Work transport conveyor

Abstract

To provide a workpiece transport conveyor that allows the load applied to the escape unit to be relieved. [Solution] A work conveyor comprising: a work conveying mechanism that transports a work placed on a conveying member to a work discharge position by the drive of a conveying motor; an escape unit positioned on the side of the work discharge position in the direction of transport and outside the work conveying path to which the work is transported, and in which stoppers alternately move forward and backward relative to the work conveying path at two locations, front and rear in the direction of transport; and a control device that drives and controls the work conveying mechanism and the escape unit, wherein the control device performs a restriction release movement control, in which, when a work is brought forward against one of the stoppers of the escape unit, the conveying motor is rotated in the reverse direction, and after the stopper away from the work has been retracted, the conveying motor is rotated in the forward direction to move the work forward.

Description

Technical Field

[0001] The present invention relates to a work conveyor for continuously conveying a plurality of workpieces, and includes an escape unit for cutting out the leading workpiece.

Background Art

[0002] In a workpiece processing line, when automatically processing a workpiece on a machine tool, a configuration is adopted in which the workpiece is automatically conveyed using a workpiece conveyor and the workpiece is automatically loaded onto the machine tool using an autoloader. In such a workpiece conveyor, an escape unit is provided in the first conventional example disclosed in Patent Document 1 below. The escape unit has a configuration for cutting out the leading workpiece from a plurality of consecutive workpieces so that the workpiece can be reliably taken out by the autoloader. Thereby, among the continuously fed workpieces, the leading workpiece is separated from the subsequent workpieces with a gap and sent to the workpiece unloading position for supply to the autoloader.

[0003] Further, Patent Document 2 below discloses a technique for cutting out the leading workpiece from a plurality of consecutive workpieces in the same manner. The second conventional example of this document is composed of an upstream conveyor having an inclination by free rollers and a downstream conveyor horizontally arranged with a motor attached to each roller. Then, the leading workpiece located at the head of the row stopped by the gate plate is cut out. Specifically, the driving roller on which the workpiece located behind the leading workpiece is placed is rotated reversely, and after the gate plate in front of the leading workpiece is opened, the driving roller on which the leading workpiece is placed is rotated forward. The gate through which the leading workpiece has passed is closed, the driving roller rotating reversely stops, and when the leading workpiece reaches the workpiece unloading position, the driving roller rotating forward also stops.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] International Publication No. WO2020-059127 [Patent Document 2] Japanese Patent Publication No. 2011-111256 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The workpiece conveying conveyor in the first conventional example described above is a roller conveyor in which multiple rollers are arranged in a state inclined toward the downstream side, and workpieces move on the rollers by their own weight. The escape unit installed therein is configured to temporarily stop the leading workpiece and cut it out from the workpieces behind it. Consequently, there may be multiple workpieces lined up behind the stopped leading workpiece, and in such cases the escape unit will be supporting multiple workpieces, resulting in a large load being applied to the stopper against which the workpieces are making contact. Therefore, the movement of the movable part of the stopper of the escape unit becomes impaired due to supporting a large workpiece load. Furthermore, when heavy workpieces are involved, improvements such as increasing the strength of the escape unit may be necessary.

[0006] The workpiece conveying conveyor in the second conventional example lacks an escape unit like the first conventional example, and the leading workpiece is cut out by controlling the reverse rotation of the drive rollers. However, in the second conventional example, a motor for the conveyor must be provided individually for each of the multiple drive rollers, and these must be rotated forward and backward according to the size of the workpiece. As a result, many conveyor motors are required, which increases costs, and it is considered unsuitable for handling heavy workpieces that are the target of machining by machine tools.

[0007] Therefore, the present invention aims to provide a workpiece transport conveyor that relieves the load of the workpiece applied to the escape unit in order to solve the above problems. [Means for solving the problem]

[0008] The workpiece conveying conveyor according to the present invention comprises a workpiece conveying mechanism that transports a workpiece mounted on a conveying member to a workpiece discharge position by the drive of a conveying motor; an escape unit positioned on the side of the workpiece discharge position in the direction of transport and outside the workpiece transport path to which the workpiece is transported, and in which stoppers alternately move forward and backward relative to the workpiece transport path at two locations, front and rear in the direction of transport; and a control device that drives and controls the workpiece conveying mechanism and the escape unit. The control device performs a restriction release movement control in which, when a workpiece that has come into contact with one of the stoppers of the escape unit is moved forward, the conveying motor is rotated in the reverse direction, and after the stopper that the workpiece has moved away from is moved backward, the conveying motor is rotated in the forward direction to move the workpiece forward. [Effects of the Invention]

[0009] In the workpiece conveying conveyor with the above configuration, the workpiece placed on the conveying member is transported to the workpiece discharge position by the drive of the conveying motor. At this time, the workpiece is stopped by a stopper of the escape unit on the front side in the direction of transport at the workpiece discharge position, but predetermined processing such as cutting is performed by the front and rear stoppers in the direction of transport moving back and forth alternately. At that time, the workpiece conveying conveyor executes a restriction release movement control, and the workpiece that has moved backward by the reverse rotation of the conveying motor moves away from the stopper, and the stopper, now free from the load of the workpiece, moves backward, and then the conveying motor rotates forward, transporting the workpiece forward. Thus, the escape unit moves the workpiece in a way that relieves the load applied to the stopper. [Brief explanation of the drawing]

[0010] [Figure 1] This is a plan view showing one embodiment of a workpiece transport conveyor. [Figure 2] This is a side view showing one embodiment of a workpiece conveying conveyor. [Figure 3] This is a front view showing one embodiment of a workpiece conveying conveyor. [Figure 4]This is a plan view showing the escape unit. [Figure 5] This is a simplified block diagram showing the control system of an automated workpiece transfer machine. [Figure 6] This is a flowchart illustrating the processing steps of a workpiece transport program. [Figure 7] This flowchart illustrates the process of cutting out the leading workpiece W using an escape unit. [Figure 8] This is a flowchart illustrating the process of removing restrictions using an escape unit. [Modes for carrying out the invention]

[0011] An embodiment of the workpiece conveyor according to the present invention will be described below with reference to the drawings. Figures 1 to 3 are a plan view, a side view, and a front view of the workpiece conveyor of this embodiment, and in particular Figure 3 is a front view seen from the downstream side in the conveying direction. The workpiece conveyor 1 is formed with a width dimension that conveys multiple workpieces W in a single line, and in Figures 1 and 2, the conveying direction is from left to right, and it is configured to move the workpieces by a predetermined distance. The workpiece conveyor 1 is assembled on a base 3 fixed to the factory floor with support columns 4 standing perpendicular to it, so that the workpieces W move horizontally at a predetermined height.

[0012] The workpiece conveyor 1 is constructed within a cubic frame 11, with rotating shafts 13 and 14 pivotally supported at the same height at its upstream and downstream ends. The rotating shafts 13 and 14, mounted in the width direction, are rotatably supported by bearings. Sprockets 15 and 16 are fixed to the rotating shafts 13 and 14 at the axial center, which is the central part of the width direction of the workpiece conveyor 1, and a flat chain 17, which is the workpiece conveying member W, is stretched across it. In this embodiment, the workpiece conveyor 1 is constructed with a flat chain 17, so the surface on which the workpiece W is mounted is flat.

[0013] As shown in Figure 1, the flat chain 17 has multiple chain members 170 connected together, with rectangular plate sections 171 having their longer sides as the width direction and the shorter sides arranged side by side. The chain members 170 have connecting sections 172, which correspond to the outer or inner plates that make up the chain, joined perpendicularly to the back side of the plate section 171. The connecting sections 172 are located in the center of the longer side, i.e., in the center of the width direction of the conveyor, and adjacent connecting sections 172, which become the outer or inner plates, are alternately connected by pins. In this flat chain 17, the connecting sections 172 provided on the back side of the plate section 171 on which the workpiece W is mounted, are configured to function as a chain.

[0014] In the workpiece conveyor 1, the upper side of the flat chain 17 is the feed side, moving from the upstream sprocket 15 to the downstream sprocket 16. At sprocket 16, it reverses direction, and the lower side becomes the return side of the flat chain 17. In the workpiece conveying mechanism of the workpiece conveyor 1, a conveying motor 18 is fixed to a support column 4 on the downstream side, and a rotational transmission chain 23 is stretched between a sprocket 21 fixed to the output shaft of the conveying motor 18 and a sprocket 22 fixed to a downstream rotating shaft 14. The rotational output of the conveying motor 18 is transmitted from sprocket 21 to sprocket 22 via the rotational transmission chain 23, and the rotation of the rotating shaft 14 causes conveying by the flat chain 17.

[0015] The workpiece transport conveyor 1 has a workpiece discharge position A set just before the flat chain 17 reverses from the feed side to the return side, and the workpieces transported there are grasped by the robot hand 8 of the auto loader shown in Figure 2. A V-block (V-shape) 5 is provided at the workpiece discharge position A, so that the transported circular workpiece W hits the V-shaped part and is always positioned in a constant position. Furthermore, the workpiece transport conveyor 1 has an escape unit 7 on the front side in the transport direction so that the leading workpiece W is cut out from the rear workpiece W towards the workpiece discharge position A.

[0016] Figure 4 is a plan view showing an escape unit. The escape unit 7 is provided with a first stopper 31 located on the upstream side where the workpiece moves and a second stopper 32 located on the downstream side. The workpiece conveyor 1 is provided with two side guides 25 on both sides in the width direction on the upper surface which is the feed side of the flat chain 17, and the workpiece W is configured to be able to move straight between them. The escape unit 7 is arranged outside on the workpiece conveyance path L sandwiched by the two side guides 25, and the first and second stoppers 31, 32 are configured to enter the workpiece conveyance path L over the side guides 25 and retreat outside.

[0017] The first stopper 31 and the second stopper 32 are detachable claw members at the tip of the slide members 33, 34, and their fixed positions and the size and shape can be changed by replacement. The slide members 33, 34 are slidably assembled to the unit body 35 so as to move in a direction orthogonal to the conveyance direction of the workpiece W. Further, a bracket 37 is fixed to the unit body 35, and an air cylinder 36 is pivotally supported there by a pin 38. The air cylinder 36 has the end of the cylinder tube pivotally supported, and a lever 39 is pivotally attached to the tip of the piston rod 361.

[0018] The lever 39 is pivotally supported at the end opposite to the pivotally attached end of the piston rod 361 by a rotating shaft 41, and is configured to swing by the telescopic operation of the air cylinder 36. Further, the rotating shaft 41 serves as a cam shaft, and a plate cam 42 is fixed inside the unit body 35. The plate cam 42 has cam portions protruding left and right engaged with the recesses of the slide members 33, 34. Therefore, the escape unit 7 is configured such that the lever 39 and the plate cam 42 swing by the telescopic operation of the air cylinder 36, and the slide members 33, that are pushed by the left and right cam portions, 34 perform linear movement in opposite directions. Note that the supply and exhaust of the operating air to the air cylinder 36 are configured to be executed by the operation of an electromagnetic switching valve 19 (see FIG. 5).

[0019] In the work transfer conveyor 1, automatic transfer to the work unloading position A is performed by the movement of the work W by the transfer motor 18 and the cutting out of the leading work W by the escape unit 7. Therefore, in order to execute automatic control of each drive unit, work detection switches for detecting the work W are provided at a plurality of locations. In the work transfer conveyor 1 of the present embodiment, a photoelectric switch is used, and an input work detection switch 45 on the upstream side, a limit work detection switch 46 for operating the escape unit 7, and an unloading work detection switch 47 for detecting the work W existing at the work unloading position A are provided.

[0020] The work transfer conveyor 1 is for feeding the work W to a machine tool located on the downstream side, and is configured to be automatically controlled by a control device provided in the machine tool. However, the work transfer conveyor 1 may be provided with its own control device. FIG. 5 is a simplified block diagram showing a control system of a machine tool including the work automatic transfer machine 1. The control device 50 of the machine tool 10 mainly consists of a computer provided with storage devices such as a ROM 52, a RAM 53, and a non-volatile memory 54 in addition to a CPU 51.

[0021] An I / O port 55 is provided in the control device 50 and is connected to various drive means via a driver (not shown). Therefore, in the machine tool 10, automatic machining of the work W is performed by controlling various drive units 57 such as a chuck device, a tool rest, or a slide mechanism. Further, in this control device 50, in order to automatically transfer the work W to the machine tool 10, automatic control of the drive units of the work transfer conveyor 1 and the autoloader 58 is performed. In particular, in the present embodiment, a work transfer program 61 corresponding to the problems of the work transfer conveyor 1 provided with the escape unit 7 is stored in the memory.

[0022] In a configuration where workpieces W are transported by automatic control, the movable parts must move smoothly. In this regard, in the workpiece transport conveyor 1, the first and second stoppers 31 and 32 of the escape unit 7 are subjected to loads as they receive the incoming workpieces W. Therefore, the load is large for heavier workpieces W, and especially when multiple workpieces W are connected, they are subjected to an even greater load. As a result, the sliding parts 33 and 34 of the first stopper 31 and the second stopper 32 may tilt, causing them to get stuck inside the unit body 35, and this resistance may hinder smooth movement. Therefore, the workpiece transport program 61 is designed to control the movement of the first stopper 31 and the second stopper 32 to release the load of the workpieces W as they move forward and backward.

[0023] Figure 6 is a flowchart showing the processing steps of the workpiece transport program. When the power is turned on, the transport motor 18 of the workpiece transport conveyor 1 starts to drive, enabling the transport of workpieces W. Specifically, the transport motor 18 is driven, and its rotation becomes the rotation of a sprocket 21 fixed to the output shaft, which is transmitted to the rotating shaft 14 via a rotation transmission chain 23 and a sprocket 22. Then, a sprocket 15 fixed to the rotating shaft 14 becomes the driving side, and a flat chain 17 stretched between it and the driven sprocket 14 rotates. Workpieces W are then placed into the rotating flat chain 17 of the workpiece transport conveyor 1 by an operator.

[0024] In the workpiece transport program, the presence or absence of workpieces W is first determined by the workpiece input detection switch 45 (S101). When the workpiece input detection switch 45 detects the input of workpieces W (S101: YES), the total weight of all workpieces from the input position to the escape unit 7 is calculated (S102). The number of workpieces W loaded on the workpiece transport conveyor 1 is increased by "1" upon detection by the workpiece input detection switch 45. The weight of each workpiece W being transported is input by the settings of the machining program during the changeover of the machine tool 10.

[0025] As the flat chain 17 rotates, the workpiece W mounted on it is transported toward the downstream workpiece discharge position A. At this time, the leading workpiece W, as shown in Figure 4, hits the second stopper 32 which has entered the workpiece transport path L beyond the side guide 25, and its movement is hindered. At this time, the presence or absence of workpiece W in the cutting position is determined by the restricted workpiece detection switch 46 (S103). If the presence of workpiece W to be cut out is confirmed (S103: YES), the escape unit 7 performs the cutting process of the leading workpiece W, as will be described later (S104).

[0026] The leading workpiece W after cutting is then transported further forward until it hits the bevel 5 and stops. This position is the workpiece discharge position A, and the presence or absence of the transported workpiece W is determined by the discharge workpiece detection switch 47 (S105). If the presence of the workpiece W to be discharged is confirmed (S105: YES), the number of workpieces W loaded on the workpiece transport conveyor 1 is reduced by "1", and the total weight of all workpieces up to the escape unit 7 is calculated (S106). Then, as will be described later, the restriction removal process by the escape unit 7 is performed in conjunction with the workpiece discharge by the autoloader 58 (S107).

[0027] Next, Figure 7 is a flowchart showing the cutting process of the leading workpiece W by the escape unit 7 (S104), which is one of the restrictions-release movement control methods. In the cutting process of the leading workpiece W, first the drive of the transport motor 18 is stopped, and the rotation of the flat chain 17 stops (S201). At this time, as shown in Figure 4, the movement of the slide member 34 is hindered by the load applied to the leading workpiece W being pressed against the second stopper 32. Therefore, the necessity of reverse rotation to relieve the load is determined according to the total weight of the workpiece W connected to the second stopper 32 (S202).

[0028] Here, if the total weight of all workpieces calculated in step S102 exceeds a preset threshold (S202: YES), the transport motor 18 is controlled to reverse rotation, and the rotation of the flat chain 17 is reversed toward the upstream side (S203). This reverse rotation moves the leading workpiece W backward to a point where it is slightly away from the second stopper 32. Note that even if the workpieces W exceeding the threshold weight are loaded onto the flat chain 17, the workpieces W may be separated from each other. However, in this embodiment, it is assumed that the workpieces W are connected, and the reverse rotation is determined using only the weight value as a parameter.

[0029] Next, the restriction switching process is performed in the escape unit 7 (S204). In the escape unit 7 shown in Figure 4, the second stopper 32, which was holding the leading workpiece W in place, retracts under the control of the air cylinder 36, and conversely, the first stopper 31 moves beyond the side guide 25 and onto the workpiece transport path L, as shown by the dashed line. That is, as the air cylinder 36 contracts from the extended state shown in the figure, the lever 39 swings, and within the unit body 35, the slide member 33 engaged with the plate cam 42 is pushed out, while the slide member 34 is pulled in. As a result, the leading workpiece W, released from the second stopper 32, can move forward, and the next workpiece W located behind it is restricted from moving by the first stopper 31. Then, the transport motor 18 is controlled to rotate in the forward direction, and the flat chain 17 is transported (S205), and the leading workpiece W moves forward, completing the cutting process (S104).

[0030] Next, the leading workpiece W, which has been cut out by the escape unit 7, is removed by the auto loader 58 at the workpiece discharge position A and transported to the machine tool 10. Figure 8 is a flowchart showing the restriction removal process (S107) by the escape unit 7 after workpiece discharge, which is one of the restriction release movement control processes. In the restriction removal process, the presence or absence of workpiece W is confirmed by the discharge workpiece detection switch 47 (S301). After workpiece W has been discharged by the auto loader 58 (S301: YES), the necessity of reverse rotation for load release is determined according to the total weight of workpiece W connected to the first stopper 32 (S302).

[0031] Here, if the total weight of all workpieces calculated in step S106 exceeds a preset threshold (S302: YES), the conveying motor 18 is controlled to rotate in reverse, and the rotation of the flat chain 17 is reversed toward the upstream side (S303). This reverse rotation also moves the leading workpiece W slightly backward away from the second stopper 32, and is determined solely by whether or not the flat chain 17 is loaded with workpieces W exceeding the threshold weight.

[0032] Next, the restriction release process is performed in the escape unit 7 (S304). At this time, the first stopper 31 of the escape unit 7 is hitting the workpiece W and hindering its progress. Therefore, the air cylinder 36 controls the first stopper 31 to retract, allowing the workpiece W to move forward, and conversely, the first stopper 32 moves beyond the side guide 25 and onto the workpiece transport path L as shown in the figure. That is, the air cylinder 36 moves from a retracted state to an extended state as shown in Figure 4, and the slide member 34 engaged with the plate cam 42 is pushed out by its lever 39, while the slide member 33 is pulled in. Then, the transport motor 18 is controlled to rotate in the forward direction, and workpiece transport by the flat chain 17 resumes (S305), and the leading workpiece W moves forward, completing the restriction release process (S107).

[0033] Therefore, according to this embodiment, when the leading workpiece W is cut out (S104) or restricted removal (S107) in the escape unit 7, the transport motor 18 is rotated in reverse to move the workpiece W backward, thereby releasing the load of the workpiece W when the first and second stoppers 31 and 32 move forward and backward. As a result, the escape unit 7 can move the first and second stoppers 31 and 32 smoothly, eliminating the need to increase the strength of the first and second stoppers 31 and 32 in accordance with the load received from the workpiece W, or to change the air cylinder 36 to one with a higher output, thus reducing costs.

[0034] Furthermore, in this embodiment, a control method is employed that assumes the load applied to the first and second stoppers 31 and 32 by the weight of the workpiece W and performs reverse rotation. Therefore, for lightweight workpieces W that have little impact on the first and second stoppers 31 and 32, time loss can be eliminated without reversing the rotation of the transport motor 18.

[0035] Although one embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications are possible without departing from its spirit. For example, in the above embodiment, a pattern was described in which the total weight of the workpiece W is calculated when executing the restriction release movement control, but the transport motor 18 may be rotated in reverse regardless of the weight of the workpiece W. Alternatively, the execution of the restriction release movement control may be switched on or off depending on the weight of a single workpiece without calculating the total weight of the workpiece W. [Explanation of Symbols]

[0036] 1…Workpiece conveyor 5…V-block 7…Escape unit 10…Machine tool 17…Flat chain 18…Conveyor motor 31…First stopper 32…Second stopper 45…Input workpiece detection switch 46…Restricted workpiece detection switch 47…Output workpiece detection switch 50…Control device 61…Workpiece conveying program 170…Chain member

Claims

1. A workpiece transport mechanism that uses a transport motor to transport a workpiece mounted on a transport component to the workpiece discharge position, An escape unit is positioned on the front side in the transport direction of the workpiece discharge position and outside the workpiece transport path in which the workpiece is transported, and a stopper alternately moves forward and backward relative to the workpiece transport path at two locations, front and rear in the transport direction. A control device for driving and controlling the workpiece transport mechanism and the escape unit, It has, The control device performs a restriction-release movement control for a workpiece transport conveyor, which, when a workpiece is pressed against one of the stoppers of the escape unit, reverses the rotation of the transport motor, and after the workpiece has moved away from the stopper, reverses the rotation of the transport motor to move the workpiece forward.

2. The work transport mechanism includes a restricted work detection switch for detecting a work located at a position corresponding to the escape unit, and a discharged work detection switch for detecting a work located at the work discharge position, and the control device performs forward restriction release movement control based on the detection signal of the restricted work detection switch or the discharged work detection switch, as described in claim 1.

3. The workpiece conveying conveyor according to claim 1 or 2, wherein the control device performs forward movement control to release the forward restriction according to the weight of the workpiece being conveyed.

4. The work transport mechanism has a work input detection switch for detecting workpieces to be placed on the transport member, and the control device performs forward restriction release movement control according to the total weight of the workpieces based on the number of workpieces to be transported to the escape unit, as described in claim 3.

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