Machine tool with workpiece conveyor

Abstract

To provide a machine tool with a workpiece conveyor, that performs drive control of a workpiece conveyor based on a workpiece weight measured by a weight measuring device.SOLUTION: A machine tool with a workpiece conveyor includes: a plurality of processing devices that execute processing of a workpiece in a processing chamber; a workpiece conveyor for carrying-in and carrying-out a workpiece to / from the processing chamber; a workpiece weight measuring device disposed on a conveyance route of carrying-in a workpiece to the processing chamber using the workpiece conveyor; and a control device for drive-controlling the processing devices and the workpiece conveyor. In the workpiece conveyor, drive control is performed by the control device according to preset conveyance conditions, based on a value of the workpiece weight measured by the workpiece weight measuring device when carrying-in the workpiece.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a machine tool that loads and unloads workpieces by a mounted workpiece conveyor, and in which drive control of the workpiece conveyor is performed based on the workpiece weight at the time of loading measured by a weight measuring device.

Background Art

[0002] A workpiece conveyor is integrally provided in a machine tool for automatically machining workpieces, and the workpiece is loaded into and unloaded from the machining chamber by its conveyance control. The following Patent Document 1 discloses a conventional example of a machine tool with a workpiece conveyor capable of adjusting the conveyance speed according to the workpiece weight. In this machine tool, a robot hand having a chuck mechanism for gripping a workpiece is connected to a drive unit composed of a servo motor by a drive transmission means of an endless belt. Further, the robot hand and the drive transmission means are attached along a traveling rail arranged in the left-right direction of the machine tool.

[0003] In this conventional example, a weight detection means is provided in the control unit, and the weight is automatically detected from the load value of the servo motor when gripping the workpiece and starting to move. Three weight classifications, large, medium, and small, are set, and in the control unit, conveyance speeds such as an optimal fast feed speed and optimal acceleration / deceleration time constants for each classification are set as conveyance conditions. Therefore, in such a conventional example, if the workpiece to be conveyed is a heavier object, the workpiece is conveyed at a slow speed with less shaking, and if the workpiece is a lighter object, the workpiece is conveyed at a relatively high speed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional machine tool with a work conveyor, since the work weight is detected from the load value of the servo motor to determine the work conveyor speed, the control program has become complicated. Also, it has been difficult to measure a minute weight difference, and it has not been possible to cope with determining whether the work is the work to be machined or not.

[0006] Therefore, an object of the present invention is to provide a machine tool with a work conveyor that performs drive control of the work conveyor based on the work weight measured by a weight measuring device in order to solve such problems.

Means for Solving the Problems

[0007] The machine tool with a work conveyor according to the present invention includes a plurality of processing devices that execute processing of a work in a processing chamber, a work conveyor that carries the work into and out of the processing chamber, a work weight measuring device disposed on a conveyance route for carrying the work into the processing chamber by the work conveyor, and a control device that drives and controls the processing device and the work conveyor. The work conveyor is driven and controlled by the control device according to preset conveyance conditions based on the value of the work weight measured by the work weight measuring device when the work is carried in.

Effects of the Invention

[0008] According to the above configuration, processing of the work is executed by drive control by a plurality of processing devices in the processing chamber, and the work is carried into and out of the processing chamber by the work conveyor. However, the work weight is measured by the weight measuring device disposed on the conveyance route for carrying the work into the processing chamber. As a result, the work conveyor is driven and controlled by the control device according to the preset conveyance conditions based on the measured value.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiment for Carrying Out the Invention

[0010] An embodiment of a machine tool with a workpiece transporter according to the present invention will be described below with reference to the drawings. FIG. 1 is a front view simply showing the machine tool with a workpiece transporter of this embodiment. This machine tool with a workpiece transporter (hereinafter simply referred to as "machine tool") 1 is supported by leveling blocks arranged at four locations on the front, rear, left, and right of the bed 2, and is configured to be leveled by adjusting the height of each. The machine tool 1 has various processing devices such as a workpiece spindle device 5 and a turret device 6 mounted on the bed 2 covered by a machine body cover (not shown), and a closed processing chamber where coolant is sprayed during processing is formed. Further, the machine tool 1 is provided with a gantry-type workpiece transporter 7 for transporting a workpiece to be processed between the outside of the machine and the processing chamber.

[0011] The workpiece spindle device 5 of the machine tool 1, which is a single-axis lathe, is configured such that the central direction of its spindle is in the machine width direction which is the longitudinal direction of the bed 2. Therefore, in this embodiment, the machine width direction parallel to the spindle is defined as the Z-axis, and the vertical direction perpendicular to the Z-axis is defined as the X-axis for explanation. A spindle chuck 11 for gripping a workpiece is rotatably provided on the workpiece spindle device 5, and rotation is imparted to the workpiece gripped by the spindle chuck 11 by driving a spindle motor. The turret device 6 has a plurality of tools attached to a tool rest 12, and a specific tool can be selected by indexing according to the machining content.

[0012] The turret device 6 is provided with a guide rail 13 in the Z-axis direction so that the tool rest 12 can move in a direction parallel to the spindle. During machining, the tool indexed by turning can be linearly moved in the Z-axis direction. That is, the device body 14 is slidably assembled with respect to the guide rail 13, and the device body 14 is configured with a drive mechanism that converts the rotation of the Z-axis servo motor into linear motion by a ball screw, enabling a predetermined movement along the guide rail 13. Further, the tool rest 12 is assembled to the device body 14 via a linear guide and is also configured to be movable in the X-axis direction by a ball screw that converts the rotation of the X-axis servo motor into linear motion.

[0013] On the left and right outer sides of the body of the machine tool 1, work stockers 51 and 53 are arranged, and the work transfer machine 7 automatically transfers the work between the machining chamber. In the case of this embodiment, a plurality of unprocessed workpieces are loaded on the work stocker 51 located on the left side of the drawing, and the processed workpieces processed by the machine tool 1 are collected to the work stocker 53 on the right side of the drawing. The work transfer machine 7 has columns 21 fixed and erected at both ends in the width direction of the bed 2, and a gantry beam 22 having a length exceeding the width dimension of the bed 2 is fixed in a horizontal state parallel to the Z-axis at the top thereof. Then, a lifting arm 24 is assembled to the traveling base 23 so as to be suspended with respect to the gantry beam 22, and the traveling base 23 is configured to be movable in the Z-axis direction.

[0014] The work transfer machine 7 has a guide rail parallel to the Z-axis fixed to the gantry beam 22, and the traveling base 23 is slidably assembled thereto. In addition to the guide rail, a rack parallel to the Z-axis is fixed to the gantry beam 22, and a pinion fixed to the rotation shaft of the traveling servo motor provided on the traveling base 23 meshes therewith. Therefore, by controlling the rotation of the traveling servo motor, the traveling base 23 moves in the Z-axis direction, and arbitrary positioning can be performed in the width direction of the machine body. Further, the traveling base 23 has a vertical lifting arm 24 assembled to be slidable in the X-axis direction with respect to the traveling base 23.

[0015] The lifting arm 24 has a rack fixed in its longitudinal direction (X-axis direction), and meshes with a pinion fixed to the rotating shaft of a lifting servo motor provided on the traveling base 23. Therefore, by controlling the rotation of the lifting servo motor, the lifting arm 24 is moved up and down and positioned at a predetermined height. A robot hand 25 is attached to the lower end of such a lifting arm 24, and the work transfer machine 7 positions the robot hand 25 inside or outside the machine by moving the traveling base 23 and the lifting arm 24. The robot hand 25 includes a pair of chuck mechanisms 31, 33, and can grip and release the work in each of them.

[0016] There are various workpieces to be processed by the machine tool 1, and since their weights are different, the work transfer machine 7 sets the transfer conditions according to the workpiece weight. That is, since the inertial force acting due to the workpiece weight becomes a load on the work transfer machine 7, the transfer speed and acceleration decrease when the workpiece weight is large, and the transfer speed and acceleration are increased when the workpiece weight is small. Therefore, when the work is transferred by the work transfer machine 7, the workpiece weight must be grasped. Therefore, a workpiece weight measuring device 55 for measuring the workpiece weight is connected to the machine tool 1.

[0017] In the present embodiment, the workpiece weight measuring device 55 is provided in the workpiece stocker 51 on the workpiece loading side. The workpiece stockers 51, 53 are provided with a drive mechanism that can send out or collect a predetermined workpiece according to the processing content. The drive mechanism has an endless chain spanned in an oval shape by a pair of sprockets, and a plurality of transfer tables are connected in a row in the circumferential direction. Further, as the drive mechanism, a lift is provided at the workpiece handover position with the work transfer machine 7 so that the workpiece mounted on the transfer table can be lifted. The workpiece weight measuring device 55 is incorporated as a part of such a workpiece stocker 51 and is provided in the middle of the transfer route where the work transfer machine 7 transfers the workpiece to the machine tool 1.

[0018] The work stockers 51 and 53 are peripheral devices that are automatically controlled for the drive mechanisms but do not have their own control devices. Therefore, the work stockers 51 and 53 are connected to the control device of the machine tool 1, which is the upper-level machine, by cables, and automatic control is executed for each drive mechanism according to the drive control program input thereto. Also, regarding the work weight measuring device 55 provided in the work stocker 51, a cable is connected such that the weight sensor 58 transmits the weight measurement value to the control device of the machine tool 1.

[0019] Figure 2 is a block diagram showing a control system for controlling the machine tool 1. A microprocessor (CPU) 41, a ROM 42, a RAM 43, and a nonvolatile memory 44 are connected to the control device 4 of the machine tool 1 via bus lines. The CPU 41 comprehensively controls the entire control device. The system programs and control parameters executed by the CPU 41 are stored in the ROM 42, and temporary arithmetic data, display data, etc. are stored in the RAM 43. Also, information necessary for the processes performed by the CPU 41 is stored in the nonvolatile memory 44, and the machining control program of the machine tool 1, etc. are stored therein.

[0020] The control device 4 is provided with an I / O port 45, and drive motors of the work spindle device 5, the turret device 6, and the work conveyor 7 are connected via drivers to the I / O port 45. As described above, the work stockers 51 and 53 are connected to this control device 4 via drivers, and the respective drive control programs are input and stored in the nonvolatile memory 44. Also, an operation display device 8 is connected to the I / O port 45. The operation display device 8 is provided with various operation buttons and switches, as well as a touch panel type monitor. Various information such as the display of the operation screen and the operation status is displayed on the monitor. Also, the operation display device 8 functions as an input interface for operating each device, an input interface for taking in various drive control programs and operation parameters, etc.

[0021] Incidentally, in the machine tool 1, the weight of the workpiece is measured by the weight sensor 58 during the conveyance from the workpiece stocker 51 to the machining chamber. Then, when the measured value is transmitted to the control device 4, the workpiece transporter 7 is driven and controlled according to the corresponding conveyance conditions. As shown in FIG. 3, parameters set in the control device 4 are input and stored as conveyance conditions. In particular, since the robot hand 25 of the workpiece transporter 7 of the present embodiment is provided with a pair of chuck mechanisms 31 and 33, the distinction between the double gripping state in which the workpiece is held by both hands and the single gripping state in which the workpiece is held by only one hand is added to the conveyance conditions. Note that since FIG. 3 shows the conveyance conditions in a simplified manner, the parameters may be set by further subdividing the conditions or the like.

[0022] The conveyance conditions shown in FIG. 3 are classified according to the double gripping state, single gripping state, or non-gripping state of the workpiece in the robot hand 25 and the distinction of the workpiece weight based on a predetermined threshold value. This is because the workpiece transporter 7 can have the robot hand 25 grip a maximum of two workpieces, and the total weight changes depending on the number of workpieces conveyed at one time and the weight of the workpieces themselves. The chuck mechanisms 31 and 33 are provided with gripping sensors 59 so that the number of workpieces gripped by the robot hand 25 can be confirmed. Therefore, for the conveyance conditions for driving and controlling the workpiece transporter 7, parameters are set respectively regarding the conveyance speed according to the number of workpieces and the weight of the workpieces themselves, and the acceleration time constant and deceleration time constant at the start and stop of conveyance.

[0023] Specifically, when the robot hand 25 is in the double gripping state and the workpiece weight is equal to or greater than the threshold value, it is parameter A. Similarly, when the robot hand 25 is in the double gripping state and the workpiece weight is less than the threshold value, it is parameter B. When the robot hand 25 is in the single gripping state and the workpiece weight is equal to or greater than the threshold value, it is parameter C. Similarly, when the robot hand 25 is in the single gripping state and the workpiece weight is less than the threshold value, it is parameter D. When the robot hand 25 moves without gripping the workpiece, it is parameter E.

[0024] Subsequently, in the workpiece machining of the machine tool 1, the workpiece gripped by the robot hand 25 that has moved to the workpiece stocker 51 by the drive of the workpiece conveyor 7 is taken out. The workpiece is carried into the machining chamber and conveyed to the workpiece spindle device 5, and the workpiece is transferred between the spindle chuck 11. In the turret device 6, the tool on the tool rest 12 is rotated and indexed, the device body 14 is moved along the guide rail 13 by the drive mechanism, and the tool is applied to the workpiece rotating in the workpiece spindle device 5 to perform predetermined machining such as outer diameter turning. The workpiece that has undergone the machining process is again gripped by the robot hand 25 of the workpiece conveyor 7, carried out of the machining chamber, and conveyed to the workpiece stocker 53 on the recovery side.

[0025] By the way, in the workpiece conveyor 7, the following workpiece conveyance using a pair of chuck mechanisms 31 and 33 is performed. For example, the workpiece is taken out from the workpiece stocker 51 by the chuck mechanism 31. At this time, the robot hand 25 is gripping one workpiece. Then, after the workpiece is carried to the machining chamber, the empty chuck mechanism 33 receives the workpiece after the machining process gripped by the spindle chuck 11. On the other hand, the workpiece before machining gripped by the chuck mechanism 31 is transferred to the spindle chuck 11, and machining is performed on the workpiece gripped by the spindle chuck 11 as described above.

[0026] Before the workpiece of the spindle chuck 11 is machined, the workpiece gripped by the chuck mechanism 33 is carried out of the machining chamber and conveyed to the workpiece stocker 53. At this time as well, the robot hand 25 is gripping one workpiece. Thereafter, the robot hand 25 moves to the workpiece stocker 51 in a state without a workpiece, and a new workpiece is taken out by the chuck mechanism 31, and the same workpiece conveyance process is repeated. The conveyance conditions in such a case are determined based on one workpiece, no workpiece, and the workpiece weight.

[0027] The workpiece machining of the machine tool 1 is performed such that the same number of workpieces set for each lot are carried out from the workpiece stocker 51 and predetermined machining is performed. At that time, the workpiece transporter 7 will repeat the conveyance process of the same pattern. In the present embodiment, the workpiece weight is determined at the timing of tool change, and data for the conveyance process for the workpiece transporter 7 is obtained. After the tool change, the workpiece transporter 7 receives a predetermined workpiece from the workpiece stocker 51 by the robot hand 25, and the workpiece is transferred to the weight sensor 58 of the workpiece weight measuring device 55. Then, the value of the workpiece weight measured by the weight sensor 58 is transmitted to the control device 4.

[0028] In the control device 4, the weight of the workpiece is determined by comparing the workpiece weight with a preset threshold value. If the workpiece is a heavy workpiece with a weight equal to or greater than the threshold value, parameters A, C, and E are selected as the conveyance pattern for the corresponding workpiece. On the other hand, if it is determined that the workpiece is a light workpiece with a weight less than the threshold value, parameters B, D, and E are selected as the conveyance pattern for the corresponding workpiece. Therefore, in the example of workpiece conveyance described above, it is determined whether the robot hand 25 is gripping one workpiece or not gripping a workpiece by the gripping sensor 59, and conveyance control is performed according to the selected parameters accordingly.

[0029] Therefore, according to the present embodiment, it is possible to easily measure the workpiece weight by the weight sensor 58, and the conveyance speed, acceleration time constant, and deceleration time constant of the robot hand 25 holding the workpiece can be controlled with appropriate values according to the measured value. Since the workpiece weight measuring device 55 is located on the conveyance route of the workpiece, the time required for measuring the workpiece weight can also be short. In addition, as long as the position of the workpiece weight measuring device 55 is on the conveyance route, the weight sensor 58 can be arbitrarily set without particular limitation, so it can be retrofitted to an existing machine tool and is also easy to improve.

[0030] Also, in this embodiment, the work weighing device 55 can accurately measure the weight of the work. For example, if there are five types of work a - e as shown in FIG. 4 for the work to be processed, and the work to be processed on a certain day is work a, c, and d, then those works will be loaded into the work stocker 51 according to the number of processed pieces. However, the loading work performed by the operator may result in mistakes in the work or misidentifying the carrier of the work stocker 51 to be loaded.

[0031] Therefore, in the machine tool 1, the work weight data shown in FIG. 4 is pre - input and stored in the control device 4, and it is configured to determine whether the work being processed is the target work based on the measured value of the weight sensor 58. That is, when the work is carried from the work stocker 51 into the processing chamber, the work being transported is placed on the weight sensor 58, and the measured value of the work weight is transmitted to the control device 4. Therefore, the type of work is determined based on the work weight data, and it is determined whether it is the target work in the processing program.

[0032] If the measured value of the work weight is within a predetermined error range with respect to the weight of the work weight data of the target work (for example, "work a"), the work is determined to be correct. On the other hand, if it exceeds the predetermined error, the work is determined to be incorrect, and the result is displayed on the operation display device 7, etc., and a warning process is performed for the operator. Note that if measurements are taken for all the work carried out from the work stocker 51, a large amount of time will be lost. Therefore, measurements are taken for each carrier on which a plurality of works are stacked. Or, similar to the determination of the above - mentioned parameters, measurements may be taken for each lot.

[0033] As described above, one embodiment of the present invention has been explained, but the present invention is not limited to this, and various changes can be made without departing from the gist thereof. For example, in the above embodiment, the workpiece weight measuring device 55 is arranged on the workpiece stocker 51. However, since it is not particularly limited as long as it is on the conveyance route for carrying the workpiece into the machining chamber, the machine tool 1 may be provided with the workpiece weight measuring device 55. Also, in the above embodiment, only the case where the robot hand 25 conveys one workpiece is shown. However, the conveyance of the workpiece varies depending on the machine tool and the conveyance pattern, and the present invention can be applied to each of them.

Explanation of Reference Numerals

[0034] 1... Machine tool 4... Control device 5... Work spindle device 6... Turret device 7... Work conveyor 8... Operation display device 11... Spindle chuck 12... Tool post 24... Lifting arm 25... Robot hand 31, 33... Chuck mechanism 51, 53... Workpiece stocker 55... Workpiece weight measuring device 58... Weight sensor

Claims

1. A plurality of processing devices that perform processing of the workpiece in the processing chamber; A workpiece transport machine that carries in and out of the processing chamber; a work weight measuring device disposed on a transport route along which the work transport machine transports the work into the processing chamber; A control device that drives and controls the processing device and the work transport device; having The work transport machine is a machine tool equipped with a work transport machine, the drive of which is controlled by the control device in accordance with preset transport conditions based on the value of the work weight measured by the work weight measuring device when the work is brought in.

2. 2. The machine tool with a workpiece transporter according to claim 1, wherein the transport conditions include a transport speed, an acceleration time constant, and a deceleration time constant that are set in accordance with a workpiece weight.

3. 3. The machine tool with a work transporter according to claim 1 or 2, wherein the work transporter transports a work by a robot hand equipped with a plurality of chuck mechanisms, and drive control is performed by the control device in accordance with the transport conditions determined by the work weight and the number of workpieces.

4. 2. The machine tool with a work transporter according to claim 1, wherein the control device determines whether or not the work is suitable for being carried into the machining chamber by the work transporter, based on the value of the work weight measured by the work weight measuring device.

Images