (6).

7. The centering device for the spindle bore roller of a large-diameter CNC pipe threading lathe according to claim 1, characterized in that, Multiple roller frames (1) are evenly distributed and installed on the annular support body (7) at 60° intervals along the circumferential direction.

8. A method for centering the spindle bore roller of a large-diameter CNC pipe threading lathe, characterized in that, Using the large-diameter CNC pipe threading lathe spindle hole roller centering device as described in any one of claims 1-7, the specific steps are as follows: slowly push the annular bracket body (7) along the axis of the threading lathe spindle hole so that the conical surface of the annular bracket body (7) is completely in contact with the spindle hole; after rolling and pressing the steel pipe (8) through the roller frame (1), send it into the threading lathe spindle hole so that the axis of the steel pipe is coaxial with the threading lathe spindle, push it into the threading lathe, and complete the centering.

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