GB2224138A

GB2224138A - Manufacturing process control

Info

Publication number: GB2224138A
Application number: GB8922349A
Authority: GB
Inventors: Linda Edge
Original assignee: GEC Electrical Projects Ltd
Current assignee: GE Power Conversion Brazil Holdings Ltd
Priority date: 1988-10-04
Filing date: 1989-10-04
Publication date: 1990-04-25
Anticipated expiration: 2009-10-04
Also published as: GB8823217D0; GB2224138B; GB8922349D0

Abstract

In the automation of garment manufacture, where a batch of garments of one type and size may be followed at very short notice by a batch of another type and/or size, teaching of robots would not be economically viable. In the present system, each robot (1-4) is operated by its own controller (14-17) under overall coordination by a system controller (18). The robots operate in accordance with readily interchangeable programs which are produced off-line (at 23-25), so that the program production does not interfere with the running of the system. <IMAGE>

Description

Manufacturing Process Control This invention relates to the control of manufacturing processes, and particularly to the control of automatic equipment for manufacturing garments or other articles from pieces of fabric.

Garments, such as underclothes and blouses, have previously been manufacturered by passing suitably-shaped pieces of fabric ("cut parts") to a machinist, who then overlays and/or folds them as required, and passes them manually through a sewing machine. The machinist forms seam, binds the edges of the cut parts and adds lace and elasticated waistbands, where necessary. The accuracy of the positioning of the seams relies on the machinist's skill, and nominally-identical garments can finish up having quite wide differences in sizes and shapes.

Systems have been proposed for automating at least a part of the manufacturing process by using a robot to move a cut part to a work station, such as a sewing machine. The movement of the cut part is effected by a "gripper" which is mounted on the output shaft of the robot, and which makes contact with the upper surface of the cut part.

A system has now been devised which relies entirely on a succession of robots and mechanical manipulators to position the cut parts, to overlay and fold them, and to pass them through automatically-controlled sewing machines, so that each garment is accurately sized and shaped.

In known manufacturing processes, robots are Utaught" where they have to move to by running through the manufacturing process, putting the robot wrist in each required position during the course of the process and thereby telling the robot controller the co-ordinates of each required position. The controller can thereafter consistently move the robot to each required position, whenever required, within the limits of repeatability possible for that robot structure. However, if a change in the process is required, the controller must be retaught.

In the automation of garment manufacture, where a batch of garments of one type and size may be followed by a batch of another type and/or size, and so on, at very short notice, such reteaching would not be economically viable.

It is an object of the present invention to provide an improved robot control which does not involve teaching of the robots.

According to the invention there is provided a fabric handling system comprising a plurality of work stations; robot means for moving pieces of fabric from one work station to another; and a system controller which is programmable off-line with data for controlling the robot means and the work stations.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing, which is a schematic plan view of part of a garment manufacturing system.

Referring to the drawing, a garment manufacturing system comprises a number of robots, such as robots 1-4, which are used to move shaped pieces of fabric ("cut parts") round on a work table 5.

The cut parts have to be moved into position at work stations, such as manipulators and sewing machines, for a sequence of folding, overlaying and sewing operations to be performed. As an example, two sewing machines 6 and 7 and two manipulators 8 and 9 are shown, but any other combination of work stations may be involved.

The robots are preferably of the gantry type in which a robot is mounted to slide along a first overhead rail or pair of rails, which is, in turn, mounted to slide along a second overhead rail or pair of rails, orthogonal to the first rail or rails, so that the robot can be moved in x and y directions relative to the table. The output shaft of the robot is substantially vertical and is arranged for upward and downward movement (z motion) and rotation (E motion) about its vertical axis. For the sake of clarity of the drawing, the overhead rails are not shown.

The movement of a cut part is effected by a "gripper", such as the grippers 10-13, which is mounted on the output shaft of the robot, and which makes contact with the upper surface of the cut part, so that movement of the robot causes the cut part to slide on the table to the required position.

Each robot 1-4 is controlled by its respective controller 14-17, but the overall control of the robots is effected by a system controller 18, in accordance with a process control program and taking into account indications from devices (not shown) which monitor the progress of the manufacturing operations.

In an example of part of a garment manufacturing process, a cut part 19 is first taken from a stack 20 of cut parts by a ply separator and feeder 21 and is placed on the table 5. A vision system 22 views the cut part 19 and determines, firstly, whether it is of a suitable size and shape, and then determines its exact position and orientation on the table. As a result of the viewing, the robot 2 moves to the required position for accurate location of its gripper 11 over the cut part 19. The gripper is lowered on to the cut part, and horizontal movement of the robot then causes the cut part to slide over the table to the sewing machine 6. The robot then adjusts the position and orientation of the cut part while the cut part is being fed through the sewing machine. The edges of the cut part are thereby bound. A waistband may also be attached to the cut part at that stage.The robot 2 then moves the cut part away from the sewing machine 6, so that the next process step can be carried out, for example folding of the cut part by the manipulator 8. The robot 2 therefore moves the cut part across the table 5 to a position where it can release the cut part and return to fetch the next cut part, and where the gripper 10 of the robot 1 can be lowered on to the cut part 19 so that it can feed it to the manipulator 8. Subsequently, the robot 3 extracts the folded cut part from the manipulator 8 and feeds it to the sewing machine 7, which sews the side seams. The robot 3 may then move the cut part across the table to a position where the robot 4 takes over movement of the cut part, for example for feeding it to the manipulator 9.

The operation of each robot is controlled by its own controller. The overall operation is coordinated by the system controller 18 in accordance with its software.

In the system of the present invention each program for controlling the speeds and coordinates for the various movements is produced off-line at a separate computer terminal comprising a processor 23, a visual display unit 24, a keyboard 25, a mouse and a tablet. The system controller can therefore be running a program, and thereby producing garments, while a program for producing other garments can be in the course of preparation elsewhere. The off-line system can also be used to define, in the program for a particular garment, the required size and shape of the cut part, the gripper shape, and the required arrangement of seams. Data for these parameters are entered via the keyboard 25 and the mouse by the programmer.The paths to be taken by the robots during the manufacturing steps and control data for the sewing machines and the vision equipment are derived from previously defined data.

Non-control functions can also be provided by the off-line system, such as calculation of the cycle time of the manufacturing process for the particular garment.

The operator of the off-line programming system can define the sequence of operations which is used to assemble a garment. Also he/she defines the line arrangement to be used in manufacture and the interaction of the robots and the manipulator/feeding/sewing devices.

As new assembly shapes are required, they can be generated automatically by the system.

The off-line system can be arranged to simulate a production run to enable the operator to produce optimal conditions for the production line. The simulation can be run at two levels - either a discrete event simulation which enables the complete operation of the line to be observed, or an individual cell simulation which allows detailed observation of the robot path so that potential collisions can be detected.

A link 26 can be provided between the off-line system and the on-line system controller 18 to enable data for any particular style or size of garment to be downloaded into the controller on request.

Although the manufacturing system described above is intended to manufacture garments, a similar system could be used to manufacture other articles from pieces of fabric, such as bed linen or tents.

Claims

1. A fabric handling system comprising a plurality of work stations; robot means for moving pieces of fabric from one work station to another; and a system controller which is programmable off-line with data for controlling the robot means and the work stations.

2. A system as claimed in Claim 1, comprising off-line programming means into which data relating to the pieces of fabric and their required movements can be entered manually.

3. A system as claimed in Claim 2, wherein the off-line programming means is linked to the system controller for data transfer therebetween.

4. A system as claimed in any preceding claim, wherein the work stations include at least one sewing machine.

5. A system as claimed in any preceding claim, wherein the work stations include at least one manipulator for folding the pieces of fabric.

6. A system as claimed in any preceding claim, wherein the control data provided by the off-line programming are updated on-line as the movement of the pieces of fabric proceeds.

7. A fabric handling system substantially as hereinbefore described with reference to the accompanying drawing.

8. A garment manufacturing plant including a system as claimed in any preceding claim.