Lead screw pre-stretching mechanism for numerical control machine tool

Abstract

The lead screw pre-stretching mechanism for the numerical control machine tool comprises a lead screw, a tail end bearing seat is arranged at the end of the lead screw, the tail end bearing seat comprises a tail end bearing sleeve, a plurality of first bearings, a first gasket, a load cell, a load cell gasket, a disc spring and a first outer distance ring, and the first bearings, the first gaskets, the load cell, the load cell gaskets, the disc spring and the first outer distance ring are located in the tail end bearing sleeve. The disc spring, the load cell gasket and the load cell are sequentially arranged on the first outer distance ring in a sleeved mode, the end of the tail end bearing sleeve is bent to form a contact step, the two ends of the disc spring abut against the contact step and the load cell gasket respectively, the end of the lead screw sequentially penetrates through the first outer distance ring, the first gasket and all the first bearings, and the load cell is tightly attached to the first gasket. The first gasket is tightly attached to the first bearing, and the end of the lead screw is exposed out of the tail end bearing seat and provided with a locking nut. The disc spring can well balance the pre-stretching force of the lead screw and the pre-tightening force of the tail end bearing seat, automatic compensation of thermal elongation of the lead screw can be achieved, and high precision and high stability are provided for a transmission system of a machine tool.

Description

Technical Field

[0001] This utility model belongs to the technical field of CNC machine tool equipment, and relates to a lead screw pretensioning mechanism for CNC machine tools. Background Technology

[0002] Currently, CNC machine tools are the main metal-cutting tools in modern high-precision manufacturing, and the structure of the machine tool affects its accuracy. The transmission accuracy of the lead screw plays a crucial role in the machine tool's accuracy and directly relates to its machining precision. Existing machine tools typically use a fixed-end mounting method for the lead screw. Because both ends of the lead screw are fixed supports, when working, the lead screw elongates due to heat. If the lead screw cannot extend to both ends, a lead screw arching phenomenon will occur, causing errors in the lead screw's lead and affecting the machine tool's positioning accuracy. To address this issue, a machine tool with lead screw pre-tensioning has emerged on the market, such as the lead screw pre-tensioning machine tool described in Chinese Patent No. "201320056718.3". The specific structure of this lead screw pre-tensioning machine tool is as follows: it includes a machine tool body, a lead screw located inside the machine tool body, and is locked and fixed at the main end of the lead screw by a conventional precision bearing, a bearing cover, a bearing washer, and a precision lock nut outside the bearing washer. At the secondary end of the lead screw, it is locked and fixed by an angular contact precision bearing, a bearing cover, and a precision lock nut. In the above structure, it is difficult to balance the axial preload of the bearing and the preload of the lead screw under different working conditions. Due to the working environment and the properties of the lead screw itself, the thermal elongation of the lead screw will be greater than the preload. This will directly lead to preload failure, tail bearing preload failure, reduced rigidity of the transmission system, or stress contact between the lead screw shoulder and the inner ring of the tail bearing, resulting in lead screw bending, bearing overheating and burning, and steel balls falling off the track. These problems will seriously affect the accuracy, stability and transmission rigidity of the machine tool. Utility Model Content

[0003] The purpose of this invention is to address the aforementioned problems in the prior art by providing a lead screw pretensioning mechanism for CNC machine tools that can balance the pretension force of the lead screw and the preload of the tail bearing seat.

[0004] The objective of this utility model can be achieved through the following technical solution: A lead screw pretensioning mechanism for CNC machine tools includes a lead screw, the end of which is provided with a tail bearing seat. The tail bearing seat includes a tail bearing sleeve and a plurality of first bearings, first washers, load cells, load cell washers, disc springs, and a first outer spacer located within the tail bearing sleeve. The disc springs, the load cell washers, and the load cells are sequentially sleeved on the first outer spacer. The end of the tail bearing sleeve is bent to form a contact step. The two ends of the disc springs respectively abut against the contact step and the load cell washers. The end of the lead screw is sequentially inserted into the first outer spacer, the first washers, and all the first bearings. The load cells are in close contact with the first washers, and the first washers are in close contact with the first bearings. The end of the lead screw protrudes from the tail bearing seat and is fitted with a locking nut. The locking nut is tightened, causing the first bearings, the first washers, the load cells, and the load cell washers to be sequentially compressed, and the disc springs to be compressed.

[0005] In the aforementioned lead screw pretensioning mechanism for CNC machine tools, the lead screw includes an intermediate section and end sections located at both ends of the intermediate section. The diameter of the end sections is smaller than the diameter of the intermediate section. A positioning step is formed between the end sections and the intermediate section. The end sections cooperate with the tail bearing seat. The first outer spacer ring contacts the positioning step. The first shim is located between the load cell and the first bearing. The first shim ring creates a limiting gap L between the first bearing and the first outer spacer ring. During the tightening of the locking nut, when the first bearing contacts the end face of the first outer spacer ring, the movement of the locking nut stops.

[0006] In the aforementioned lead screw pretensioning mechanism for CNC machine tools, the tail end bearing housing further includes a first pressure cap installed on the end face of the tail end bearing sleeve and a second outer spacer ring located inside the first pressure cap. The end of the lead screw protrudes from the first bearing and is sequentially provided with the second outer spacer ring and the locking nut. The second outer spacer ring is in close contact with the first bearing, and the locking nut is in close contact with the second outer spacer ring.

[0007] In the aforementioned lead screw pretensioning mechanism for CNC machine tools, a front bearing housing is provided on the end section of the lead screw. The front bearing housing includes a front bearing sleeve, a third outer spacer ring located within the front bearing sleeve, and several second bearings. The front bearing housing also includes a second pressure cap installed on the end face of the front bearing sleeve and a fourth outer spacer ring located within the second pressure cap. There are three second bearings in total. The end section of the lead screw passes sequentially through the fourth outer spacer ring, the three second bearings, and the third outer spacer ring. The fourth outer spacer ring contacts the positioning step. The end of the lead screw protruding from the third outer spacer ring is connected to a motor via a coupling.

[0008] In the aforementioned lead screw pretensioning mechanism for CNC machine tools, the front bearing housing is fixed to the mounting table via a front mounting base, the tail bearing housing is fixed to the mounting table via a tail mounting base, a nut is fitted onto the lead screw, the motor drives the lead screw to rotate, and the nut moves axially as the lead screw rotates. A slide rail is mounted on the mounting table, and a slider is provided on the slide rail, with the slider connected to the nut.

[0009] Compared with existing technologies, the lead screw pretensioning mechanism for CNC machine tools, through the locking nut, keeps the lead screw in a pretensioned state and the tail bearing seat in a preloaded state, ensuring the stability of the lead screw during operation and guaranteeing the accuracy of the machined workpiece. Furthermore, the disc spring effectively balances the pretension force of the lead screw and the preload force of the tail bearing seat, and also enables automatic compensation for thermal expansion of the lead screw, providing high precision and stability for the machine tool's transmission system. Simultaneously, it ensures uniform force distribution on the first bearing, reducing wear and increasing bearing life. By setting a limit gap L, the locking process of the locking nut is limited, as is the compression of the disc spring, preventing excessive compression and deformation that could lead to loss of elasticity, and also preventing the locking nut from excessively compressing the first bearing and causing damage. By setting a load cell, the required pretension force is measured, providing sufficient reference data for the subsequent pretensioning process. Attached Figure Description

[0010] Figure 1 This is a cross-sectional structural diagram of the lead screw pretensioning mechanism used in CNC machine tools.

[0011] Figure 2 yes Figure 1 A magnified structural diagram of point A in the middle.

[0012] Figure 3 yes Figure 1 A magnified structural diagram at point B in the middle.

[0013] In the diagram, 1. Lead screw; 11. End section; 12. Positioning step; 2. Front bearing housing; 21. Front bearing sleeve; 22. Third outer spacer ring; 23. Second bearing; 24. Second pressure cap; 25. Fourth outer spacer ring; 3. Tail bearing housing; 31. Tail bearing sleeve; 32. First bearing; 33. First gasket; 34. Load cell; 35. Load cell gasket; 36. Disc spring; 37. First outer spacer ring; 38. First pressure cap; 39. Second outer spacer ring; 310. Locking nut; 311. Contact step; 4. Motor; 5. Front mounting base; 6. Mounting platform; 7. Tail mounting base; 8. Nut; 9. Slide rail; 10. Slider. Detailed Implementation

[0014] 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.

[0015] like Figure 1-3 As shown, the lead screw pretensioning mechanism for CNC machine tools includes a lead screw 1, with a tail bearing housing 3 at its end. The tail bearing housing 3 includes a tail bearing sleeve 31 and several first bearings 32, first washers 33, load cells 34, load cell washers 35, disc springs 36, and a first outer spacer 37 located within the tail bearing sleeve 31. The disc springs 36, load cell washers 35, and load cells 34 are sequentially fitted onto the first outer spacer 37. The end of the tail bearing sleeve 31 is bent to form a contact step 311, and the two ends of the disc springs 36 respectively abut against the contact step 311 and the load cell washers 35. The end of the lead screw 1 passes sequentially through the first outer spacer 37, the first washers 33, and all the first bearings 32. The load cells 34 are in close contact with the first washers 33, and the first washers 33 are in close contact with the first bearings 32. The end of the lead screw 1 protrudes from the tail bearing housing 3 and is fitted with a locking nut 310. Tightening the locking nut 310 causes the first bearing 32, the first washer 33, the load cell 34, and the load cell washer 35 to be compressed in sequence, thus compressing the disc spring 36. This invention allows the lead screw 1 to always be in a pre-tensioned state, and the tail bearing seat 3 to always be in a pre-tightened state. Furthermore, the disc spring 36 can effectively balance the pre-tension force and the pre-tightening force of the tail bearing seat 3, and the first bearing 32 is subjected to uniform force, is not prone to wear, has a long service life, and can also automatically compensate for the thermal expansion of the lead screw 1, providing high precision and high stability for the machine tool's transmission system.

[0016] In the above technical solution: the tail end bearing seat 3 further includes a first pressure cap 38 installed on the end face of the tail end bearing sleeve 31 and a second outer spacer 39 located inside the first pressure cap 38. The end of the lead screw 1 is exposed above the first bearing 32 and is sequentially provided with the second outer spacer 39 and the locking nut 310. The second outer spacer 39 is in close contact with the first bearing 32, and the locking nut 310 is in close contact with the second outer spacer 39.

[0017] In the above technical solution: the lead screw 1 includes an intermediate section and end sections 11 located at both ends of the intermediate section. The diameter of the end sections 11 is smaller than that of the intermediate section, and a positioning step 12 is formed between the end sections 11 and the intermediate section. The end sections 11 cooperate with the tail bearing seat 3, and the first outer spacer 37 contacts the positioning step 12. The first washer 33 is located between the load cell 34 and the first bearing 32, and the first washer 33 creates a limiting gap L between the first bearing 32 and the first outer spacer 37. During the tightening of the locking nut 310, the first bearing 32, the first washer 33, the load cell 34, and the load cell washer 35 continuously move to the left, continuously compressing the disc spring 36, until the first bearing 32 contacts the end face of the first outer spacer 37. At this time, because the first outer spacer 37 is in contact with the positioning step 12, the first outer spacer 37 cannot move to the left relative to the lead screw 1, so the movement of the locking nut 310, the first bearing 32, the first washer 33, the load cell 34, and the load cell washer 35 stops. By setting a limiting gap L, the locking process of the locking nut 310 is limited, and the compression of the disc spring 36 is also limited, so as to prevent the disc spring 36 from being over-compressed and deformed, thus losing its elasticity, and also to prevent the locking nut 310 from over-pressing the first bearing 32 and causing damage to the first bearing 32.

[0018] In the above technical solution: a front bearing seat 2 is provided on the end section 11 of the lead screw 1. The front bearing seat 2 includes a front bearing sleeve 21, a third outer spacer 22 located inside the front bearing sleeve 21, and several second bearings 23. The front bearing seat 2 also includes a second pressure cap 24 installed on the end face of the front bearing sleeve 21 and a fourth outer spacer 25 located inside the second pressure cap 24. There are three second bearings 23 in total. The end section 11 of the lead screw 1 passes through the fourth outer spacer 25, the three second bearings 23, and the third outer spacer 22 in sequence. The fourth outer spacer 25 contacts the positioning step 12. The end of the lead screw 1 exposed above the third outer spacer 22 is connected to the motor 4 through a coupling.

[0019] In the above technical solution: the front bearing housing 2 is fixed to the mounting platform 6 via the front mounting base 5, and the rear bearing housing 3 is fixed to the mounting platform 6 via the rear mounting base 7. A nut 8 is fitted onto the lead screw 1, and the motor 4 drives the lead screw 1 to rotate, causing the nut 8 to move axially with the rotation of the lead screw 1. A slide rail 9 is mounted on the mounting platform 6, and a slider 10 is mounted on the slide rail 9. The slider 10 is connected to the nut 8, and the slider 10 and the slide rail 9 cooperate to guide the movement of the nut 8.

[0020] In the lead screw pretensioning mechanism of this CNC machine tool, the locking nut 310 keeps the lead screw 1 in a pretensioned state and the tail bearing seat 3 in a preloaded state, ensuring the stability of the lead screw 1 during operation and the accuracy of the machined workpiece. Furthermore, the disc spring 36 effectively balances the pretension force of the lead screw and the preload force of the tail bearing seat 3, and also enables automatic compensation for the thermal expansion of the lead screw 1, providing high precision and high stability for the machine tool's transmission system. Simultaneously, it ensures uniform force distribution on the first bearing 32, reducing wear and increasing bearing life. By setting a limit gap L, the locking process of the locking nut 310 is limited, as is the compression of the disc spring 36, preventing excessive compression and deformation that could lead to loss of elasticity, and also preventing the locking nut 310 from excessively compressing the first bearing 32 and damaging it. By setting a load cell 34, the required pretension force is measured, providing sufficient reference data for the subsequent pretensioning process.

[0021] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

[0022] Although this document frequently uses terms such as lead screw 1; end section 11; positioning step 12; front bearing seat 2; front bearing sleeve 21; third outer spacer 22; second bearing 23; second pressure cap 24; fourth outer spacer 25; tail bearing seat 3; tail bearing sleeve 31; first bearing 32; first gasket 33; load cell 34; load cell gasket 35; disc spring 36; first outer spacer 37; first pressure cap 38; second outer spacer 39; locking nut 310; contact step 311; motor 4; front mounting base 5; mounting platform 6; tail mounting base 7; nut 8; slide rail 9; slider 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 this utility model; interpreting them as any kind of additional limitation would contradict the spirit of this utility model.

[0023] Contents not described in detail herein are existing technologies known to those skilled in the art. The specific embodiments described herein are merely illustrative examples illustrating the spirit of this 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 this invention or exceeding the scope defined by the appended claims.

Claims

1. A lead screw pretensioning mechanism for a CNC machine tool, comprising a lead screw (1), wherein the end of the lead screw (1) is provided with a tail bearing seat (3), characterized in that... The tail bearing housing (3) includes a tail bearing sleeve (31) and a plurality of first bearings (32), first washers (33), load cells (34), load cell washers (35), disc springs (36), and a first outer spacer (37) located within the tail bearing sleeve (31). The disc springs (36), the load cell washers (35), and the load cells (34) are sequentially sleeved on the first outer spacer (37). The end of the tail bearing sleeve (31) is bent to form a contact step (311). The two ends of the disc springs (36) respectively abut against the contact step (311) and the load cell washers (35). The end of the lead screw (1) is sequentially inserted into the first outer spacer (37), the first washer (33), and all of the first bearings (32). The load cell (34) is in close contact with the first washer (33), and the first washer (33) is in close contact with the first bearing (32). The end of the lead screw (1) is exposed in the tail bearing seat (3) and a locking nut (310) is installed. The locking nut (310) is pressed and the first bearing (32), the first washer (33), the load cell (34), and the load cell washer (35) are squeezed in sequence, and the disc spring (36) is compressed.

2. The lead screw pre-tensioning mechanism for CNC machine tools according to claim 1, characterized in that... The lead screw (1) includes an intermediate section and end sections (11) located at both ends of the intermediate section. The diameter of the end sections (11) is smaller than that of the intermediate section. A positioning step (12) is formed between the end sections (11) and the intermediate section. The end sections (11) cooperate with the tail bearing seat (3). The first outer spacer (37) contacts the positioning step (12). The first gasket (33) is located between the load cell (34) and the first bearing (32). The first gasket (33) creates a limiting gap L between the first bearing (32) and the first outer spacer (37). During the process of tightening the locking nut (310), when the first bearing (32) contacts the end face of the first outer spacer (37), the movement of the locking nut (310) stops.

3. A lead screw pre-tensioning mechanism for CNC machine tools according to claim 1, characterized in that... The tail end bearing housing (3) also includes a first pressure cap (38) installed on the end face of the tail end bearing sleeve (31) and a second outer spacer (39) located inside the first pressure cap (38). The end of the lead screw (1) is exposed above the first bearing (32) and the second outer spacer (39) and the locking nut (310) are sequentially inserted therethrough. The second outer spacer (39) is in close contact with the first bearing (32), and the locking nut (310) is in close contact with the second outer spacer (39).

4. A lead screw pre-tensioning mechanism for CNC machine tools according to claim 2, characterized in that... The end section (11) of the lead screw (1) is provided with a front bearing seat (2). The front bearing seat (2) includes a front bearing sleeve (21), a third outer spacer (22) located in the front bearing sleeve (21), and several second bearings (23). The front bearing seat (2) also includes a second pressure cap (24) installed on the end face of the front bearing sleeve (21) and a fourth outer spacer (25) located in the second pressure cap (24). There are three second bearings (23). The end section (11) of the lead screw (1) passes through the fourth outer spacer (25), the three second bearings (23), and the third outer spacer (22) in sequence. The fourth outer spacer (25) is in contact with the positioning step (12). The end of the lead screw (1) exposed in the third outer spacer (22) is connected to the motor (4) through a coupling.

5. A lead screw pre-tensioning mechanism for CNC machine tools according to claim 4, characterized in that... The front bearing seat (2) is fixed on the mounting platform (6) by the front mounting seat (5), and the tail bearing seat (3) is fixed on the mounting platform (6) by the tail mounting seat (7). A nut (8) is fitted on the lead screw (1). The motor (4) drives the lead screw (1) to rotate. The nut (8) moves axially as the lead screw (1) rotates. A slide rail (9) is installed on the mounting platform (6). A slider (10) is provided on the slide rail (9). The slider (10) is connected to the nut (8).

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