NC roll forming machine
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NACHI FUJIKOSHI CORP
- Filing Date
- 2023-08-30
- Publication Date
- 2026-07-23
AI Technical Summary
【0022】 本発明によれば、簡素な構成でボールねじの伸びによる位相ずれを補正して、高い加工精度で転造加工を行うことができるNC転造盤を提供することができる。
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Abstract
Description
[Technical field]
[0001] The present invention relates to an NC rolling machine that creates a gear shape on a workpiece by rolling. [Background technology]
[0002] A well-known rolling machine has a configuration in which a pair of flat rolling dies (also called forming racks) are pressed against the outer peripheral surface of a workpiece (workpiece) such as a shaft, and rolled, copying the inverse shape of the die surface onto the workpiece and plastically deforming it.
[0003] As an example, in a rolling machine, a pair of flat dies are arranged at point-symmetric positions about the axis of the workpiece, the workpiece is rotatably supported between the flat dies and clamped between them, and the flat dies are moved synchronously relative to one another to plastically process an involute spline or gear on the outer periphery of the workpiece.
[0004] The pair of flat dies is driven by a hydraulic cylinder, a ball screw, a rack and a pinion. Therefore, if the relative phase of the pair of flat dies is shifted at the start of rolling or during rolling, pitch errors occur and processing accuracy decreases. Therefore, the rolling machine is equipped with a synchronizing device that moves the pair of flat dies synchronously relative to each other to prevent the phase shift of the pair of flat dies.
[0005] When the pair of flat dies is driven by a hydraulic cylinder, a rack and a pinion, the synchronizer must place a timing gear at the center of rolling and mechanically connect the pair of flat dies and the timing gear.
[0006] In addition, when driving a pair of flat dies with a ball screw, there are several synchronization devices, such as a method of mechanically connecting the pair of flat dies and the ball screw, or a method of synchronizing the pair of flat dies with numerical control (NC). However, with these methods, heat generated during operation can cause the ball screw to stretch, resulting in a phase shift. For this reason, the rolling machine requires measures against thermal displacement, such as a cooling device or an opposing arrangement of the ball screws.
[0007] In particular, for vertical rolling machines, the left and right rack axes have drive motors located on the top of the machine, and a pair of left and right ball screws are fixed to the top of the machine. However, the origin for control of the left and right rack axes is the upward end of one, and the downward end of the other. For this reason, the left and right rack axes have different lengths from the fixed parts to the origin, and there is also a difference in the amount of elongation due to thermal expansion, resulting in a relative deviation in the origin positions. In the past, measures such as adding a cooling device to cool the ball screws or arranging the drive motors opposite each other (for rack axes with origins at the bottom, the drive motor is arranged at the bottom of the machine) were taken, but these resulted in a complex structure.
[0008] As another measure, the flat die rolling machine of Patent Document 1 is a vertical rolling machine that includes a pair of ball screws, a pair of sliders moved by the pair of ball screws, a pair of flat dies attached to the pair of sliders, a sensor, and a control means. The sensors are provided on the pair of sliders and detect the positions of the pair of flat dies.
[0009] The control means calculates the amount of deviation of the flat dies from the point-symmetrical positional relationship with respect to the axis of the workpiece based on the current position of each slide detected by a sensor installed on each slide, and determines the amount of correction. This deviation is caused by the ball screw stretching due to heat generated by the ball screw. Then, based on the determined amount of correction, the control means changes the relative meshing phase of the gears in the gear box, for example, the phase angle of the helical gear, so that the pair of flat dies are positioned point-symmetrically with respect to the axis of the workpiece. [Prior art documents] [Patent documents]
[0010] [Patent Document 1] JP 2010-52020 A Summary of the Invention [Problem to be solved by the invention]
[0011] However, the flat die rolling machine of Patent Document 1 requires a complex mechanism for changing the phase angle of the helical gear in the gear box, and the gear box itself is expensive, which increases costs.
[0012] In view of these problems, the present invention aims to provide an NC rolling machine that can correct phase shifts caused by elongation of a ball screw with a simple configuration and perform rolling processing with high processing accuracy. [Means for solving the problem]
[0013] In order to solve the above problems, a typical configuration of the NC rolling machine of the present invention is an NC rolling machine that creates a gear shape on a workpiece by rolling, comprising a first ball screw and a second ball screw, a first moving block moved by the first ball screw, a second moving block moved by the second ball screw, a first flat die attached to the first moving block, a second flat die attached to the second moving block, a pair of servo motors that move the first flat die and the second flat die parallel to each other and in opposite directions, a control device that synchronously controls the pair of servo motors, and two sensors that detect the positions of the first moving block and the second moving block before movement, and the control device is characterized in that it corrects the phase of the synchronous control according to the positions of the first moving block and the second moving block detected by the sensors.
[0014] In the above configuration, when the first and second flat dies are moved by the pair of servo motors, the positions of the first and second moving blocks to which the first and second flat dies are attached, respectively, before the start of rolling are detected by two sensors. Then, the control device corrects the phase of the synchronous control of the pair of servo motors, i.e., corrects the phase shift caused by thermal expansion of the ball screw, according to the positions of the first and second moving blocks detected by the sensors.
[0015] As an example, by detecting the position of the first moving block before movement with one sensor and detecting the position of the second moving block before movement with the other sensor, the control device can correct the phase shift caused by the elongation of the ball screw when rolling begins, eliminating the phase shift and starting rolling.
[0016] Therefore, according to the above configuration, with a simple configuration in which two sensors are disposed and the phase is corrected by a control device, the phase shift due to elongation of the ball screw can be corrected and rolling processing can be performed with high processing accuracy.
[0017] When performing reciprocating rolling, the forward rolling is performed by correcting the phase of the synchronous control of the pair of servo motors according to the positions of the first and second moving blocks detected by the one and other sensors at the start of forward rolling. Then, when the return rolling starts, the control device reverses the positions of the first and second moving blocks after the forward rolling and corrects the phase shift caused by the elongation of the ball screw. In this way, forward rolling and return rolling can be performed by correcting the phase of the synchronous control of the pair of servo motors according to the positions of the first and second moving blocks detected by the two sensors.
[0018] The above-mentioned control device is capable of reciprocating rolling, in which the first flat die and the second flat die are moved back and forth to perform rolling, and it is preferable that the control device is equipped with four sensors that detect the positions of the first moving block and the second moving block before they move back and forth.
[0019] As an example, by detecting the position of the first moving block before moving for forward rolling using a specified first sensor, and detecting the position of the second moving block before moving for forward rolling using a specified second sensor, the control device can correct the phase shift due to elongation of the ball screw when forward rolling begins, and can start forward rolling with no phase shift.
[0020] In addition, by detecting the position of the first moving block before moving for return rolling using a specified third sensor, and detecting the position of the second moving block before moving for return rolling using a specified fourth sensor, the control device can correct the phase shift caused by the elongation of the ball screw when return rolling begins, and can start return rolling with no phase shift.
[0021] In this way, by correcting the phase of the synchronous control of a pair of servo motors and performing forward rolling and reverse rolling according to the positions of the first moving block and the second moving block detected by the specified first to fourth sensors, it is possible to perform rolling processing with high precision. Effect of the Invention
[0022] According to the present invention, it is possible to provide an NC rolling machine that can correct phase shift caused by elongation of a ball screw with a simple configuration and perform rolling with high processing accuracy. [Brief description of the drawings]
[0023] [Figure 1] FIG. 1 is a perspective view showing an outline of the configuration of an NC rolling machine according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a main part of the NC rolling machine of FIG. [Diagram 3] FIG. 2 is a functional block diagram of the NC rolling machine of FIG. 1. [Figure 4] 2 is a flowchart showing the operation of the NC rolling machine of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present invention are not shown.
[0025] Fig. 1 is a perspective view showing an outline of the configuration of an NC rolling machine 100 in an embodiment of the present invention. Fig. 2 is a view showing a main part of the NC rolling machine 100 in Fig. 1. The NC rolling machine 100 is a machine tool that performs rolling processing on a workpiece (workpiece 102) shown in Fig. 2.
[0026] 2, the NC rolling machine 100 has a pair of a first flat die (flat die 104a) and a second flat die (flat die 104b), and rolls the workpiece 102 while pressing the flat dies 104a and 104b against the outer circumferential surface of the workpiece 102, copying the inverse shape of the die surface onto the workpiece 102 and plastically deforming it. In this way, the NC rolling machine 100 transfers the gear shape onto the outer periphery of the workpiece 102.
[0027] The NC rolling machine 100 is an example of a vertical rolling machine as shown in FIG. 1. The NC rolling machine 100 is equipped with two rack drive mechanisms 106a, 106b, a work rotation mechanism 108, a headstock drive mechanism 110, and a tailstock drive mechanism 112, and each of these drive mechanisms is controlled by numerical control. Therefore, the NC rolling machine 100 shown in FIG. 1 is a five-axis rolling machine. Note that either the headstock drive mechanism 110 or the tailstock drive mechanism 112 may be a hydraulic or pneumatic cylinder rather than NC controlled, in which case it will be a four-axis NC control.
[0028] The rack driving mechanisms 106a and 106b have a pair of columnar main bodies 114a and 114b facing each other as shown in Fig. 1. The workpiece 102 (see Fig. 2) is located between the rack driving mechanisms 106a and 106b. Note that Fig. 2 shows the main parts of the rack driving mechanisms 106a and 106b in a schematic manner, with the main bodies 114a and 114b omitted.
[0029] 2, the rack drive mechanisms 106a and 106b have a pair of a first ball screw (ball screw 116a) and a second ball screw (ball screw 116b) disposed inside the bodies 114a and 114b, and a pair of a first moving block (moving block 118a) and a second moving block (moving block 118b). The moving blocks 118a and 118b include a pair of ball screw nuts 120a and 120b. The moving blocks 118a and 118b are movably attached to the ball screws 116a and 116b via the ball screw nuts 120a and 120b.
[0030] The flat dies 104a and 104b are attached to the moving blocks 118a and 118b. The flat dies 104a and 104b have a plurality of teeth 122a and 122b on the surfaces facing the workpiece 102.
[0031] The NC rolling machine 100 further includes a pair of servo motors 124a, 124b. Ball screws 116a, 116b are fixed to the servo motors 124a, 124b via a pair of support bearings 126a, 126b. The servo motors 124a, 124b are driven by the supply of electric power, and rotate the ball screws 116a, 116b as independent shafts.
[0032] As a result, the rack drive mechanisms 106a, 106b can move the flat dies 104a, 104b attached to the moving blocks 118a, 118b in parallel and opposite directions to each other by rotating the ball screws 116a, 116b driven by the servo motors 124a, 124b. The X-axis, which is the moving axis of the servo motor 124a, is positive in the downward direction, and the Y-axis, which is the moving axis of the servo motor 124b, is positive in the upward direction.
[0033] The rack drive mechanisms 106a, 106b move the flat dies 104a, 104b parallel to each other and in opposite directions, and further move them back and forth multiple times, thereby pressing the teeth 122a, 122b of the flat dies 104a, 104b against the outer peripheral surface of the workpiece 102 while rolling them, thereby enabling the rolling process to be performed in stages (in multiple passes).
[0034] When performing forward rolling, the movable block 118a moves down along the X-axis from the position shown in Fig. 2 (the start position of forward rolling) to the position shown by the two-dot chain line C in the figure. The movable block 118b moves up along the Y-axis from the position shown in Fig. 2 (the start position of forward rolling) to the position shown by the two-dot chain line D in the figure.
[0035] When performing reverse rolling, the movable block 118a moves up along the X-axis from the position indicated by the two-dot chain line C in Fig. 2 (the start position of reverse rolling) and moves again to the start position of forward rolling. The movable block 118b moves down along the Y-axis from the position indicated by the two-dot chain line D in Fig. 2 (the start position of reverse rolling) and moves again to the start position of forward rolling.
[0036] When performing reciprocating rolling on the NC rolling machine 100, the movable blocks 118a, 118b are moved as described above, so that the teeth 122a, 122b of the flat dies 104a, 104b are simultaneously pressed against the outer peripheral surface of the workpiece 102 from above and below, thereby creating a gear shape in the workpiece 102.
[0037] The workpiece rotation mechanism 108 shown in FIG. 1 has a servo motor (not shown), which rotates the workpiece 102 along the C-axis, which is the rotation direction around the Z-axis in the figure, in synchronization with the vertical movement of the flat dies 104a, 104b by the rack drive mechanisms 106a, 106b.
[0038] The headstock driving mechanism 110 has a headstock (not shown) supported so as to be movable along the Z-axis direction, and a servo motor 128. In the headstock driving mechanism 110, the headstock moves along the Z-axis direction, i.e., the axial direction of the workpiece 102, by being driven by the servo motor 128, and further supports the workpiece 102 so as to be rotatable.
[0039] The tailstock drive mechanism 112 has a tailstock 130 supported so as to be movable along the W-axis direction in the figure, and a servo motor 132. The tailstock 130 is disposed opposite the headstock, and is moved along the axial direction of the workpiece 102 by the servo motor 132, and then comes into contact with the workpiece 102.
[0040] In the NC rolling machine 100, the heat generated by the ball screws 116a, 116b during operation may cause the ball screws 116a, 116b to stretch, changing the axial positions of the moving blocks 118a, 118b and shifting the initial positions of the rolling operation. If the initial positions of the rolling operation are shifted, the teeth 122a, 122b of the flat dies 104a, 104b cannot be pressed against the outer peripheral surface of the workpiece 102 from above and below at the same time when performing reciprocating rolling, and the processing accuracy decreases.
[0041] In particular, since the NC rolling machine 100 is a vertical rolling machine, as shown in FIG. 2, one origin A of the rack shaft of the rack drive mechanisms 106a and 106b is the upward end side in terms of control, and the other origin B is the downward end side. For this reason, the rack shaft has different lengths from the support bearings 126a and 126b, which are fixed parts that serve as the basis for the elongation of the ball screws 116a and 116b, to the origins A and B. As a result, the elongation amounts of the ball screws 116a and 116b due to thermal expansion also differ, resulting in a relative deviation of the origin positions. Note that, of the rack drive mechanisms 106a and 106b, the one with the longer length from the fixed part to the origin, i.e., the elongation amount of the ball screw 116b of the rack drive mechanism 106b, is greater than the elongation amount of the ball screw 116a of the rack drive mechanism 106a.
[0042] Therefore, the NC rolling machine 100 of this embodiment employs a configuration that can correct the phase shift caused by the thermal expansion of the ball screws 116a, 116b and perform rolling processing with high processing accuracy on the workpiece 102. This will be described in detail below.
[0043] The NC rolling machine 100 includes an X-axis rearward end sensor (hereinafter, first sensor 134a), a Y-axis rearward end sensor (hereinafter, second sensor 134b), an X-axis forward end sensor (hereinafter, third sensor 134c), and a Y-axis forward end sensor (hereinafter, fourth sensor 134d) shown in Fig. 2. Each of the sensors 134a to 134d is a magnetic sensor (e.g., a Hall element) that detects the position of the moving blocks 118a and 118b before they are moved for rolling.
[0044] The first sensor 134a detects the position of one of the moving blocks 118a before moving to perform forward rolling (start position of forward rolling). The second sensor 134b detects the position of the other moving block 118b before moving to perform forward rolling (start position of forward rolling). The third sensor 134c detects the position of the moving block 118a shown by the two-dot chain line C in the figure before moving to perform return rolling (start position of return rolling). The fourth sensor 134d detects the position of the moving block 118b shown by the two-dot chain line D in the figure before moving to perform return rolling (start position of return rolling).
[0045] Also, magnetic bodies are disposed near the ball screw nuts 120a, 120b of the moving blocks 118a, 118b. Therefore, the first sensor 134a and the third sensor 134c are disposed near the ball screw nut 120a of the moving block 118a and detect the magnetic bodies using magnetic sensors. Also, the second sensor 134b and the fourth sensor 134d are disposed near the ball screw nut 120b of the moving block 118b and detect the magnetic bodies using magnetic sensors.
[0046] Fig. 3 is a functional block diagram of the NC rolling machine 100 in Fig. 1. The NC rolling machine 100 is equipped with a control device 138. The control device 138 controls the operation of the NC rolling machine 100. The control device 138 has a numerical control unit 140, a servo control unit 142, and a phase shift calculation unit 144. Note that the phase is the rotational phase of the ball screws 116a, 116b, that is, it is converted into the positions of the moving blocks 118a, 118b.
[0047] The positional deviation calculation unit 144 calculates the phase deviation due to the elongation of the ball screws 116a, 116b at the start of forward rolling based on the start positions of the forward rolling of the moving blocks 118a, 118b before moving to forward roll detected by the first sensor 134a and the second sensor 134b. The positional deviation calculation unit 144 also calculates the phase deviation due to the elongation of the ball screws 116a, 116b at the start of return rolling based on the start positions of the return rolling of the moving blocks 118a, 118b before moving to return roll detected by the third sensor 134c and the fourth sensor 134d.
[0048] The numerical control unit 140 calculates a correction amount for the servo motors 124a, 124b so as to correct the phase shift due to the elongation of the ball screws 116a, 116b at the start of reciprocating rolling calculated by the position shift calculation unit 144, and outputs this correction amount to the servo control unit 142. The servo control unit 142 outputs the correction amount output from the numerical control unit 140 to the servo motors 124a, 124b as a drive signal, and corrects the phase of the synchronous control of the servo motors 124a, 124b.
[0049] In this way, the control device 138 adjusts the initial position of the rolling operation (calibrates the rolling start position) by correcting the phase of the synchronous control according to the positions of the moving blocks 118a, 118b detected by the sensors 134a to 134d. That is, the control device 138 synchronously controls the servo motors 124a, 124b to change the phase of the ball screws 116a, 116b and corrects the axial positions of the moving blocks 118a, 118b, thereby making it possible to press the teeth 122a, 122b of the flat dies 104a, 104b against the outer circumferential surface of the workpiece 102 from above and below at the same time.
[0050] Fig. 4 is a flowchart showing the operation of the NC rolling machine 100 in Fig. 1. First, in the NC rolling machine 100, the first sensor 134a detects the forward rolling start position of the moving block 118a before forward rolling (step S100), and the second sensor 134b detects the forward rolling start position of the moving block 118b before forward rolling (step S102).
[0051] Next, the control device 138 corrects the phase shift caused by the elongation of the ball screws 116a, 116b at the start of forward rolling based on the forward rolling start positions of the moving blocks 118a, 118b detected by the first sensor 134a and the second sensor 134b, and performs forward rolling (step S104).
[0052] If the re-rolling is to be performed subsequently (step S106, Yes), the third sensor 134c detects the re-rolling start position of the moving block 118a before the re-rolling (step S108), and the fourth sensor 134d detects the re-rolling start position of the moving block 118b before the re-rolling (step S110). On the other hand, if the re-rolling is not to be performed in step S106 (No), the rolling process is terminated.
[0053] Next, the control device 138 corrects the phase shift caused by the elongation of the ball screws 116a, 116b at the start of the return rolling based on the return rolling start positions of the moving blocks 118a, 118b detected by the third sensor 134c and the fourth sensor 134d, and performs the return rolling (step S112). If the forward rolling is not to be performed further (step S114, No), the rolling process is terminated, and if the forward rolling is to be continued (Yes), the process of the above step S100 is performed again.
[0054] In this manner, in the NC rolling machine 100, the phase shift caused by the elongation of the ball screws 116a, 116b is corrected according to the positions of the moving blocks 118a, 118b detected by each of the sensors 134a to 134d, and forward and reverse rolling is performed, thereby enabling rolling processing to be performed with high precision.
[0055] Furthermore, the NC rolling machine 100 has a simple configuration in which the sensors 134a to 134d are disposed and the control device 138 corrects the phase of the synchronous control of the servo motors 124a and 124b, and thus it is possible to perform rolling processing with high processing accuracy, thereby suppressing increases in costs.
[0056] In the above-mentioned NC rolling machine 100, the first sensor 134a, the second sensor 134b, the third sensor 134c, and the fourth sensor 134d are arranged, but this is not limited to this, and a simpler configuration may be achieved by arranging only the first sensor 134a and the second sensor 134b.
[0057] In such a case, the control device 138 performs forward rolling by correcting the phase of the synchronous control of the servo motors 124a and 124b according to the positions of the moving blocks 118a and 118b detected by the first sensor 134a and the second sensor 134b at the start of forward rolling. Then, at the start of reverse rolling, the control device 138 may consider the position of the moving block 118a after forward rolling to be the opposite to the position of the moving block 118b, and correct the phase shift due to the elongation of the ball screws 116a and 116b. In this way, forward rolling and reverse rolling can be performed by correcting the phase of the synchronous control of the servo motors 124a and 124b according to the positions of the moving blocks 118a and 118b detected by the first sensor 134a and the second sensor 134b.
[0058] Furthermore, the above-mentioned NC rolling machine 100 may have a simpler configuration by arranging only the second sensor 134b. In such a case, the control device 138 calculates the elongation of the ball screw 116b according to the position of the moving block 118b detected by the second sensor 134b at the start of forward rolling. The control device 138 also calculates the elongation of the ball screw 116a based on the difference in length from the support bearings 126a, 126b on the rack shaft to the origins A, B on the control.
[0059] Furthermore, the control device 138 calculates the phase shift caused by the elongation of the ball screws 116a, 116b, and performs forward rolling by correcting the phase of the synchronous control of the servo motors 124a, 124b to correct this phase shift. Then, when starting the reverse rolling, the control device 138 regards the position of the moving block 118a after the forward rolling as being the opposite to the position of the moving block 118b, and corrects the phase shift caused by the elongation of the ball screws 116a, 116b.
[0060] In this way, the phase of the synchronous control of the servo motors 124a, 124b can be corrected according to the position of the moving block 118b detected by the second sensor 134b to perform forward and reverse rolling, thereby further simplifying the configuration.
[0061] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an example. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that such examples also naturally belong to the technical scope of the present invention. [Industrial Applicability]
[0062] The present invention can be used as an NC rolling machine that creates a gear shape on a workpiece by rolling. [Explanation of symbols]
[0063] 100...NC rolling machine, 102...work, 104a, 104b...flat die, 106a, 106b...rack drive mechanism, 108...work rotation mechanism, 110...headstock drive mechanism, 112...tailstock drive mechanism, 114a, 114b...main body, 116a, 116b...ball screw, 118a, 118b...moving block, 120a, 120b...ball screw nut, 122a, 122b...flat die tooth, 124a, 124b, 128, 132...servo motor, 126a, 126b...support bearing, 130...tailstock, 134a...first sensor, 134b...second sensor, 134c...third sensor, 134d...fourth sensor, 138...control device, 140...numerical control unit, 142...servo control unit, 144...phase shift calculation unit
Claims
1. In an NC thread rolling machine that creates gear shapes on a workpiece by thread rolling, First ball screw and second ball screw, A first moving block that moves by the first ball screw, A second moving block that moves by the second ball screw, The first flat die attached to the first moving block, The second flat die attached to the second moving block, A pair of servo motors that move the first flat die and the second flat die parallel to each other and in opposite directions, A control device for synchronously controlling the pair of servo motors, The system includes two sensors that detect the positions of the first moving block and the second moving block before they move, The control device is characterized by correcting the phase of the synchronous control according to the positions of the first moving block and the second moving block detected by the sensor, in an NC thread rolling machine.
2. The control device is capable of reciprocating rolling, which involves moving the first flat die and the second flat die back and forth, The NC thread rolling machine according to claim 1, further comprising four sensors for detecting the position of the first moving block and the second moving block before their respective reciprocating movements.