Ball screw and injection molding machine

Abstract

The present invention discloses a ball screw, which comprises a screw shaft, a nut, a plurality of balls and a circulation path. The outer peripheral surface of the screw shaft has a first raceway groove spirally arranged in the axial direction of the screw shaft. The inner peripheral surface of the nut has a second raceway groove arranged in alignment with the first raceway groove. The nut is sleeved on the screw shaft. The plurality of balls are received between the first raceway groove and the second raceway groove. The first raceway groove spirally forms a first convex portion on the screw shaft. There is a height difference between the two side edges of the first convex portion. The purpose is to be able to make full use of the load-bearing function of the screw shaft. By adjusting the shape of the edge of the raceway groove, the load-bearing capacity of the screw shaft in a single direction can be improved, and the risk of plastic deformation of the ball race edge of the screw shaft or its corresponding ball screw can be reduced. In addition, an injection molding machine is also provided, which has the functional effect of applying the above screw, so that its single-direction load capacity is prominent.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission devices, and particularly relates to a ball screw and an injection molding machine. Background Art

[0002] A ball screw includes a screw shaft, a nut, and a plurality of balls clamped between the screw shaft and the nut. A spiral ball rolling groove for the balls to perform rolling motion is formed on the outer peripheral surface of the screw shaft. Through the rolling of the balls, relatively easy movement can be obtained.

[0003] Currently, basically all ball screws on the market can bear loads in both positive and negative axial directions in the axial direction of the screw shaft. That is, when the ball screw rotates forward, it can bear positive axial load, and when it rotates backward, it can bear reverse axial load, and the load-bearing capacities in both directions are basically equal. However, in some special application fields, when the ball screw is working, the main axial load only comes from one direction, and when working in the reverse direction, there is basically no axial load or the axial load is very small. For example, in the injection molding machine industry, the injection screw bears a very large axial load when performing the injection action, while when performing the reverse retraction action, its axial load is very small and can be basically ignored. The design and selection of the screw mainly consider the axial load during forward injection, and the selection result is often that the forward load-bearing capacity of the screw is insufficient, while a large functional waste is formed in the reverse direction. In view of this phenomenon, if the structure design of the screw can be optimized to transfer the unused reverse load-bearing function to the forward load-bearing function that needs to be strengthened, good effects will be achieved in terms of cost and function. Summary of the Invention

[0004] The purpose of the present invention is to provide a ball screw that can make full use of the load-bearing function of the screw shaft. By adjusting the shape of the edge of the raceway groove, the load-bearing capacity of the screw shaft in a single direction can be improved, and the risk of plastic deformation at the edge of the ball race of the screw shaft or its corresponding ball screw can be reduced.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] A ball screw, comprising a screw shaft, the outer peripheral surface of the screw shaft having a first raceway groove spirally arranged in the axial direction of the screw shaft; a nut, the inner peripheral surface of the nut having a second raceway groove arranged opposite to the first raceway groove, the nut being sleeved on the screw shaft and capable of rotating and shifting along the axial direction of the screw shaft; a plurality of balls, the plurality of balls being received between the first raceway groove and the second raceway groove and capable of moving in a rolling manner; and a circulation path formed by the alignment of the first raceway groove and the second raceway groove and enabling the plurality of balls to circulate within the limit range of the circulation path; wherein the first raceway groove spirally forms a first convex portion on the screw shaft, and there is a height difference between the two side edges of the first convex portion.

[0007] Compared with the prior art, in a ball screw of the present invention, the first raceway groove spirally and intermittently forms a first convex portion integral with the screw shaft, and there is a height difference between the two side edges of the first convex portion. Therefore, it will cause the area and the edge height of the inner peripheral surface of the first ball running groove to change, so that no matter whether the ball screw is working in the forward direction or the reverse direction of the nut, the contact position between the ball and the inner peripheral surface of the first ball running groove changes. Relatively, the contact position between the ball and the inner peripheral surface of the second raceway groove also changes, which is equivalent to changing the force-bearing position of the ball, and combined with the diameter of the screw shaft itself, the bearing capacity of the ball is changed, thereby improving the single-direction load capacity of the ball screw.

[0008] Further, the second raceway groove intermittently forms a second convex portion on the inner wall of the nut along the axial direction of the nut, and there is a height difference between the two side edges of the second convex portion.

[0009] Further, the first convex portion has an inclined portion continuously extending from the higher side of the first convex portion to the lower side of the first convex portion, and the inclined portion is one of a flat inclined portion, an arc-shaped inclined portion or a stepped inclined portion.

[0010] Further, the ball screw has a forward load use state and a reverse load use state;

[0011] When the ball screw is in the forward load use state, the included angle between the line connecting the contact point of the ball and the first raceway groove and the center of the current position of the ball and the perpendicular line in the axial direction of the screw shaft intersects to form a first included angle, and the value of the first included angle is limited within the range of being greater than or equal to 50 degrees and less than or equal to 75 degrees;

[0012] When the ball screw is in the reverse load use state, the included angle between the line connecting the contact point of the ball and the first raceway groove and the center of the current position of the ball and the perpendicular line in the axial direction of the screw shaft intersects to form a second included angle, and the magnitude of the second included angle is smaller than the magnitude of the first included angle.

[0013] Another aspect of the present invention relates to a ball screw, including a screw shaft, the outer peripheral surface of the screw shaft having a first raceway groove spirally provided in the axial direction of the screw shaft; a nut, the inner peripheral surface of the nut having a second raceway groove disposed opposite to the first raceway groove, the nut being sleeved on the screw shaft and capable of rotating and shifting in the axial direction of the screw shaft; a plurality of balls, the plurality of balls being received between the first raceway groove and the second raceway groove and capable of moving in a rolling manner; and a circulation path formed by the alignment of the first raceway groove and the second raceway groove and enabling the plurality of balls to circulate within the limit range of the circulation path; wherein, there is a height difference between the two side edges of the first raceway groove.

[0014] Compared with the prior art, in a ball screw according to another aspect of the present invention, there is a height difference between the two side edges of the first raceway groove, so that the adjustment range of the balls in the first raceway groove in the horizontal direction is changed, thereby causing the contact position of the balls with the inner peripheral surface of the second raceway groove to change relatively whether the ball screw is working in the forward or reverse direction of the nut. Equivalently, the force-bearing position of the balls is changed, and combined with the diameter of the screw shaft itself, the bearing capacity of the balls is changed, thereby improving the single-direction load capacity of the ball screw.

[0015] Further, the outer wall of the screw shaft and the inner wall of the nut have a similar shape, and there is a height difference between the two side edges of the second raceway groove.

[0016] Further, the first raceway groove spirally forms a first convex portion on the screw shaft along the axial direction of the screw shaft, and the second raceway groove is spaced apart and forms a second convex portion on the inner wall of the nut along the axial direction of the nut; the end surfaces of the first convex portion and the second convex portion are both flat inclined surfaces with a single slope or non-uniform inclined surfaces with a changing slope.

[0017] Further, the first convex portion has an inclined portion continuously extending from the higher side of the first convex portion to the lower side of the first convex portion, and the inclined portion is one of a flat inclined portion, an arc-shaped inclined portion or a stepped inclined portion.

[0018] Further, the ball screw has a forward-load use state and a reverse-load use state;

[0019] When the ball screw is in the forward-load use state, the intersection of the line connecting the contact point of the ball with the first raceway groove and the center of the current position of the ball and the perpendicular line in the axial direction of the screw shaft has a first included angle, and the value of the first included angle is limited within a range greater than or equal to 50 degrees and less than or equal to 75 degrees;

[0020] When the ball screw is in the reverse load use state, the line connecting the contact point of the ball and the first raceway groove to the center of the current position of the ball intersects with the perpendicular line in the axial direction of the screw shaft to form a second included angle, and the magnitude of the second included angle is smaller than the magnitude of the first included angle.

[0021] The present invention also provides an injection molding machine, including the ball screw as described above.

[0022] For better understanding and implementation, the present invention will be described in detail below with reference to the accompanying drawings. Description of the Drawings

[0023] Figure 1 is a partial structural schematic diagram of the ball screw of the present invention;

[0024] Figure 2 is a schematic diagram showing the bottom width of the cross-section of the first raceway groove on the screw shaft in the screw shaft;

[0025] Figure 3 is a schematic diagram showing the first raceway groove on the screw shaft in a state of having a reaction force indication with the ball in the screw shaft;

[0026] Figure 4 is a schematic diagram of the force-bearing area in the circulation path of the ball screw of the present invention;

[0027] Figure 5 is a partial structural schematic diagram of the ball screw when the nut load direction is to the right;

[0028] Figure 6 is a partial structural schematic diagram of the ball screw when the nut load direction is to the left;

[0029] Figure 7 is a structural schematic diagram of a preferred solution of the ball screw shown in Embodiment III of the present invention. Detailed Embodiments

[0030] To better elaborate the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope protected by the embodiments of the present application.

[0032] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0033] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects and do not have to be used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0034] In addition, in the description of the present application, unless otherwise specified, "a plurality of" means two or more. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0035] As Figure 1 shown, a ball screw includes a screw shaft 100, the outer peripheral surface of the screw shaft 100 has a first raceway groove 101 spirally arranged around the axis of the screw shaft 100; a nut 200, the inner peripheral surface of the nut 200 has a second raceway groove 201 arranged in alignment with the first raceway groove 101, the nut 200 is sleeved on the screw shaft 100 and can rotate and shift along the axis direction of the screw shaft 100; a plurality of balls 300, the plurality of balls 300 are received between the first raceway groove 101 and the second raceway groove 201 and can move in a rolling manner; and a circulation path formed by the alignment of the first raceway groove 101 and the second raceway groove 201, and enabling the plurality of balls 300 to circulate within the limit range of the circulation path; wherein, the first raceway groove 101 spirally forms a first convex portion 102 on the screw shaft 100, and there is a height difference H1 between the two side edges of the first convex portion 102.

[0036] Compared with the prior art, for a ball screw of the present invention, the first raceway groove 101 spirally and intermittently forms a first convex portion 102 integral with the lead screw shaft 100. There is a height difference H1 between the two side edges of the first convex portion 102. As a result, the area and the edge height of the inner circumferential surface of the rolling groove of the first ball 300 are changed. Thus, no matter whether the ball screw is working in the positive direction or the reverse direction of the nut 200, the contact position between the ball 300 and the inner circumferential surface of the rolling groove of the first ball 300 is changed. Relatively, the contact position between the ball 300 and the inner circumferential surface of the second raceway groove 201 is also changed, which is equivalent to changing the force-bearing position of the ball 300. And combined with the diameter of the lead screw shaft 100 itself, the bearing capacity of the ball 300 is changed, thereby improving the single-direction load capacity of the ball screw.

[0037] In this embodiment, a first raceway groove 101 with a constant lead and spirally formed is formed on the outer circumferential surface of the lead screw shaft 100, and a second raceway groove 201 with a constant lead and spirally formed is formed on the inner circumferential surface of the nut 200. After the first raceway groove 101 and the second raceway groove 201 are opposed to each other, a circulation path is formed. The cross-section of the circulation path is in an approximately elliptical shape, and the major axis of the cross-section of the circulation path is larger than the diameter of the ball 300.

[0038] As Figure 2 shown, a perpendicular line from the midpoint of the arc-shaped cross-section of the first raceway groove 101 intersects the edge of the arc-shaped cross-section at a first intersection point 103. The straight-line paths between the first intersection point 103 and the two side edges of the first raceway groove 101 are N1 and N2 respectively. The straight-line distance N2 from the first intersection point 103 to the higher side edge of the first raceway groove 101 is greater than the straight-line distance N1 from the first intersection point 103 to the lower side edge of the first raceway groove 101.

[0039] This increases the vector range of the force-bearing direction of the rolling element at this position. The increased range is the spacing of the height difference H1 between the two side edges of the first convex portion 102. And within this spacing, the closer the ball 300 is to one end of the first raceway groove 101, the closer the direction of the mutual force between the ball 300 and the lead screw shaft 100 is to the axial direction of the lead screw shaft 100. As a result, when the lead screw shaft 100 is under force, the force perpendicular to the lead screw shaft 100 can be reduced, so that the extrusion on the lead screw shaft 100 is reduced, and thus the risk of the lead screw shaft 100 being plastically deformed can be reduced.

[0040] In addition, it should be noted that as described above, there is a first distance between the perpendicular heights of the two side edges of the first convex portion 102 with respect to the lead screw shaft 100. This limits that the end face of the first convex portion 102 can be equivalently regarded as a continuous and descending inclined plane.

[0041] Of course, the above can be described as having an inclined portion 103 on the first convex portion 102 that continuously extends from the higher side of the first convex portion 102 to the lower side of the first convex portion 102. The inclined portion 103 is one of a flat inclined portion 103, an arc-shaped inclined portion 103, or a folded inclined portion 103. That is, as long as the two side edges of the first convex portion 102 are in a state with a height difference, the functional effects of the first convex portion 102 can be achieved.

[0042] The second raceway groove 201 is formed at intervals along the axial direction of the nut 200 on the inner wall of the nut 200 to form a second convex portion 202, and there is a height difference H1 between the two side edges of the second convex portion 202.

[0043] As Figure 1 shown, in order to keep the ball screw stable during application, the shapes of the first convex portion 102 and the second convex portion 202 are quite similar, and there is a clearance area 104 between the first convex portion 102 and the second convex portion 202. The purpose of this clearance area 104 is to prevent excessive abutment between the first convex portion 102 and the second convex portion 202, which may affect the ascending or descending ability of the nut 200.

[0044] Furthermore, when the second convex portion 202 spirally ascends or descends along the axial direction of the screw shaft 100 with the nut 200, the clearance area 104 is always maintained between the first convex portion 102 and the second convex portion 202, so that the ball 300 located in the circulation path can move along the axial direction of the screw shaft 100 in the circulation path, thus meeting the application on the ball screw described in the present invention.

[0045] In summary, as Figures 1 to 3 shown, it is described according to the force applied to the screw shaft 100. In this embodiment, the screw shaft 100 is a rigid body and will not have obvious elastic deformation after abutting against the rolling elements.

[0046] When the rolling element abuts against a point in the first raceway groove 101, there is an interaction force with a point in the first raceway groove 101. The reaction force from the screw shaft 100 is Fm, which can be decomposed into a force Fm1 perpendicular to the axial direction of the screw shaft 100 and a force Fm2 parallel to the axial direction of the screw shaft 100. Among them, Fm1 affects the magnitude of the force that deforms the screw shaft 100 plastically, and Fm2 affects the load magnitude of the screw shaft 100. Since the first raceway groove 101 is an arc-shaped groove, as the contact point position of the force in the raceway groove 1 changes, the corresponding Fm1 and Fm2 also change.

[0047] As the load magnitude gradually changes, the stress point within the raceway groove 1 gets closer and closer to the first section 23a. Generally speaking, the magnitude of the ultimate force at which the lead screw shaft 100 is plastically deformed is constant. In this embodiment, the lead screw shaft 100 increases the limit range of the direction adjustment of the vector force provided by the load. In the case of the load being in the limit state, the magnitude of Fm2 is equivalently increased, and Fm1 can still be maintained within the plastically deformed range. In this way, without affecting the normal use state of the lead screw shaft 100, the unidirectional load capacity of the lead screw shaft 100 can be improved.

[0048] In addition, as Figure 4 shown, the arc-shaped cross-section of the raceway groove 1 has a lowest point S. Taking this lowest point S as the boundary, the area M1 of the first raceway groove 101 closer to the higher side of the first convex portion 102 is greater than the area M2 of the first raceway groove 101 closer to the lower side of the first convex portion 102; correspondingly, the area M3 of the second raceway groove 201 closer to the lower side of the second convex portion 202 is smaller than the area M4 of the second raceway groove 201 closer to the higher side of the second convex portion 202.

[0049] According to the above, the position range within which the ball 300 of the present embodiment can shift on the raceway groove 1 of the lead screw shaft 100 changes. The position adjustment range of the ball 300 closer to the higher side of the first raceway groove 101 within the raceway groove is large, and the position adjustment range closer to the second raceway groove 201 within the first raceway groove 101 is small.

[0050] Embodiment 2

[0051] Another aspect of the present invention relates to a ball screw, including a lead screw shaft 100, the outer peripheral surface of the lead screw shaft 100 having a first raceway groove 101 spirally arranged in the axial direction of the lead screw shaft 100; a nut 200, the inner peripheral surface of the nut 200 having a second raceway groove 201 arranged in alignment with the first raceway groove 101, the nut 200 being sleeved on the lead screw shaft 100 and capable of rotating and shifting along the axial direction of the lead screw shaft 100; a plurality of balls 300, the plurality of balls 300 being received between the first raceway groove 101 and the second raceway groove 201 and capable of moving in a rolling manner; and a circulation path formed by the alignment of the first raceway groove 101 and the second raceway groove 201, enabling the plurality of balls 300 to circulate within the limit range of the circulation path; wherein, there is a height difference H1 between the two side edges of the first raceway groove 101.

[0052] Compared with the prior art, a ball screw in another way in this embodiment has a height difference H1 between the two side edges of the first raceway groove 101. As a result, the adjustment range of the ball 300 in the first raceway groove 101 in the horizontal direction is changed. Taking the axial perpendicular direction of the first raceway groove 101 as the boundary, the adjustment ranges of the balls 300 are distributed unevenly in size. Thus, no matter whether the ball screw works in the positive or negative direction of the nut 200, the contact position between the ball 300 and the inner peripheral surface of the second raceway groove 201 also changes, which is equivalent to changing the extreme value of the force on the ball 300. And combined with the diameter of the lead screw shaft 100 itself, the bearing capacity in the axial direction of the lead screw shaft 100 is equivalently changed, thereby improving the single-direction load capacity of the ball screw.

[0053] As Figures 5 to 6 shown, Figure 5 The figure shows the local structural state of the ball screw when the load direction of the nut 200 is to the right. When the load direction of the nut 200 is to the right, the contact point position between the ball 300 and the raceway groove of the lead screw shaft 100 is close to the right edge of the raceway groove of the lead screw shaft 100 in the figure, and the contact point position between the ball 300 and the second raceway groove 201 is close to the left edge of the load raceway groove in the figure. The distance between this contact point and the bottom of the raceway groove 1 is denoted as the first height.

[0054] Figure 6 The figure shows the local structural state of the ball screw when the load direction of the nut 200 is to the left. As Figure 6 shown, when the load direction of the nut 200 is to the left, the contact point position between the ball 300 and the first raceway groove 101 of the lead screw shaft 100 is close to the left edge of the raceway groove of the lead screw shaft 100 in the figure, and the contact point position between the ball 300 and the second raceway groove 201 is close to the right edge of the load spiral groove in the figure. The distance between this contact point and the bottom of the first rolling groove is denoted as the second height.

[0055] According to Figure 5 and Figure 6 the above content, it can be determined that Figure 6 what is expressed is the local action state of the ball screw when the load of the nut 200 is relatively small. Although the first height is close to the edge of the raceway groove of the lead screw shaft 100, due to the relatively small reverse load, there is no risk of failure. Figure 6 what is expressed is the local action state of the ball screw when the load of the nut 200 is relatively large. There is still a relatively long distance between the second height and the edge of the raceway groove 1 of the lead screw shaft 100, indicating that the ball screw still has a relatively high stress.

[0056] Next, according to Figure 5 andFigure 6 Describe the force acting on the ball 300.

[0057] First, in this embodiment, the nut 200 and the lead screw shaft 100 are rigid bodies and will not have obvious elastic deformation after contacting the ball 3005.

[0058] When the load direction of the nut 200 is to the right, the nut 200 and the lead screw shaft 100 are in contact and stressed due to the reaction forces Fn1 - Fn3 and Fs1 - Fs3 from the ball 3005 in the following manner. The reaction forces Fn1 - Fn3 and Fs1 - Fs3 respectively maintain equal magnitudes and opposite directions.

[0059] When the load direction of the nut 200 is to the left, the nut 200 and the lead screw shaft 100 are in contact and stressed due to the reaction forces Fn1' - Fn3' and Fs1' - Fs3' from the ball 300 in the following manner. The reaction forces Fn1' - Fn3' and Fs1' - Fs3' respectively maintain equal magnitudes and opposite directions.

[0060] Furthermore, considering the operating state of the ball screw of the present invention, the ball screw has a forward - load operating state and a reverse - load operating state. When the ball screw is in the forward - load operating state, the line connecting the contact point of the ball 300 and the first raceway groove 102 and the center of the current position of the ball 300 intersects with the perpendicular line in the axial direction of the lead screw shaft 100 at a first angle α. The value of the first angle α is restricted within the range greater than or equal to 50 degrees and less than or equal to 75 degrees.

[0061] When the ball screw is in the reverse - load operating state, the line connecting the contact point of the ball and the first raceway groove 102 and the center of the current position of the ball 300 intersects with the perpendicular line in the axial direction of the lead screw shaft 100 at a second angle β. The magnitude of the second angle β is smaller than the magnitude of the first angle α.

[0062] In contrast, as can be seen from the above, for the same ball 300 in the first raceway groove 102 under the forward load use state and the reverse load use state, in the forward load use state, when the ball moves to rest, the value of the above-mentioned first included angle α presented is between 50° and 75°. Considering the structural elasticity of the ball screw and the gap between the screw shaft 100 and the nut, the value of the above-mentioned first included angle α is an uncertain value and varies within the range of 50° to 75°. However, it can be determined that due to the height difference between the two side edges of the first raceway groove 102, the cross-section of the first raceway groove 102 is not symmetrical about the vertical direction, so that the size of the second included angle β is bound to be smaller than the size of the first included angle α. Correspondingly, the load-bearing capacity of the ball 300 in the reverse load use state is less than that in the forward load use state.

[0063] Embodiment 3

[0064] Specifically, as a preferred solution of the present invention, as Figure 7 shown, Figure 7 The figure shows a partial structure of the screw shaft 100 of this embodiment. A screw shaft 100 is formed with a raceway groove 1 having an arc-shaped cross-section and arranged spirally. The rolling elements can roll on the raceway groove 1. A first convex portion 102 is formed at the edge of the raceway groove 1 between the raceway grooves 1; a first deformation line 21a is provided on the first convex portion 102, and the interval between the edge of the raceway groove 1 and the first deformation line 21a is the first section 23a; a second deformation line 21b is provided on the first convex portion 102, and the first convex portion 102 extends downward and narrows from the first deformation line 21a to the second deformation line 21b to form an inclined second section 23b between the first deformation line 21a and the second deformation line 21b; the interval between the second deformation line 21b and the other edge of the raceway groove 1 is the third section 23c; the first deformation line 21a and the second deformation line 21b are arranged in a staggered manner, so that there is a height difference H1 relative to the flat surface between the height of the termination position of the first section 23a and the height of the starting position of the third section 23c.

[0065] This embodiment describes a lead screw shaft 100, whose main effect is that it forms a raceway groove 1 with an arc-shaped cross-section and is spirally arranged, and rolling elements can roll on the raceway groove 1. It includes a first convex portion 102 formed between the raceway grooves 1 and located at the edge of the raceway groove 1. On the first convex portion 102, there are a first deformation line 21a and a second deformation line 21b, and a first section 23a, a second section 23b, and a third section 23c formed by the first deformation line 21a and the second deformation line 21b. Thus, there is a height difference H1 relative to the flat surface between the height of the termination position of the first section 23a and the height of the starting position of the third section 23c, so that the force vector range of the lead screw shaft 100 in one direction increases, which is equivalent to expanding the range of the force application points of the lead screw shaft 100 in this direction. Therefore, the load utilization rate of the lead screw shaft 100 in a single direction can be improved, and further, the risk of plastic deformation of the spiral groove edge of the lead screw shaft 100 can be reduced.

[0066] As Figure 2 and Figure 7 shown, the first section 23a and the third section 23c are flatly arranged, and the first section 23a and the third section 23c are relatively parallel; the second section 23b is an inclined plane arranged with a single slope.

[0067] The purpose of such a setting is also to simplify the structure of the lead screw shaft 100. When constructing the lead screw shaft 100, only by opening the raceway groove 1, the second section 23b, and the third section 23c can the lead screw shaft 100 described in the present invention be formed, which can simplify the production of the lead screw shaft 100.

[0068] From another perspective, there will surely be users who will set the first section 23a obliquely, and the corresponding third section 23c is also obliquely arranged. Although this setting method can ensure that when the lead screw shaft 100 is in use, the balls 300 can all abut against the lead screw shaft 100 to the maximum extent, but this will cause the equivalent thickness of the lead screw shaft 100 at this position to decrease, and at this time, the lead screw shaft 100 is extremely easy to be plastically deformed under load.

[0069] In order to make the overall shape of the lead screw shaft 100 regular, the first deformation line 21a and the second deformation line 21b are both arranged parallel to the two side edges of the raceway groove 1, so that the first section 23a, the second section 23b, and the third section 23c are arranged with equal widths on the first convex portion 102, and the mapped shape of the second section 23b on the flat surface is parallel to the mapped shape of the flat surface.

[0070] In addition, the widths of the first section 23a and the third section 23c can be equal or not equal. Taking the case where the widths of the first section 23a and the third section 23c are not equal as an example, as Figures 1 to 2As shown, the widths of the first section 23a and the third section 23c are not equal, and the width of the first section 23a is larger. Since the load direction is different when the lead screw shaft 100 is in use, the magnitude of the force received is also different. The thickness of the first section 23a corresponding to the lead screw shaft 100 is also larger, making the corresponding plastic forming more difficult, with a stronger load capacity. Its disadvantage is that when the lead screw shaft 100 returns without bearing a load, the rolling elements may abut against the second section 23b, making it difficult to apply the lead screw shaft 100 and losing its effectiveness.

[0071] Therefore, it is preferable to arrange the first section 23a, the second section 23b, and the third section 23c with equal widths on the first convex portion 102, and the widths of the first section 23a, the second section 23b, and the third section 23c can be visually distinguished, that is, the first section 23a, the second section 23b, and the third section 23c have a significantly recognizable width range.

[0072] An explanation is given based on the force received on the lead screw shaft 100. In this embodiment, the lead screw shaft 100 is a rigid body and will not have obvious elastic deformation after abutting against the rolling elements.

[0073] A second raceway groove 201 opposite to the raceway groove 1 of the lead screw shaft 100 is formed on the inner peripheral surface of the nut 200. The raceway groove 1 and the second raceway groove 201 face each other and constitute a rolling passage 4; a plurality of balls 300 are provided in the ball screw, and the plurality of balls 300 can move in the rolling passage 4 in a rolling motion mode.

[0074] In addition, as Figure 7 shown, a second convex portion 202202 is formed on the inner peripheral surface of the nut 200 between the second raceway grooves 201. The second convex portion 202202 has a fourth section 35a, a fifth section 35b, and a sixth section 35c that are respectively opposite to the shapes and sizes of the first section 23a, the second section 23b, and the third section 23c; wherein, there is an area difference between the first section 23a and the fourth section 35a, an area difference between the third section 23c and the sixth section 35c, and the areas of the second section 23b and the fifth section 35b are equivalent.

[0075] According to the above, correspondingly, the second convex portion 202202 on the nut 200 has a third deformation line 34a and a fourth deformation line 34b. The interval between the edge of the second raceway groove 201 and the third deformation line 34a is the fourth section 35a. The second convex portion 202202 extends downward and narrows from the third deformation line 34a to the fourth deformation line 34b to form an inclined fifth section 35b located between the third deformation line 34a and the fourth deformation line 34b; the interval between the third deformation line 34a and the other edge of the raceway groove 1 is the sixth section 35c.

[0076] Of course, there is an area difference between the first section 23a and the fourth section 35a, and there is an area difference between the third section 23c and the sixth section 35c. The purpose is that when the ball screw bears a unidirectional load, in order to enable the balls 300 in the rolling path 4 to contact the first raceway groove 101 and the second raceway groove 201, the force is located at the points or the area range on the first raceway groove 1 and the second raceway groove 201. Then, after the first raceway groove 1 and the second raceway groove 201 are aligned, there must be a clearance space 51 between the third section 23c and the fourth section 35a and their corresponding balls 300, which can place the balls 300 to abut against the other side of the contact point relative to the nut 200, so as to avoid causing the failure of the ball screw.

[0077] The ball screws of the above embodiments are also applicable to applications such as stamping machines, bending machines, injection molding machines, and compression molding machines where a large axial load acts on the ball screw. This is because the deviation of the load distribution of the balls 300 is reduced, thereby achieving the long life of the ball screw. However, the use of the ball screw of the present invention is not particularly limited.

[0078] According to the disclosure and teachings of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A ball screw, characterized in that, it includes a lead screw shaft, the outer peripheral surface of the lead screw shaft having a first raceway groove spirally provided in the axial direction of the lead screw shaft; a nut, the inner peripheral surface of the nut having a second raceway groove provided in alignment with the first raceway groove, the nut being sleeved on the lead screw shaft and capable of rotating and shifting in the axial direction of the lead screw shaft; a plurality of balls, the plurality of balls being received between the first raceway groove and the second raceway groove and capable of moving in a rolling manner; and a circulation path, formed by the alignment of the first raceway groove and the second raceway groove and enabling the plurality of balls to circulate within the limits of the circulation path; wherein, the first raceway groove spirally forms a first convex portion on the lead screw shaft, and there is a height difference between the two side edges of the first convex portion.

2. The ball screw according to claim 1, characterized in that, the second raceway groove forms second convex portions on the inner wall of the nut at intervals along the axial direction of the nut, and there is a height difference between the two side edges of the second convex portions.

3. The ball screw according to claim 1, characterized in that, the first convex portion has an inclined portion continuously extending from the higher side of the first convex portion to the lower side of the first convex portion, and the inclined portion is one of a flat inclined portion, an arc-shaped inclined portion, or a stepped inclined portion.

4. The ball screw according to any one of claims 1 to 3, characterized in that, the ball screw has a forward load use state and a reverse load use state; when the ball screw is in the forward load use state, the angle formed by the intersection of the line connecting the contact point of the ball with the first raceway groove and the center of the current position of the ball and the perpendicular line in the axial direction of the lead screw shaft is a first angle, and the value of the first angle is limited within a range greater than or equal to 50 degrees and less than or equal to 75 degrees; when the ball screw is in the reverse load use state, the angle formed by the intersection of the line connecting the contact point of the ball with the first raceway groove and the center of the current position of the ball and the perpendicular line in the axial direction of the lead screw shaft is a second angle, and the magnitude of the second angle is smaller than the magnitude of the first angle.

5. A ball screw, characterized in that, it includes a lead screw shaft, the outer peripheral surface of the lead screw shaft having a first raceway groove spirally provided in the axial direction of the lead screw shaft; a nut, the inner peripheral surface of the nut having a second raceway groove provided in alignment with the first raceway groove, the nut being sleeved on the lead screw shaft and capable of rotating and shifting in the axial direction of the lead screw shaft; a plurality of balls, the plurality of balls being received between the first raceway groove and the second raceway groove and capable of moving in a rolling manner; and a circulation path, formed by the alignment of the first raceway groove and the second raceway groove and enabling the plurality of balls to circulate within the limits of the circulation path; wherein, there is a height difference between the two side edges of the first raceway groove.

6. The ball screw according to claim 5, characterized in that, the outer wall of the lead screw shaft and the inner wall of the nut have a similar shape, and there is a height difference between the two side edges of the second raceway groove.

7. The ball screw according to claim 5, characterized in that, The first raceway groove spirally forms a first convex portion on the screw shaft along the axial direction of the screw shaft, and the second raceway groove is formed at intervals along the axial direction of the nut to form a second convex portion on the inner wall of the nut; the end faces of the first convex portion and the second convex portion are both flat inclined surfaces with a single slope or non-uniform inclined surfaces with a changing slope.

8. The ball screw according to claim 7, wherein, the first convex portion has an inclined portion continuously extending from the higher side of the first convex portion to the lower side of the first convex portion, and the inclined portion is one of a flat inclined portion, an arc-shaped inclined portion or a stepped inclined portion.

9. The ball screw according to any one of claims 5 to 8, wherein, the ball screw has a forward load use state and a reverse load use state; when the ball screw is in the forward load use state, the line connecting the contact point of the ball and the first raceway groove and the center of the current position of the ball intersects a first included angle with the perpendicular line in the axial direction of the screw shaft, and the value of the first included angle is limited within a range greater than or equal to 50 degrees and less than or equal to 75 degrees; when the ball screw is in the reverse load use state, the line connecting the contact point of the ball and the first raceway groove and the center of the current position of the ball intersects a second included angle with the perpendicular line in the axial direction of the screw shaft, and the magnitude of the second included angle is smaller than the magnitude of the first included angle.

10. An injection molding machine, wherein, it includes the ball screw according to any one of claims 1 to 9.

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