NC thread rolling machine
The NC thread rolling machine addresses the issue of deformation in thin-walled hollow materials by synchronizing rack movement and height adjustments, ensuring precise rolling and consistent tooth formation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NACHI FUJIKOSHI CORP
- Filing Date
- 2024-10-25
- Publication Date
- 2026-05-13
Smart Images
Figure 2026077203000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a numerical control (NC) swaging machine for swaging workpieces.
Background Art
[0002] A swaging machine is a machine tool that rolls while pressing a pair of racks (also called flat dies for swaging) against the outer peripheral surface of a workpiece (work), such as a shaft-like part like a shaft, and transfers the reverse shape of the rack surface onto the workpiece to cause plastic deformation.
[0003] For example, Patent Document 1 describes a swaging flat die and a swaging method. In this swaging flat die, uneven portions of substantially constant shape corresponding to the workpiece are provided continuously in the longitudinal direction at regular intervals. Further, the swaging flat die is provided with a finishing portion, an adjusting portion, and a biting portion (relief portion).
[0004] The finishing portion is provided at the center of the swaging flat die, and the height of the uneven portions from the die reference surface is constant. The adjusting portion is provided on both sides of the finishing portion, and the height of the uneven portions gradually decreases outward. The biting portion (relief portion) is further outward following each adjusting portion, and the height of the uneven portions decreases with the same gradient as that of the adjusting portion, and further, the surface of the uneven portions is roughened by blast shots.
[0005] In the swaging method of Patent Document 1, in a swaging machine having this swaging flat die, the workpiece is reciprocally swaged while gradually reducing the distance between the pair of swaging flat dies when the workpiece is positioned in the relief portion.
Prior Art Documents
Patent Documents
[0006]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0007] Incidentally, motor shafts used in EVs and other applications require miniaturization and weight reduction, and sometimes thin-walled hollow materials are subjected to rolling. In Patent Document 1, the rolling process is carried out multiple times, gradually reducing the distance between a pair of rolling dies and bringing the rolling dies closer to the workpiece.
[0008] However, Patent Document 1 describes a problem in which, when a thin-walled hollow material is rolled, the workpiece deforms into an elliptical shape, resulting in a deterioration of processing accuracy. When the workpiece deforms into an elliptical shape, not only is the workpiece elliptical in shape upon completion of processing, but the material also escapes, making it difficult to achieve sufficient tooth height (the tooth grooves become shallower).
[0009] In view of these problems, the present invention aims to provide an NC rolling machine that can perform rolling on hollow materials with high processing accuracy. [Means for solving the problem]
[0010] To solve the above problems, a typical configuration of the NC thread rolling machine according to the present invention is an NC thread rolling machine that rolls a gear shape onto a workpiece using a pair of racks, comprising two rack drive mechanisms that move the racks in parallel and opposite directions to each other, and that advance or retract the racks, and a control unit that controls the operation of the rack drive mechanisms, wherein the control unit controls the operation of the rack drive mechanisms to roll the workpiece by repeatedly advancing the racks by a predetermined feed amount and retracting them by a predetermined return amount less than the feed amount.
[0011] The system further comprises two rack height adjustment mechanisms that move the racks in parallel and perpendicular directions toward and away from each other, thereby raising or lowering the rack height. Preferably, when the rack is retracted, the control unit controls the operation of the rack height adjustment mechanisms to raise the rack height in synchronization with the retraction of the rack so that there is no gap between the rack teeth and the workpiece.
[0012] When the control unit described above moves the rack forward again after it has been moved backward, it is preferable to control the operation of the rack height adjustment mechanism and lower the rack height in synchronization with the forward movement of the rack so that the rack teeth do not engage with the workpiece until the rack reaches the forward position it was in just before it moved backward. [Effects of the Invention]
[0013] According to the present invention, it is possible to provide an NC rolling machine that can perform rolling on hollow materials with high processing accuracy. [Brief explanation of the drawing]
[0014] [Figure 1] This is a perspective view showing an overview of the configuration of an NC thread rolling machine in an embodiment of the present invention. [Figure 2] Figure 1 shows the main components of the NC thread rolling machine. [Figure 3] This is a diagram of the rack shown in Figure 2. [Figure 4] This is a schematic diagram showing the process of rolling a workpiece. [Figure 5] Figure 4 is a graph showing the relationship between the amount of workpiece adjustment and the operation of the rack. [Modes for carrying out the invention]
[0015] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely examples to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.
[0016] FIG. 1 is a perspective view showing an outline of the configuration of an NC rotary forging machine 100 according to an embodiment of the present invention. FIG. 2 is a view showing a main part of the NC rotary forging machine 100 of FIG. 1. The NC rotary forging machine 100 is a machine tool for rotary forging a gear on a workpiece (workpiece 102) shown in FIG. 2.
[0017] The NC rotary forging machine 100 includes a pair of racks 104 shown in FIG. 2, and rolls the workpiece 102 while pressing the racks 104 against the outer peripheral surface of the workpiece 102, and transfers and plastically deform the reverse shape of the rack surface onto the workpiece 102. In this way, the NC rotary forging machine 100 transfers a gear shape to the outer periphery of the workpiece 102.
[0018] The workpiece 102 is a shaft-like component such as a shaft. In particular, a motor shaft used in an EV or the like is required to be small and lightweight, and is a hollow thin-walled shaft. Therefore, the workpiece 102 includes not only solid shaft-like components but also shaft-like components made of thin-walled hollow materials. When rotary forging such a thin-walled hollow material workpiece 102, a load is applied to the circular workpiece 102, and the workpiece 102 may deform into an elliptical shape, deteriorating the processing accuracy.
[0019] Therefore, the NC rotary forging machine 100 of the present embodiment adopts a configuration that can perform rotary forging on the workpiece 102 with high processing accuracy even when the workpiece 102 is a thin-walled hollow material. This will be specifically described below.
[0020] The NC forging machine 100 is an example of a vertical forging machine as shown in FIG. 1. The NC forging machine 100 includes two rack drive mechanisms 106a and 106b, two rack height adjustment mechanisms 108a and 108b, a work rotation mechanism 110, a headstock drive mechanism 112, and a tailstock drive mechanism 114, and each of these drive mechanisms is controlled by numerical control by a control unit 115. For this reason, the NC forging machine 100 shown in FIG. 1 is a seven-axis forging machine. Note that one of the headstock drive mechanism 112 or the tailstock drive mechanism 114 may be a hydraulic or pneumatic cylinder instead of NC control, and in that case, it will be a six-axis NC control. Also, here, the NC forging machine 100 equipped with the work rotation mechanism 110 by NC control is illustrated, but it is not limited to this. The NC forging machine 100 may not include the work rotation mechanism 110 itself, and in this case, it will be a six-axis forging machine. Note that when fixing a headstock not shown in the figure, it will be a four-axis NC control.
[0021] As shown in FIG. 2, the rack drive mechanisms 106a and 106b face each other. Also, a work 102 is positioned between the rack drive mechanisms 106a and 106b. Further, between the rack drive mechanisms 106a and 106b and the work 102, rack height adjustment mechanisms 108a and 108b that face each other with the work 102 in between are arranged.
[0022] As shown in FIG. 2, in the rack drive mechanisms 106a and 106b, a pair of ball screws 118a and 118b are arranged inside a pair of columnar bodies 116a and 116b. A pair of moving blocks 122a and 122b are movably attached to the ball screws 118a and 118b.
[0023] The servo motors 120a and 120b are driven by the supply of power, and rotate the ball screws 118a and 118b as independent axes. As a result, the rack drive mechanisms 106a and 106b can move the moving blocks 122a and 122b in parallel and opposite directions by rotating the ball screws 118a and 118b driven by the servo motors 120a and 120b. The X-axis, which is the movement axis of servo motor 120a, is positive downwards, and the Y-axis, which is the movement axis of servo motor 120b, is positive upwards.
[0024] The rack height adjustment mechanisms 108a and 108b have a pair of tables 124a and 124b as shown in Figure 2. The tables 124a and 124b are fixed to the moving blocks 122a and 122b of the rack drive mechanisms 106a and 106b. Furthermore, the rack height adjustment mechanisms 108a and 108b have a pair of ball screws 126a and 126b, a pair of servo motors 128a and 128b (U-axis and V-axis), and a pair of wedge mechanisms 130a and 130b.
[0025] The wedge mechanisms 130a and 130b each include wedges 132a and 132b and slots 134a and 134b, respectively, and these components are combined with each other to produce a wedge action (orthogonal transformation of the direction of movement).
[0026] Racks 104 are fixed to the pieces 134a and 134b of the wedge mechanisms 130a and 130b. In this way, racks 104 are fixed to tables 124a and 124b via the wedge mechanisms 130a and 130b.
[0027] The wedges 132a and 132b of the wedge mechanisms 130a and 130b are connected to ball screws 126a and 126b. Therefore, when servo motors 128a and 128b rotate the ball screws 126a and 126b as independent axes, the wedges 132a and 132b can move vertically as shown by arrows Ea-Fa and Eb-Fb. As a result, the tops 134a and 134b can move horizontally as shown by arrows Ga-Ha and Gb-Hb.
[0028] This allows the rack height adjustment mechanisms 108a and 108b to move the racks 104 fixed to the slots 134a and 134b toward and toward each other. The toward and toward direction is the direction in which the racks 104 move toward and toward each other while maintaining their opposing positions, and is perpendicular to the parallel direction described above by the rack drive mechanisms 106a and 106b. Therefore, the rack height adjustment mechanisms 108a and 108b can change the distance between the racks 104.
[0029] Figure 3 shows the rack 104 in Figure 2. As shown in Figure 2, the rack 104 has a plurality of teeth 136 on the surface facing the workpiece 102. In this embodiment, the teeth 136 of the rack 104 are provided with a gradient.
[0030] Specifically, the teeth 136 of the rack 104 include gripping teeth (gripping portion 138), adjustment teeth (adjustment portion 140), finishing teeth (finishing portion 142), and relief teeth (relief portion 144), which are arranged sequentially from one end 146 to the other end 148 of the rack 104.
[0031] The teeth height of the gripping portion 138 of the rack 104 gradually increases from one end 146 to the other end 148. The gripping portion 138 is sandblasted to roughen its surface in order to improve grip on the workpiece 102.
[0032] Furthermore, the teeth 136 of the rack 104 gradually increase in height from the engagement portion 138 towards the adjustment portion 140. The finishing portion 142 has a constant tooth height. The relief portion 144 gradually decreases in height towards the other end 148.
[0033] The workpiece rotation mechanism 110 shown in Figure 1 has a servo motor (not shown) and rotates the workpiece 102 along the C axis, which is the rotational direction around the Z axis in the figure, in synchronization with the vertical movement of the rack 104 by the rack drive mechanisms 106a and 106b. Note that the NC rolling machine 100 may be configured without the workpiece rotation mechanism 110 itself.
[0034] The headstock drive mechanism 112 includes a headstock (not shown) supported to be movable along the Z-axis direction, and a servo motor 150. The headstock drive mechanism 112 moves the headstock along the Z-axis direction, i.e., the axis direction of the workpiece 102, when driven by the servo motor 150, and further supports the workpiece 102 in a rotatable manner.
[0035] The tailstock drive mechanism 114 includes a tailstock 152 supported to be movable along the W-axis direction in the figure, and a servo motor 154. The tailstock 152 is positioned opposite the headstock and is moved along the axial direction of the workpiece 102 by the servo motor 154, and further contacts the workpiece 102. As a result, the headstock drive mechanism 112 and the tailstock drive mechanism 114 rotatably support both ends of the workpiece 102 and shift the workpiece 102 in the axial direction.
[0036] As shown in Figure 2, the rack drive mechanisms 106a and 106b move the rack 104 in parallel and opposite directions, causing the rack 104 to advance (see arrows Ea and Eb) or move backward (see arrows Fa and Fb). The rack height adjustment mechanisms 108a and 108b move the rack 104 in a parallel and perpendicular direction, causing the height of the rack 104 to increase (see arrows Ga and Gb) or decrease (see arrows Ha and Hb). Note that when the rack height increases, the rack 104 moves closer together, and when the rack height decreases, it widens.
[0037] The NC rolling machine 100 includes a control unit 115 (see Figure 1) that controls the operation of the rack drive mechanisms 106a, 106b and the rack height adjustment mechanisms 108a, 108b. The control unit 115 rolls the workpiece 102 by moving the rack 104 forward or backward and raising or lowering the rack height.
[0038] The operation of the NC thread rolling machine 100 during the rolling process will be explained below with reference to Figures 4 and 5. Figure 4 is a schematic diagram showing the rolling process of a workpiece 102. Figure 5 is a graph showing the relationship between the amount of pressure applied to the workpiece 102 in Figure 4 and the operation of the rack 104. The "amount of pressure applied" by the rack 104 shown in Figure 5 refers to the amount (depth) to which the outer surface of the workpiece 102 is pressed by the gripping portion 138 and adjustment portion 140 of the rack 104, which are provided with a gradient.
[0039] At the rolling start timing Ta shown in Figure 5, the rack 104 is initially in a state where the gripping portion 138 formed near one end 146 of the rack 104 is in contact with the outer circumferential surface of the workpiece 102, as shown in Figure 4(a).
[0040] At timings Ta to Tb in Figure 5, the control unit 115 then controls the operation of the rack drive mechanisms 106a and 106b to advance the rack 104 by a predetermined amount (for example, half a rotation of the workpiece) as shown by arrows Ea and Eb in Figure 4(b). Let P be the advanced position at this time. As a result, the rack 104 presses the gripping portion 138 against the outer circumferential surface of the workpiece 102, causing the workpiece 102 to rotate half a rotation (see arrow J).
[0041] As the workpiece 102 rotates half a turn, the presence of racks 104 on both sides ensures that the entire circumference of the workpiece 102 is subjected to rolling. It is expected that this forward movement will deform the workpiece 102 into an ellipse.
[0042] At timings Tb to Tc in Figure 5, the control unit 115 then controls the operation of the rack drive mechanisms 106a and 106b to move the rack 104 backward as shown by arrows Fa and Fb in Figure 4(c), while also controlling the operation of the rack height adjustment mechanisms 108a and 108b.
[0043] Specifically, the control unit 115 raises the rack height in synchronization with the retraction of the rack 104, as shown by arrows Ga and Gb in Figure 4(c). This prevents a gap from forming between the gripping portion 138 of the rack 104 and the workpiece 102, thereby suppressing slippage between them. At this time, the control unit 115 rotates the workpiece 102 by half a turn in synchronization with the retracting rack 104 (see arrow K). Note that the control of the control unit 115 is not limited to NC control.
[0044] At timings Tb to Tc in Figure 5, the rack 104 retracts by a predetermined amount (in this case, by half a rotation of the workpiece 102), so the workpiece 102 is not pushed in, but rather leveled as shown in Figure 5. By leveling the workpiece 102, even if the thin-walled hollow material of the workpiece 102 is pushed in and distorted into an ellipse at timings Ta to Tb, the shape of the workpiece 102 can be returned from an ellipse to a perfect circle at timings Tb to Tc.
[0045] Between timings Tc and Td in Figure 5, the control unit 115 further controls the operation of the rack drive mechanisms 106a and 106b to move the rack 104 forward again, as shown by arrows Ea and Eb in Figure 4(d), while also controlling the operation of the rack height adjustment mechanisms 108a and 108b.
[0046] Specifically, the control unit 115 lowers the rack height in synchronization with the forward movement of the rack 104, as shown by arrows Ha and Hb in Figure 4(d). In this way, the gripping portion 138 of the rack 104 is prevented from forcing the workpiece 102 until the position of the rack 104, which moves forward again between timings Tc and Td, reaches the forward position P of the rack 104 just before it moves backward, as shown by timing Tb in Figure 5. At this time, the control unit 115 rotates the workpiece 102 by half a turn using the forward-moving rack 104 (see arrow L).
[0047] At timing Td in Figure 5, the position of rack 104 returns to the forward position P at timing Tb, and the rack height also returns to the rack height at timing Tb. In other words, rack 104 returns to the position and rack height immediately after the workpiece 102 was previously driven in and rolled.
[0048] Furthermore, since the gripping portion 138 of the rack 104 does not press against the workpiece 102 during the timings Tc to Td, the workpiece 102 can be leveled from the timings Tb to Tc onward. Therefore, by leveling the workpiece 102 during the timings Tb to Td shown in Figure 5, the shape of the workpiece 102 can be reliably returned from an ellipse to a perfect circle.
[0049] Between timings Td and Te in Figure 5, the control unit 115 controls the operation of the rack drive mechanisms 106a and 106b to further advance the rack 104 as shown by arrows Ea and Eb in Figure 4(e). This causes the rack 104 to press the gripping portion 138 against the outer circumferential surface of the workpiece 102 again, while rotating the workpiece 102 by half a turn (see arrow M). This restarts the rolling process of the workpiece 102. In other words, by combining timings Tc-Td and Td-Te, the workpiece 102 is rotated one full turn. Therefore, the advanced position becomes 2P.
[0050] Subsequently, as shown in Figure 5, the control unit 115 repeatedly moves backward by half a rotation and forward by one rotation between timings Te and Tf. In this way, the control unit 115 repeatedly moves the rack 104 forward by a predetermined feed amount and backward by a predetermined return amount less than the feed amount, thereby rolling the workpiece 102 using the gripping portion 138 and adjustment portion 140 of the rack 104.
[0051] From timing Tf shown in Figure 5, that is, when the rack 104 approaches the finishing section 142, the control unit 115 simply moves the rack 104 forward. As a result, the rack 104 finishes the workpiece 102 with the finishing section 142. As the rack 104 moves further forward, the relief section 144, whose tooth height gradually decreases, separates the rack 104 from the workpiece 102, and the rolling process can be completed.
[0052] Therefore, with the NC thread rolling machine 100, even if the thin-walled hollow material workpiece 102 is distorted into an ellipse, the workpiece 102 is gradually rolled while being carefully returned to a perfect circle, thus enabling thread rolling of thin-walled hollow materials with high processing accuracy.
[0053] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]
[0054] This invention can be used as an NC rolling machine for rolling workpieces. [Explanation of Symbols]
[0055] 100...NC thread rolling machine, 102...Workpiece, 104...Rack, 106a, 106b...Rack drive mechanism, 108a, 108b...Rack height adjustment mechanism, 110...Workpiece rotation mechanism, 112...Headstock drive mechanism, 114...Tailstock drive mechanism, 115...Control unit, 116a, 116b...Main unit, 118a, 118b, 126a, 126b...Ball screw, 120a, 120b, 128a, 1 28b, 150, 154... Servo motor, 122a, 122b... Moving block, 124a, 124b... Table, 130a, 130b... Wedge mechanism, 132a, 132b... Wedge, 134a, 134b... Spinner, 136... Rack teeth, 138... Engagement part, 140... Adjustment part, 142... Finishing part, 144... Relief part, 146... One end of rack, 148... Other end of rack, 152... Tailstock
Claims
1. In an NC rolling machine that rolls gear shapes onto a workpiece using a pair of racks, Two rack drive mechanisms move the racks parallel to each other and in opposite directions, and move the racks forward or backward. The system comprises a control unit that controls the operation of the rack drive mechanism, The control unit controls the operation of the rack drive mechanism to repeatedly move the rack forward by a predetermined feed amount and backward by a predetermined return amount less than the feed amount, thereby performing a rolling process on the workpiece.
2. The system further comprises two rack height adjustment mechanisms that move the racks toward and toward each other in directions perpendicular to the parallel direction, thereby raising or lowering the height of the racks. The NC thread rolling machine according to claim 1, characterized in that when the rack is retracted, the control unit controls the operation of the rack height adjustment mechanism to raise the rack height in synchronization with the retraction of the rack so that there is no gap between the teeth of the rack and the workpiece.
3. The NC thread rolling machine according to claim 2, characterized in that when the control unit moves the rack forward again after it has been moved backward, it controls the operation of the rack height adjustment mechanism and lowers the rack height in synchronization with the forward movement of the rack so that the teeth of the rack do not engage with the workpiece until the rack reaches the forward position of the rack just before it was moved backward.