Compensation device for thermal errors of a machine tool feed axis screw

Abstract

This invention provides a compensation device for thermal error of a machine tool feed axis leadscrew, comprising a first tail end spacer and several bearings sequentially fitted onto the tail end of the leadscrew. The tail end of the leadscrew has a positioning step. The inner ring of the bearing is in close contact with the first tail end spacer, and the first tail end spacer is in close contact with the positioning step. The device also includes a pressure cap, a disc spring, a fixed seat, a ejector pin, and a displacement sensor. The pressure cap and disc spring are both fitted onto the first tail end spacer. The fixed seat is fixed to the machine frame, and the pressure cap is fixed to the fixed seat. The two ends of the disc spring respectively abut against the pressure cap and the outer ring of the bearing. The displacement sensor is fixed to the fixed seat, and the ejector pin is slidably disposed within the fixed seat. The two ends of the ejector pin are in close contact with the outer ring of the bearing and the end of the displacement sensor, respectively. This machine tool feed axis leadscrew thermal error compensation device ensures the integrity of the bearing's rightward movement through the release of the disc spring's elastic force, resulting in small errors, improved compensation effect, and improved accuracy of the machine tool during actual operation.

Description

Technical Field

[0001] This invention belongs to the field of machine tool equipment technology and relates to a compensation device for thermal error of the feed axis lead screw of a machine tool. Background Technology

[0002] When a machine tool is working, the machine tool control system needs to calculate the position coordinates of the spindle bottom center and the worktable at every moment. For machine tools driven by lead screws and nuts, the X-axis slide, Y-axis slide, and Z-axis spindle box are all fixed to the nut. The servo motor drives the lead screw to rotate and push the nut. The nut drives the X-axis slide, Y-axis slide, and Z-axis spindle box to move. The servo motor records the number of rotations of the corresponding lead screw at each moment and sends the value of the number of rotations to the machine tool control system. The machine tool control system can accurately calculate the position coordinates of the X-axis slide, Y-axis slide, and Z-axis spindle box according to the lead screw pitch and initial coordinate information. The initial coordinate information of each axis slide of the lathe is set after the lathe is completed. After that, the machine tool control system can determine the position coordinates of the worktable and the spindle bottom center according to the number of rotations of the lead screw. When a machine tool is working, the lead screw and nut drive the axis slide, generating a large amount of frictional heat. This causes a temperature difference between the lead screw and the axis slide / or axis seat, leading to thermal expansion and contraction of the lead screw. This alters its effective length and pitch, reducing the positioning accuracy of the feed motion. Consequently, the coordinate values ​​of the worktable and spindle bottom center positions calculated by the machine tool control system deviate, resulting in errors in the dimensions of the machined workpiece due to the thermal expansion of the lead screw, thus reducing the accuracy of the machine tool during actual operation. Existing technologies employ some compensation devices to compensate for machine tool defects, but the compensation effect is unsatisfactory. Current technologies often use screw-shaped temperature sensors or magnetic sensors that need to be attached to the machine tool surface. However, the lead screw is constantly in motion during machine operation, making it impossible to measure the temperature of the lead screw during movement. This significantly reduces the compensation effect, making it difficult to substantially improve machine tool accuracy. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned problems in the prior art by providing a compensation device for thermal errors in the feed axis leadscrew of a machine tool with small errors.

[0004] The objective of this invention can be achieved through the following technical solution: a compensation device for thermal error of a machine tool feed axis lead screw, comprising a first tail end spacer and several bearings sequentially sleeved on the tail end of the lead screw, the tail end of the lead screw having a positioning step, the inner ring of the bearing being in close contact with the first tail end spacer, the first tail end spacer being in close contact with the positioning step, and further comprising a pressure cap, a disc spring, a fixed seat, a ejector pin, and a displacement sensor, wherein the pressure cap and the disc spring are both sleeved on the first tail end spacer, the fixed seat is fixed on the machine frame, the pressure cap is fixed on the fixed seat, the two ends of the disc spring respectively abut against the pressure cap and the outer ring of the bearing, the displacement sensor is fixed on the fixed seat, the ejector pin is slidably disposed in the fixed seat, and the two ends of the ejector pin are respectively in close contact with the outer ring of the bearing and the end of the displacement sensor;

[0005] In the aforementioned compensation device for thermal error of the machine tool feed axis lead screw, when the lead screw expands and elongates due to heat, the positioning step causes the first tail end spacer to move to the right, and the first tail end spacer causes the inner ring of the bearing to move to the right. At this time, the inner ring of the bearing is misaligned with the outer ring, and the outer ring of the bearing has space to move to the right. The release of the spring force causes the outer ring of the bearing to move to the right until the outer ring of the bearing is in close contact with the balls inside the bearing, and the balls are in close contact with the inner ring of the bearing, thus making the bearing fit together. The rightward movement of the outer ring of the bearing is equal to the rightward movement of the inner ring of the bearing, which is equal to the thermal expansion elongation of the lead screw. The outer ring of the bearing causes the ejector pin to move to the right, and the rightward movement of the ejector pin is accurately measured by the displacement sensor.

[0006] The aforementioned compensation device for thermal error of the machine tool feed axis lead screw further includes a second tail end spacer and a locking nut fitted at the tail of the lead screw. The tail of the lead screw is provided with a locking thread, and the locking nut is installed on the locking thread. Tightening the locking nut makes the locking nut fit tightly against the second tail end spacer. The second tail end spacer fits tightly against the inner ring of the bearing. The first tail end spacer sequentially drives the inner ring of the bearing, the second tail end spacer, and the locking nut to move to the right.

[0007] In the aforementioned compensation device for thermal error of the machine tool feed axis lead screw, the end of the first tail end spacer is provided with a spacer flange, the pressure cover is provided with a movable groove, the spacer flange is located in the movable groove, the groove wall of the movable groove is provided with a limiting protrusion, there is a first movable space between the side of the spacer flange away from the positioning step and the end face of the limiting protrusion, and the width of the first movable space is greater than the maximum thermal expansion elongation of the lead screw.

[0008] In the aforementioned compensation device for thermal error of the machine tool feed axis lead screw, a movable guide groove is provided below the limiting protrusion, and a protruding guide block is formed on the first tail end spacer. The guide block is movably located in the movable guide groove, and there is a second movable space between the side of the guide block and the groove wall of the movable guide groove. The width of the second movable space is greater than the maximum thermal expansion elongation of the lead screw. The limiting protrusion, the movable guide groove, and the guide block form a labyrinth within the movable groove.

[0009] In the aforementioned compensation device for thermal error of the machine tool feed axis lead screw, a flange groove is formed on the spacer flange, and the groove wall of the flange groove near the positioning step is a guide slope.

[0010] Compared with existing technologies, the thermal error compensation device for the feed axis lead screw of this machine tool ensures the integrity of the bearing's rightward movement through the release of the disc spring's elasticity. This prevents errors between the rightward movement of the ejector pin and the thermal expansion elongation of the lead screw caused by gaps within the bearing, ensuring that the bearing as a whole produces the same displacement. It also ensures that the thermal expansion elongation of the lead screw is accurately measured by the displacement sensor, resulting in minimal error, improved compensation effect, and enhanced machine tool accuracy during actual operation. The guide bevel acts as a guide for dust and impurities entering the movable groove, directing them into the flange groove, which forms an initial dust settling area. The limiting protrusion, moving guide groove, and guide block create a labyrinth within the movable groove, further hindering dust movement and preventing dust from entering the disc spring and bearing through the movable groove, the gap between the gland and the first tail end spacer, causing contamination and affecting service life. Attached Figure Description

[0011] Figure 1 This is a three-dimensional structural diagram of the compensation device for thermal error of the feed axis lead screw of this machine tool.

[0012] Figure 2 This is a cross-sectional schematic diagram of the compensation device for thermal error of the feed axis lead screw of this machine tool.

[0013] Figure 3 yes Figure 2 A magnified structural diagram of point A in the middle.

[0014] Figure 4 yes Figure 3 A magnified structural diagram at point B in the middle.

[0015] In the diagram, 1. Lead screw; 11. Positioning step; 2. First tail end spacer; 21. Spacer flange; 22. Guide block; 23. Flange groove; 24. Guide slope; 3. Pressure cap; 31. Movable groove; 32. Limiting protrusion; 33. Moving guide groove; 4. Disc spring; 5. Second tail end spacer; 6. Locking nut; 7. Bearing; 71. Inner ring; 72. Outer ring; 73. Ball bearing; 8. Fixed seat; 9. Ejector pin; 10. Displacement sensor. Detailed Implementation

[0016] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0017] like Figure 1-4 As shown, the compensation device for thermal error of the feed axis lead screw of this machine tool includes a first tail end spacer 2, several bearings 7, a second tail end spacer 5, and a locking nut 6, which are sequentially fitted onto the tail of the lead screw 1. The tail end of the lead screw 1 is provided with a positioning step 11 and a locking thread. The locking nut 6 is installed on the locking thread. Tightening the locking nut 6 makes the locking nut 6 fit tightly against the second tail end spacer 5. The second tail end spacer 5 fits tightly against the inner ring 71 of the bearing 7. The inner ring 71 of the bearing 7 fits tightly against the first tail end spacer 2. The first tail end spacer 2 fits tightly against the positioning step 11. It also includes a pressure cover 3, a disc spring 4, a fixed seat 8, a ejector pin 9, and a displacement sensor 10. The pressure cover 3 and the disc spring 4 are both fitted onto the first tail end spacer 2. The fixed seat 8 is fixed to the machine frame. The pressure cover 3 is fixed to the fixed seat 8. The two ends of the disc spring 4 abut against the pressure cover 3 and the outer ring 72 of the bearing 7, respectively. The displacement sensor 10 is fixed on the fixed base 8, and the ejector pin 9 is slidably disposed in the fixed base 8. The two ends of the ejector pin 9 are respectively in close contact with the outer ring 72 of the bearing 7 and the end of the displacement sensor 10.

[0018] When the lead screw 1 expands and elongates due to heat, the positioning step 11 causes the first tail end spacer 2 to move to the right. The first tail end spacer 2 then sequentially causes the inner ring 71 of the bearing 7, the second tail end spacer 5, and the locking nut 6 to move to the right. At this time, the inner ring 71 and the outer ring 72 of the bearing 7 are misaligned, and the outer ring 72 of the bearing 7 has space to move to the right. The release of the spring force of the disc spring 4 causes the outer ring 72 of the bearing 7 to move to the right until the outer ring 72 of the bearing 7 is in close contact with the ball 73 inside the bearing 7, and the ball 73 is in close contact with the inner ring 71 of the bearing 7, thus making the bearing 7 fit together. The rightward movement of the outer ring 72 of the bearing 7 is equal to the rightward movement of the inner ring 71 of the bearing 7, which is equal to the thermal expansion elongation of the lead screw 1. The outer ring 72 of the bearing 7 causes the ejector pin 9 to move to the right. The rightward movement of the ejector pin 9 is accurately measured by the displacement sensor 10, that is, the thermal expansion elongation of the lead screw 1 is accurately measured by the displacement sensor 10. The lead screw, which is 1 meter long, elongates by about 1 mil for every degree of increase.

[0019] In the above technical solution: the end of the first tail-end spacer 2 is provided with a spacer flange 21, and the pressure cap 3 is provided with a movable groove 31. The spacer flange 21 is located in the movable groove 31, and a limiting protrusion 32 is provided on the groove wall of the movable groove 31. There is a first movable space between the side of the spacer flange 21 away from the positioning step 11 and the end face of the limiting protrusion 32. The width of the first movable space is much larger than the maximum possible thermal expansion elongation of the lead screw.

[0020] In the above technical solution: a movable guide groove 33 is provided below the limiting protrusion 32, and a protruding guide block 22 is formed on the first tail end spacer 2. The guide block 22 is movably located within the movable guide groove 33, and a second movable space exists between the side of the guide block 22 and the groove wall of the movable guide groove 33. The width of the second movable space is much larger than the maximum possible thermal expansion elongation of the lead screw.

[0021] In the above technical solution: a flange groove 23 is formed on the spacer flange 21. The groove wall of the flange groove 23 near the positioning step 11 is a guide slope 24. The guide slope 24 guides the dust and impurities entering the movable groove 31, causing the dust and impurities to enter the flange groove 23, forming a preliminary dust settling area. The limiting protrusion 32, the moving guide groove 33, and the guide block 22 form a labyrinth in the movable groove 31. The labyrinth further blocks the movement of dust, preventing dust from entering the disc spring 4 and bearing 7 through the movable groove 31 and the gap between the pressure cover 3 and the first tail end spacer 2, causing contamination and affecting service life.

[0022] The thermal error compensation device for the feed axis lead screw of this machine tool ensures the integrity of the rightward movement of bearing 7 through the release of the spring force of the disc spring. This prevents errors between the rightward movement of the ejector pin 9 and the thermal expansion elongation of the lead screw 1 due to the gaps in bearing 7, ensuring that bearing 7 as a whole produces the same displacement. This ensures that the thermal expansion elongation of the lead screw 1 is accurately measured by the displacement sensor 10, resulting in small errors, improved compensation effect, and improved accuracy of the machine tool during actual operation. The guide slope 24 guides the dust and impurities entering the movable groove 31, causing them to enter the flange groove 23, which forms a preliminary dust settling area. The limiting protrusion 32, the moving guide groove 33, and the guide block 22 form a labyrinth in the movable groove 31. The labyrinth further blocks the movement of dust, preventing dust from entering the disc spring 4 and bearing 7 through the gaps between the movable groove 31, the pressure cover 3, and the first tail end spacer 2, causing contamination and affecting service life.

[0023] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0024] Although this document frequently uses terms such as lead screw 1; positioning step 11; first tail end spacer 2; spacer flange 21; guide block 22; flange groove 23; guide slope 24; pressure cap 3; movable groove 31; limiting protrusion 32; moving guide groove 33; disc spring 4; second tail end spacer 5; locking nut 6; bearing 7; inner ring 71; outer ring 72; ball 73; fixed seat 8; ejector pin 9; displacement sensor 10, etc., the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

[0025] Contents not described in detail herein are existing technologies known to those skilled in the art. The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A compensation device for thermal error of a machine tool feed axis lead screw, comprising a first tail end spacer (2) and a plurality of bearings (7) sequentially sleeved on the tail end of the lead screw (1), wherein the tail end of the lead screw (1) is provided with a positioning step (11), the inner ring (71) of the bearing (7) is in close contact with the first tail end spacer (2), and the first tail end spacer (2) is in close contact with the positioning step (11), characterized in that It also includes a pressure cap (3), a disc spring (4), a fixed base (8), a ejector pin (9), and a displacement sensor (10). The pressure cap (3) and the disc spring (4) are both sleeved on the first tail end spacer (2). The fixed base (8) is fixed on the frame. The pressure cap (3) is fixed on the fixed base (8). The two ends of the disc spring (4) respectively abut against the pressure cap (3) and the outer ring (72) of the bearing (7). The displacement sensor (10) is fixed on the fixed base (8). The ejector pin (9) is slidably disposed in the fixed base (8). The two ends of the ejector pin (9) are respectively in close contact with the outer ring (72) of the bearing (7) and the end of the displacement sensor (10). When the lead screw (1) expands and elongates due to heat, the positioning step (11) causes the first tail end spacer (2) to move to the right, and the first tail end spacer (2) causes the inner ring (71) of the bearing (7) to move to the right. At this time, the inner ring (71) of the bearing (7) is misaligned with the outer ring (72), and the outer ring (72) of the bearing (7) has space to move to the right. The release of the spring force of the disc spring (4) causes the outer ring (72) of the bearing (7) to move to the right until the outer ring (71) of the bearing (7) moves to the right. 2) The ball (73) is tightly attached to the inner ring (71) of the bearing (7) so that the bearing (7) is assembled. The rightward displacement of the outer ring (72) of the bearing (7) is equal to the rightward displacement of the inner ring (71) of the bearing (7) and equal to the thermal expansion elongation of the lead screw (1). The outer ring (72) of the bearing (7) drives the ejector pin (9) to move to the right. The rightward displacement of the ejector pin (9) is accurately measured by the displacement sensor (10).

2. The compensation device for thermal error of the machine tool feed axis lead screw according to claim 1, characterized in that... It also includes a second tail end spacer (5) and a locking nut (6) sleeved on the tail of the lead screw (1). The tail of the lead screw (1) is provided with a locking thread. The locking nut (6) is installed on the locking thread. Tightening the locking nut (6) makes the locking nut (6) fit tightly against the second tail end spacer (5). The second tail end spacer (5) fits tightly against the inner ring (71) of the bearing (7). The first tail end spacer (2) sequentially drives the inner ring (71) of the bearing (7), the second tail end spacer (5) and the locking nut (6) to move to the right.

3. The compensation device for thermal error of the machine tool feed axis lead screw according to claim 1, characterized in that... The end of the first tail end spacer (2) is provided with a spacer flange (21), and the pressure cap (3) is provided with a movable groove (31). The spacer flange (21) is located in the movable groove (31). The groove wall of the movable groove (31) is provided with a limiting protrusion (32). There is a first movable space between the side of the spacer flange (21) away from the positioning step (11) and the end face of the limiting protrusion (32). The width of the first movable space is greater than the maximum thermal expansion elongation of the lead screw (1).

4. The compensation device for thermal error of the machine tool feed axis lead screw according to claim 3, characterized in that... Below the limiting protrusion (32), there is also a movable guide groove (33). The first tail end spacer (2) has a protruding guide block (22). The guide block (22) is movably located in the movable guide groove (33). There is a second movable space between the side of the guide block (22) and the groove wall of the movable guide groove (33). The width of the second movable space is greater than the maximum thermal expansion elongation of the lead screw (1). The limiting protrusion (32), the movable guide groove (33) and the guide block (22) make a maze form in the movable groove (31).

5. The compensation device for thermal error of the machine tool feed axis lead screw according to claim 3, characterized in that... The spacer flange (21) has a flange groove (23), and the groove wall of the flange groove (23) near the positioning step (11) is a guide slope (24).

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