Pallet exchanging apparatus

Abstract

A pallet exchanging apparatus (130) for a machine tool for exchanging pallets by using a turning arm has: a turning drive device (138) capable of switching a turning command speed to a different value during turning of a turning arm (132); a graphical user interface screen (200) for setting a phase to switch the turning command speed of the turning arm; and a control device (150) for switching the turning command speed of the turning drive device (138) in accordance with the phase set on the graphical user interface screen.

Description

Pallet exchange device

[0001] The present invention relates to a pallet exchange device used together with a machine tool or a workpiece cleaning device.

[0002] There are various types of pallet exchange devices that exchange a pallet with a machined workpiece attached for a pallet with an unmachined workpiece attached, but a widely used type of pallet exchange device involves placing a pallet with a machined workpiece attached on one end of a rotating arm and a pallet with an unmachined workpiece attached on the other end, and rotating the rotating arm 180 degrees around a vertical axis to exchange pallets.

[0003] To increase the productivity of machine tools, it is preferable to shorten the time required for pallet exchange. However, the pallet exchange speed is limited by factors such as the driving force required to rotate the rotating arm and the centrifugal force required to prevent the pallet and workpiece from tipping over, and is generally fixed at a single speed calculated based on these limitations. Patent Document 1 describes a pallet exchange device that uses strain gauges to measure the weight of workpieces of various weights and changes the rotation speed during pallet movement depending on the weight of each individual workpiece, thereby shortening the pallet exchange time.

[0004] Japanese Patent Application Laid-Open No. 2004-276162

[0005] In such a pallet exchange device equipped with a swivel arm, the rotation of the swivel arm during a pallet exchange operation causes coolant adhering to components that rotate with the swivel arm, such as the machined workpiece, pallet, and swivel door, to scatter. Since the scattered coolant contaminates the area around the pallet exchange device, preventing the splattering of coolant can be important. However, in the pallet exchange device of Patent Document 1, the swivel arm rotates at high speed when the workpiece is light, scattering a large amount of coolant over a wide area around the pallet exchange device. Rotating the swivel arm at a slow speed reduces the splattering of coolant, but this increases the pallet exchange time, resulting in a problem of reduced machine productivity.

[0006] The technical objective of the present invention is to solve these problems of the conventional technology, and to provide a pallet changing device that reduces the scattering of coolant during pallet changing without increasing the time required for rotating pallet changing as much as possible.

[0007] In order to solve the above-mentioned problems, according to the present invention, there is provided a pallet exchange device for a machine tool that exchanges pallets using a swivel arm, comprising: a swivel drive device that can switch a swivel command speed to different values ​​while the swivel arm is rotating; a phase setting device that sets a phase for switching the swivel command speed of the swivel arm; and a control device that switches the swivel command speed of the swivel drive device in accordance with the phase set by the phase setting device.

[0008] According to the present invention, the rotation command speed is switched using the phase set by the phase setting device, so that the section in which coolant scattering can be prevented by rotating the rotation arm at a low speed is limited, making it possible to effectively suppress coolant scattering without significantly increasing the pallet replacement time.

[0009] Fig. 6 is a schematic side view showing an example of a machine tool to which the present invention is applied; Fig. 7 is a schematic plan view of the machine tool of Fig. 1; Fig. 8 is a block diagram showing a swing drive device that swings a swing arm; Fig. 9 is a graph showing the relationship between swing speed and pallet exchange time; Fig. 10 is a schematic view of a graphical user interface displayed on a display device; Fig. 11 is a block diagram showing another example of a swing drive device; Fig. 12 is a block diagram showing an example of a hydraulic supply device used in the swing drive device of Fig. 6; Fig. 13 is a schematic plan view showing another example of a machine tool to which the present invention is applied.

[0010] A preferred embodiment of the present invention will now be described with reference to the accompanying drawings. Referring to Figures 1 and 2, which show an example of a machine tool to which the present invention is applicable, machine tool 100 includes a bed 102 as a base fixed to the factory floor. A Z-axis slider 112 is provided on the upper surface of the front portion (left side in Figures 1 and 2) of bed 102 so as to be reciprocable along a pair of Z-axis guide rails 102b extending in the front-rear direction or Z-axis direction (left-right direction in Figures 1 and 2). A rotary table 114 is provided on Z-axis slider 112 so as to be rotatable in the B-axis direction around a vertical axis. The rotary table 114 includes a B-axis servo motor (not shown) as a B-axis feed device that rotates and feeds the rotary table 114 in the B-axis direction.

[0011] A column 104 is provided on the upper surface of the rear portion (right side in FIGS. 1 and 2) of the bed 102 so as to be reciprocable along a pair of X-axis guide rails 102a extending in the left-right direction or the X-axis direction (a direction perpendicular to the plane of the paper in FIG. 1, and a vertical direction in FIG. 2). A Y-axis slider 106 is provided on the front surface of the column 104 so as to be reciprocable along a Y-axis guide rail (not shown) extending in the vertical direction or the Y-axis direction. A spindle head 108 is attached to the Y-axis slider 106, and supports a spindle 110 so as to be rotatable about a horizontal central axis O. A spindle servo motor (not shown) is provided on the spindle head 108 to rotate the spindle 110.

[0012] A pallet P, to which a workpiece fixture M such as a tombstone is attached, is removably fixed to the rotary table 114. In this embodiment, the workpiece fixture M has a workpiece mounting surface perpendicular to the Z axis when fixed to the rotary table 114 together with the pallet P, and a workpiece W is attached to this workpiece mounting surface. In this way, the workpiece W to be machined is mounted so as to face the tool T attached to the tip of the spindle 110. Note that the workpiece W may also be fixed directly to the pallet P without using a workpiece fixture M such as a tombstone.

[0013] Furthermore, in machine tool 100, an X-axis servomotor (not shown) serving as an X-axis feed device for driving column 104 in the X-axis direction, and a Z-axis servomotor (not shown) serving as a Z-axis feed device for driving Z-axis slider 112 in the Z-axis direction are disposed on bed 102. A Y-axis servomotor (not shown) serving as a Y-axis feed device for driving Y-axis slider 106 in the Y-axis direction is disposed on column 104. In this way, the X-axis feed device, Y-axis feed device, and Z-axis feed device linearly feed the main spindle 110 and rotary table 114 relatively in three orthogonal axis directions.

[0014] The machine tool according to this embodiment also includes a tool magazine 140 that stores a plurality of tools required for machining in the machine tool 100, an automatic tool changer 142 that replaces one of the tools stored in the tool magazine 140 with tool T attached to the tip of the spindle 110 of the machine tool 100, and a control device 150 that controls the machine tool 100.

[0015] Furthermore, the machine tool 100 according to this embodiment is equipped with a pallet exchange device 130 disposed on the upper surface of the bed 102, in front of the rotary table 114. The pallet exchange device 130 is equipped with a rotating shaft 134 that is rotatable about a vertical rotation axis OV, a rotating arm 132 that is attached to the upper end of the rotating shaft 134 and extends in the horizontal direction, a rotating door 122 that is attached to the upper end of the rotating shaft 134 and extends in a vertical plane, a rotating drive device that rotates the rotating shaft 134 about the rotation axis OV, and a rotating arm lifting device that raises and lowers the rotating arm 132.

[0016] In this embodiment, the swivel drive device includes a pallet exchanging servomotor 138 that is rotatable about a swivel axis OV, and a rotary encoder 138a that measures the rotational position (phase) of the pallet exchanging servomotor 138. The swivel arm lifting device also includes a lifting servomotor 144, a ball screw 146 directly connected to the output shaft of the lifting servomotor 144, and a ball screw nut 148 attached to the lower end of the swivel arm 132.

[0017] The main parts of machine tool 100, including Z-axis slider 112, rotary table 114, and spindle 110, as well as automatic tool changer 142 and pallet changer 130, are enclosed by splash guard 120. Furthermore, as shown in Figures 1 and 2, when pivot door 122 is in a rotational position perpendicular to the Z-axis of machine tool 100, the space within splash guard 120 is divided into a machining chamber 126 in which Z-axis slider 112, rotary table 114, spindle 110, and one end of a pivot arm 132 of pallet changer 130 (the end designated by reference number 132b in Figures 1 and 2) of machine tool 100 are disposed, and a workpiece setup chamber 128 in which the other end of pivot arm 132 (the end designated by reference number 132a in Figures 1 and 2) is disposed.

[0018] To allow the operator access to the work setup chamber 128, the splash guard 120 has a work setup chamber opening 120a and a work setup chamber safety door 124 that opens and closes the work setup chamber opening 120a. The work setup chamber safety door 124 has a window through which the operator can view the inside of the work setup chamber 128. The machine tool 100 is equipped with a work setup chamber-side operation panel 136 for operating the machine tool 100. The work setup chamber-side operation panel 136 is equipped with a display device, a keyboard (not shown) and / or buttons (not shown) for inputting numerical values ​​and commands to the control device 150, and a display device (not shown) for displaying the status of the machine tool 100 and confirming numerical values ​​input by the operator. The display device can be formed by a touch panel (not shown). The machining chamber 126 similarly has a machining chamber opening 120b, a machining chamber operator door 125 that opens and closes the machining chamber opening 120b, and a machining chamber-side operation panel 137 for operating the machine tool 100.

[0019] The control device 150 may be configured as a computer including a CPU (Central Processing Unit), memory devices such as RAM (Random Access Memory) and ROM (Read Only Memory), storage devices such as HDDs (Hard Disk Drives) and SSDs (Solid State Drives), input / output ports, a real-time clock (RTC), and a bidirectional bus interconnecting these components, and associated software. The control device 150 may be configured as software as part of a machine control device (not shown) that controls, among other things, the tool magazine 140, the automatic tool changer 142, and the pallet changer 130. The control device 150 may also include an NC device 156 (see FIG. 3) that controls the spindle servo motors, X-axis servo motors, Y-axis servo motors, Z-axis servo motors, and B-axis servo motors.

[0020] 3, there is shown a block diagram of a swing drive unit for the pallet exchange device 130 according to one embodiment. The swing drive unit according to this embodiment includes a rotary encoder 138a that detects the phase or rotation angle of the swing arm 132, the swing shaft 134, and the pallet exchange servo motor 138, a swing servo amplifier 152 that supplies a drive current to the pallet exchange servo motor 138 based on a control signal from a control device 150, an elevation servo amplifier 158 that supplies drive power to the elevation servo motor 144 based on a control signal from the control device 150, and an input device 154 that inputs parameters, which will be described later, to the control device 150.

[0021] The operation of this embodiment will be described below. When machining of the workpiece W is completed, pallet exchange is performed. Pallet exchange includes: 1) a first stage in which the pallet P on which the machined workpiece is attached is moved to the pallet exchange position; 2) a second stage in which the swivel arm 132 is raised and the pallet is placed on it; 3) a third stage in which the swivel arm 132 is rotated; and 4) a fourth stage in which the swivel arm 132 is lowered and the pallet is placed on the rotary table 114.

[0022] In the first stage, the pallet P on which the machined workpiece W is attached moves in the Z-axis direction toward the pallet exchange device 130 and stops at the pallet exchange standby position. At this time, the first end portion 132b of the swivel arm 132 of the pallet exchange device 130, which extends into the machining chamber 126, enters between the pallet P and the rotary table 114.

[0023] Next, the process moves to the second stage, in which the NC device 156 confirms that the rotary table 114 is positioned at the pallet exchange standby position, and then outputs a pallet exchange command to the control device 150. Upon receiving the pallet exchange command, the control device 150 outputs a control command to the lifting servo amplifier 158 in accordance with the pallet exchange program stored therein. The lifting servo amplifier 158 outputs a current to the lifting servo motor 144 based on the control command from the control device 150. This rotates the lifting servo motor 144 and the ball screw 146 directly connected to the output shaft of the lifting servo motor 144, and the ball screw nut 148 attached to the lower end of the swivel arm 132 moves upward.

[0024] This causes the swing arm 132 to rise together with the swing door 122. Furthermore, the pallet P is lifted from the rotary table 114 by the first end portion 132b of the swing arm 132, which extends into the machining chamber 126. Once the pallet P is placed on the swing arm, the rotary table 114 is moved along the Z axis in a direction away from the swing arm 132 by a command from the NC device 156 to a retracted position where it does not interfere with the swing arm 132. This completes the second stage of the pallet exchange.

[0025] Next, the process moves to the third stage, in which the swing servo amplifier 152 outputs a current to the pallet exchange servo motor 138 based on a control command from the control device 150. This causes the pallet exchange servo motor 138 to rotate about the swing axis OV, and the swing arm 132 and the swing door 122 swing 180° about the swing axis OV together with the swing shaft 134. When the swing arm 132 finishes swinging, the third stage ends.

[0026] Next, moving to the fourth stage, the NC device 156 moves the rotary table 114 along the Z axis from the retracted position to the pallet exchange standby position, and then rotates the lifting servo motor 144 so that the swivel arm 132 descends. As a result, the pallet that was placed on the second end portion 132a of the swivel arm 132 is placed on the rotary table 114, completing the fourth stage of pallet exchange. At this time, the machined workpiece W in the machining chamber 126 is placed inside the workpiece setup chamber 128, and the unmachined workpiece W that was prepared in the workpiece setup chamber 128 is placed in the machining chamber 126. In this way, the unmachined workpiece is exchanged for the machined workpiece.

[0027] During the pallet changing operation, coolant adhering to the components that rotate together with the rotating arm 132, such as the pallet P, workpiece fixture M, workpiece W, and rotating door 122, is scattered inside the work setup chamber 128 by centrifugal force and adheres to the window of the work setup chamber safety door 124, preventing the operator from observing the inside of the work setup chamber 128. To solve this problem, in this embodiment, the rotation command speed is changed during part of the rotation process of the rotating arm 132 and rotating door 122, i.e., during a certain section during the third stage of the pallet changing operation.

[0028] 4, there is shown a graph illustrating the change in speed of the swing operation of the swing arm 132 during a pallet exchange process. In the graph of FIG. 4, the vertical axis represents the commanded swing speed (rpm) of the swing arm 132. The horizontal axis represents the time (seconds) during one pallet exchange process, with T=0 representing the start of the pallet exchange process. The swing arm accelerates from a speed of 0 at T=0 to the commanded swing speed, maintains the commanded swing speed throughout substantially the entire pallet exchange, and decelerates from the commanded swing speed to a speed of 0 as the swing end position approaches.

[0029] In Figure 4, line L1 shows the change in swing speed during a normal pallet exchange operation in which the swing arm 132 and the swing door 122 swing at a swing command speed V1 (hereinafter referred to as the "high swing command speed") substantially throughout the entire pallet exchange process. Generally, as described above, a shorter pallet exchange time is preferable, so the high swing command speed V1 is set based on a speed at which the pallet carrying the workpieces will not tip over due to centrifugal force during the swing, or based on the upper limit output of the swing mechanism. Line L2 shows the change in swing speed during a conventional pallet exchange operation in which the swing arm 132 and the swing door 122 swing at a swing command speed V2 (hereinafter referred to as the "low swing command speed") lower than V1 to prevent or reduce coolant splashing. In the prior art, the swing speed is reduced from the high swing command speed V1 to the low swing command speed V2 substantially throughout the entire pallet exchange process. This reduces the amount of coolant that is scattered due to centrifugal force during the pallet exchange operation and prevents or reduces the amount of coolant adhering to the window of the work setup room safety door 124, but it increases the time required for the pallet exchange process from T3 to T5, resulting in a decrease in productivity.

[0030] Line L3 shows the change in swing speed during pallet exchange operation according to this embodiment. In this embodiment, after the pallet exchange operation starts, at time T1, the swing speed is reduced from high swing command speed V1 to low swing command speed V2, and at time T2, the swing speed is returned from low swing command speed V2 to high swing command speed V1. Of course, if the position of the swing arm at time T2 is close to the swing end position and it is not possible to return from low swing command speed V2 to high swing command speed V1 in time, it is possible to leave the swing arm at the low swing command speed V2 without returning.

[0031] In this way, in order to reduce the swing speed of the swing arm 132 during a certain section of the pallet changing operation, the timing for reducing the swing speed from the high swing command speed V1 to the low swing command speed V2 and then returning from the low swing command speed V2 to the high swing command speed V1, the degree to which the swing speed is reduced, or the high swing command speed V1 and the low swing command speed V2, are input to the control device 150 from the input device 154. As will be described below, in this embodiment, the input device 154 is formed by a touch panel that is a display device of the work setup room side operation panel 136.

[0032] 5 shows an example of a graphical user interface displayed on a touch panel. The touch panel as input device 154 receives input of parameters for the pallet exchange device 130, such as a low swing command speed V2, and a speed change start point P1 and a speed change end point P2 for switching the swing speed of the swing arm 132 between the high swing command speed V1 and the low swing command speed V2.

[0033] 5, reference numeral 200 indicates a graphical user interface screen displayed on the touch panel of the work setup room side operation panel 136 serving as a display device. The graphical user interface screen 200 includes a graphic display 202 for the pallet exchange device 130 and a parameter display area 210. The graphic display 202 for the pallet exchange device 130 includes the rotating arm 132, the pallet P, the rotating door 204, a window 206 of the work setup room safety door 124, and trajectories 208 drawn by the tips of the rotating arm 132, the pallet P, and the rotating door 204 during rotation.

[0034] The parameter display area 210 includes an area 212 displaying the phase θ1 of a speed change start point P1 at which the swing speed is changed to a low swing command speed V2, an area 214 displaying the phase θ2 of a speed change end point P2 at which the swing speed is returned to the high swing command speed V1, and an area 216 displaying the low swing command speed V2. By tapping a point on the trajectory 208 on the graphical user interface screen 200, the operator can automatically input the phases θ1 and θ2 from the standby position at which the swing door 204 is perpendicular to the Z axis, and set the speed change start point P1 and the speed change end point P2 in the control device 150.

[0035] Thus, in this embodiment, the timing for reducing the swing speed from the high swing command speed V1 to the low swing command speed V2 and for returning from the low swing command speed V2 to the high swing command speed V1 is set in the control device 150 by inputting the speed change start point P1 and the speed change end point P2 via the graphical user interface screen 200. In other words, the graphical user interface screen 200 constitutes a phase setting device that sets the phases of the speed change start point P1 and the speed change end point P2 for switching the swing speed of the swing arm 132 between the high swing command speed V1 and the low swing command speed V2.

[0036] The swivel arm 132 alternates between counterclockwise rotation shown in FIG. 5 and clockwise rotation, which is the opposite direction to that shown in FIG. 5, every time a pallet is changed. During clockwise rotation, the swivel speed is controlled by replacing P2 with P1 and P1 with P2. Furthermore, the phases θ1 and θ2 do not have to be angles from a standby position perpendicular to the Z axis, but may be angles from a direction horizontal to the Z axis, for example. In short, it is sufficient if the speed change start point P1 and speed change end point P2 can be uniquely determined during a pallet change.

[0037] In the embodiment of FIG. 5 , the low swing command speed V2 is not directly input as a reduced swing command speed, but is instead input as a deceleration rate δ% relative to the high swing command speed V1. The deceleration rate δ% can be input using the keys on the work setup room-side operation panel 136, for example, by the operator tapping area 216, which activates the area 216. Alternatively, when the operator taps area 216, a dialog box (not shown) for inputting the deceleration rate δ% may be displayed on the graphical user interface screen 200. The reduced low swing command speed V2 may also be input directly. Of course, the high swing command speed V1, the low swing command speed V2, and the deceleration rate δ% may be input as G-code, M-code, machine parameters, or NC parameters without using a graphical user interface. Similar operations can also be performed using the machining room-side operation panel 137.

[0038] In this embodiment, when a pallet changing operation is started, the control device 150 monitors the signal from the rotary encoder 138a, and when the phase or rotation angle of the pallet changing servo motor 138, i.e., the phase or rotation angle of the swing arm 132 relative to the swing axis OV, becomes θ1, it outputs a control command to the swing servo amplifier 152 to reduce the output current value to a current value corresponding to the low swing command speed V2. Based on the control command from the control device 150, the swing servo amplifier 152 outputs a current corresponding to the low swing command speed V2 to the pallet changing servo motor 138. As a result, the swing speed of the pallet changing servo motor 138 is reduced from the high swing command speed V1 to the low swing command speed V2.

[0039] The control device 150 continues to monitor the signal from the rotary encoder 138a, and when the phase or rotation angle of the swing arm 132 becomes θ2, outputs a control command to the swing servo amplifier 152 to return the output current value to a current value corresponding to the high swing command speed V1. Based on the control command from the control device 150, the swing servo amplifier 152 outputs a current corresponding to the high swing command speed V1 to the pallet exchanging servo motor 138. As a result, the swing speed of the pallet exchanging servo motor 138 returns from the low swing command speed V2 to the high swing command speed V1.

[0040] According to this embodiment, by reducing the swing speed during a certain section of the pallet changing operation, it is possible to prevent or reduce the amount of coolant scattered by centrifugal force during the pallet changing operation from adhering to the window of the work setup room safety door 124, without excessively increasing the time required for the pallet changing. According to this embodiment, the time required for the pallet changing process is reduced to T4 from T5 in the prior art in which the swing speed is reduced from the high swing command speed V1 to the low swing command speed V2 throughout substantially the entire pallet changing process.

[0041] In the embodiment described above, the work setup room safety door 124 is provided with a window for visually observing the inside of the work setup room 128, but even if a side window (not shown) is provided on the side of the splash guard 120 or an on-board camera (not shown) is provided inside the work setup room 128, it can also prevent coolant from splashing onto the side window or on-board camera.

[0042] At this time, a low swing command speed V3 different from the low swing command speed V2, and additional speed change start points P3 and P4 may be set depending on the distance from the side windows or the rotating door for the onboard camera, and the swing speed may be changed in three stages: high swing command speed V1, low swing command speed V2, and low swing command speed V3. In short, the intention of the present invention is to change the speed during pallet exchange at any point in order to prevent coolant from splashing without reducing productivity as much as possible, and for this purpose the number of changes and the change speed can be set freely.

[0043] According to this embodiment, the operator can easily change the parameters at any time while observing the coolant scattering during the pallet exchange operation. For example, if the workpiece W is tall or has a spoon-shaped recess where coolant can easily accumulate, the coolant is likely to scatter far away, but it is difficult to predict the area where the coolant will scatter in advance. Therefore, there is an advantage in that the operator can change the parameters, particularly the low swing command speed V2, while observing the coolant scattering during the pallet exchange operation.

[0044] Although a preferred embodiment of the present invention has been described, it will be obvious to those skilled in the art that the present invention is not limited to the above-described embodiment and that various modifications and improvements are possible. In the example of Fig. 3, the rotary encoder 138a is used to detect the phase or rotation angle of the swing arm 132, so that the swing speed is reduced from the high swing command speed V1 to the low swing command speed V2 when the speed change start point P1 and the speed change end point P2 are reached, and then returned from the low swing command speed V2 to the high swing command speed V1. However, a time counter may be provided to measure the time from the start of the pallet exchange operation to change the swing speed.

[0045] In this case, based on the speed change start point P1, speed change end point P2, high swing command speed V1, and low swing command speed V2 input on the graphical user interface screen 200, the control device 150 can calculate in advance the time from the start of the pallet exchange until the swing arm 132 reaches the speed change start point P1 and the speed change end point P2, or measure the time simultaneously with the start of the pallet exchange using a time counter, and have the control device 150 calculate the phase or rotation angle of the swing arm, thereby making it possible to reduce the swing speed from the high swing command speed V1 to the low swing command speed V2 at an appropriate timing, and then return from the low swing command speed V2 to the high swing command speed V1.

[0046] In the above-described embodiment, the swing drive device includes the pallet exchange servo motor 138, which is an electric motor, but the present invention is not limited to this. The swing drive device may include, for example, a hydraulic motor such as a hydraulic cylinder.

[0047] In the modified example shown in FIG. 6 , the swing drive device includes a hydraulic cylinder 160 instead of the above-described pallet exchange servo motor 138. The hydraulic cylinder 160 swings the swing shaft 134, the swing arm 132, and the swing door 122 via a rack-and-pinion mechanism 162. A piston (not shown) of the hydraulic cylinder 160 is coupled to a rack gear (not shown) of the rack-and-pinion mechanism 162, and a pinion (not shown) that engages with the rack gear is coaxially coupled to the swing shaft 134. The swing drive device further includes a hydraulic pressure supply device 170 that supplies hydraulic pressure to the hydraulic cylinder 160 and a time counter 164. If the control device 150 is equipped with an RTC, the time counter 164 may be an RTC.

[0048] 7 , a hydraulic supply device 170 shown as an example includes a hydraulic pump 172 that draws hydraulic oil from a hydraulic oil tank 174, pressurizes it to a predetermined pressure, and supplies it to the hydraulic cylinder 160. The hydraulic supply device 170 also includes a proportional electromagnetic control valve 176 that is disposed between the hydraulic pump 172 and the hydraulic cylinder 160 and can change the flow rate of hydraulic oil to be output in response to an electric signal. The proportional electromagnetic control valve 176 can also include, for example, a two-position or three-position directional change valve. The hydraulic cylinder 160 extends or retracts depending on the position of the directional change valve of the proportional electromagnetic control valve 176.

[0049] When the control device 150 receives a pallet exchange command from the NC device 156, it outputs a hydraulic pressure supply command to the hydraulic pressure supply device 170 in accordance with the pallet exchange program stored therein. The hydraulic pressure supply command is a command signal voltage supplied to a proportional electromagnetic control valve 176. In this embodiment, the hydraulic pressure supply device 170 is equipped with a proportional electromagnetic control valve 176 that can change the flow rate according to the command signal voltage issued from the control device 150, and is therefore able to change the amount of hydraulic oil supplied per unit time to the hydraulic cylinder 160. When the proportional electromagnetic control valve 176 closes, the hydraulic oil is collected in a hydraulic oil tank 174 without being supplied to the hydraulic cylinder 160.

[0050] In the example of FIG. 3, the rotary encoder 138a is used to detect the phase or rotation angle of the swing arm 132, and when the speed change start point P1 and the speed change end point P2 are reached, the swing speed is reduced from the high swing command speed V1 to the low swing command speed V2, and then returned from the low swing speed V2 to the high swing command speed V1. However, in the modified example of FIG. 6, the swing command speed is changed by measuring the time from the start of the pallet exchange operation using a time counter 164.

[0051] In other words, as described above, based on the speed change start point P1, speed change end point P2, high swing command speed V1, and low swing command speed V2 input on the graphical user interface screen 200, the control device 150 can calculate the time from the start of the pallet exchange until the phase or rotation angle of the swing arm 132 reaches the speed change start point P1 and the speed change end point P2. Alternatively, the time counter 164 can measure the time simultaneously with the start of the pallet exchange, and the control device 150 can reduce the swing speed from the high swing command speed V1 to the low swing command speed V2 at an appropriate timing to calculate the phase or rotation angle of the swing arm, and then return the swing speed from the low swing command speed V2 to the high swing command speed V1.

[0052] In the modified example of FIG. 6, instead of the time counter 164, a limit switch (not shown) installed on the rack and pinion mechanism or the rotating arm may be used to detect that the phase or rotation angle of the rotating arm 132 has reached the shift start point P1 and the shift end point P2.

[0053] In the embodiment described above, the splash guard 120 has a work setup chamber opening 120a through which the operator can access the work setup chamber 128, and a work setup chamber safety door 124 is provided at the work setup chamber opening 120a so that it can be opened and closed. However, the present invention is not limited to this, and may also be applied to machine tools used in so-called automated machining systems equipped with a pallet conveying line in which the operator does not have access to the work setup chamber.

[0054] Referring to Figure 8, another example of a machine tool to which the present invention is applied is shown. In Figure 8, machine tool 300, unlike machine tool 100, is configured such that, in principle, an operator does not have access to the setup room. Like machine tool 100, machine tool 300 is equipped with a spindle head 304 that supports a spindle 302 rotatably about a horizontal central axis O, a table 306 that is provided so as to be movable in the Z-axis direction, a pallet changer including a rotating arm 308 and a rotating door 310 that are provided so as to be rotatable together with a rotating shaft 312 extending vertically, a splash guard 316 that surrounds the spindle 302, spindle head 304, table 306, and pallet changers 308, 310, and 312, and a control device 350 that controls machine tool 300.

[0055] In the machine tool 300, the rotating arm 308, the rotating door 310, and the rotating shaft 312 are provided with the rotating drive device (not shown) in the previously described embodiment. Furthermore, as in the previously described embodiment, the machine tool 300 is provided with a phase detection device such as a rotary encoder, limit switch, or time counter that detects the phase or rotation angle of the pallet exchange device, i.e., the phase or rotation angle of the rotating arm 308.

[0056] The spindle 302, spindle head 304, table 306, pallet changers 308, 310, 312, spindle 302, spindle head 304, table 306, splash guard 316, and control device 350 are configured in the same manner as in the previously described embodiment. Although not shown in Figure 8, machine tool 300 also has a tool magazine and a tool changer.

[0057] Machine tool 300 is equipped with a pallet transport device 320. Pallet transport device 320 includes a transport vehicle 322 that is reciprocally movable along rails 326 extending in the X-axis direction, and a pallet delivery arm 324 that is mounted on transport vehicle 322 and can move back and forth in the Z-axis direction. Pallet delivery arm 324 is able to access swivel arm 308 of the pallet exchange device within workpiece setup chamber 328 through opening 316a in splash guard 316. As described above, this configuration can also be used to create an automated machining system in which multiple machine tools (not limited to machining centers), pallet stockers for storing machined or unmachined pallets, and workpiece washing devices are arranged along rail 326, and pallets are transported and delivered between them by transport vehicle 322.

[0058] In this example, the splash guard 316 does not have a work setup room safety door that opens and closes the opening 316a. In this case, in the existing configuration, coolant splashing from the opening 312a contaminates the floor of the pallet transport device 320. If the coolant used in the cutting process is water-soluble, it can spoil and cause a bad odor, worsening the factory environment. If the coolant is water-insoluble, it can also cause a fire. Manually cleaning this contamination requires stopping the transport vehicle 322 for safety reasons, which reduces productivity. The present invention can also be applied to such cases, preventing coolant from splashing outside the splash guard 316 from the opening 316a without excessively increasing the time required for pallet replacement. Furthermore, in this case, command speeds and speed change points can be set using the machining chamber side operation panel 318.

[0059] In the above-described embodiment, machine tools 100, 300 constitute horizontal machining centers, but the present invention is not limited to this and may also be applied to vertical machining centers. Furthermore, the present invention is not limited to machine tools and may be applied to, for example, a pallet exchange device of a cleaning device that is installed alongside machine tool 300 in an automated machining system, which transfers pallets carrying machined workpieces to and from pallet transport device 320, and automatically cleans the machined workpieces.

[0060] 100 Machine tool 112 Z-axis slider 114 Rotary table 120 Splash guard 120a Work setup room opening 120b Machining room opening 122 Swivel door 124 Work setup room safety door 125 Machining room operator door 126 Machining room 128 Work setup room 130 Pallet exchange device 132 Swivel arm 134 Swivel axis 136 Work setup room side operation panel 137 Machining room side operation panel 138 Pallet exchange servo motor 138a Rotary encoder 144 Elevation servo motor 150 Control device 152 Swivel servo amplifier 154 Input device 156 NC device 158 Elevation servo amplifier 160 Hydraulic cylinder 162 Rack and pinion mechanism

Claims

1. In a pallet changer for a machine tool that exchanges pallets using a swivel arm, a swivel drive device capable of switching the swivel command speed to different values during the swiveling of the swivel arm, a phase setting device for setting a phase for switching the swivel command speed of the swivel arm, and a control device for switching the swivel command speed of the swivel drive device according to the phase set by the phase setting device. A pallet changer characterized by comprising the above.

2. The pallet changer according to claim 1, wherein the phase setting device is a graphical user interface displayed on a display device.

3. The pallet changer according to claim 1, wherein the phase for switching the swivel command speed includes a speed change start point for switching the swivel speed of the swivel arm from a high swivel command speed to a low swivel command speed and a speed change end point for switching the swivel speed of the swivel arm from the low swivel command speed to the high swivel command speed.

4. The pallet changer according to claim 2, wherein the graphical user interface includes a movement locus of the swivel arm, and an operator can indicate the speed change start point and the speed change end point on the movement locus.

5. The pallet changer according to claim 1, wherein the swivel drive device includes a servo motor for swiveling the swivel arm around a vertical axis and a rotary encoder for detecting the rotation angle of the servo motor.

6. The pallet changer according to claim 1, wherein the swivel drive device has a servo motor for swiveling the swivel arm around a vertical axis, the phase setting device has a time counter for measuring the elapsed time since the start of pallet exchange, and the phase for switching the commanded swivel speed of the swivel arm is set by the time measured by the time counter.

Images