GB2089849A

GB2089849A - Apparatus for machining two parallel edges of a web of material

Info

Publication number: GB2089849A
Application number: GB8138191A
Authority: GB
Original assignee: Texpa Arbter Maschinenbau GmbH
Current assignee: Texpa Arbter Maschinenbau GmbH
Priority date: 1980-12-18
Filing date: 1981-12-18
Publication date: 1982-06-30
Also published as: FR2496722A1; FR2496722B1; GB2089849B; DE3047693C2; DE3047693A1

Abstract

In an apparatus (Figure 1) for machining two parallel side edges of a web (7) which is carried flat through a processing station having sewing devices (12) for each edge, the devices (12) are movable transversely to follow the movements of the edges. Each device (12) is mounted on a carriage (16) and each carriage mounts a motion-controlling light barrier device (34). Each carriage (16) carries its own electric drive motor and the carriage drive (22, 24, 26) comprises a rack (22) and pinions (24), the rack extending transversely from one side of the apparatus to the other. <IMAGE>

Description

SPECIFICATION Apparatus for machining two parallel edges of a web of material This invention relates to an apparatus for machining the two parallel edges of a web of material adapted to be transported substantially flat through a processing station, using on each side a processing apparatus which is displaceable transversely to the direction of transport and parallel to the plane of transport and which follows the edge of the web which is to be processed by it and is arranged for this purpose on a carriage equipped with an independent drive, on which carriage is mounted a light barrier aligned with this edge of the web, said light barrier controlling an electric motor of the drive means in such a manner that the half illumination of its photoelectric element is constantly renewed by the follow-up movement.In known apparatus of this type, the electric motor of the carriage drive is fixed to the installation at the lateral end of the range of displacement of the processing apparatus. The motor shaft rotates a worm gear spindle having the end remote from the motor fixed at the centre of the apparatus. Seated on this spindle is a nut which is solidly connected with the carriage and converts the rotation of the spindle into a movement of translation of the carriage and hence of the processing device.

One disadvantage of these known apparatus is that each processing device cannot move from its own side of the apparatus beyond the middle of the apparatus to the otherside because the two worm gear spindles end at the common spindle bearing situated in the middle of the apparatus between the two sides thereof. The web of material which is to be machined must therefore be brought to the apparatus with its mid-line all the more accurately on the mid-line of the apparatus the narrower the web of material.If the material is fed into the apparatus with a sideways shift, i.e. eccentrically, the processing device mounted on that side of the apparatus which is less fully covered by the material may be unable to be shifted sufficiently far over to the other side of the apparatus because its carriage or the spindle nut associated with it is liable to be stopped at the central spindle bearing before reaching the required position.

It is therefore an object of the present invention to provide an apparatus of the type mentioned above which does not have this disadvantage and which can easily machine the web of material regardless of the width of the web and the position at which it enters the apparatus.

To solve this problem according to the invention, the carriage of each processing device carries the electric motor of its own drive and the said drive has a rack and pinion gear whose rack extends transversely to the direction of transport from one side of the apparatus to the other. This has the advantageous result that both processing devices, whose mean distance apart during operation of the apparatus is equal to the width of the web of material to be treated, can be displayed beyond the centre of the apparatus so that even narrow webs of material can be processed even if they are transported eccentrically. Moreover, the movement of a processing apparatus following the web of material would not be stopped before or when reaching the centre of the apparatus as is liable to happen in known apparatus.

In a preferred embodiment of the apparatus according to the invention comprising an electric proportional action controller provided on each side between the photoelectric element of the light barrier acting as sensitive element and the electric motor of the drive acting as correcting element, the said proportional action controller is equipped with a derivative controlled action, that is to say the control device produces on the control path an action which is proportional to the rate of change of the controlling factor. This action is particularly advantageous because the following movement of the processing device is more rapid and therefore more accurate than in the case of the proportional controls without derivative action used in the known apparatus, which tend to under-control or over-control according to their adjustment.It has hitherto been attempted to overcome this defect by using transmission motors with a high reduction ratio for the carriages of the processing apparatus. However, the speed at which the processing apparatus could follow the edge of the material was always liable to be insufficient.

In the preferred embodiment, the electric motors are direct current motors, which are particularly easy to control.

In the preferred embodiment, the light barrier is mounted on the carriage to be adjustable in the direction of displacement of the processing apparatus so that the light barrier can easily be correctly aligned to the edge of the selvedge from the start. In the preferred embodiment, the two rack and pinion gears have a common rack, which reduces the cost of manufacture of an apparatus according to the invention.

The invention will now be described in detail with reference to a preferred embodiment illustrated by way of example of the apparatus according to the invention for machining the two parallel edges of a web of material. In the drawings, Fig. 1 is a broken off view of an embodiment seen partially from the front: Fig. 2 is a top plan view of the parts shown in Fig. 1 together with a web of material and Fig. 3 is the block circuit diagram of a portion of the control circuit of the embodiment.

The embodiment consists of an apparatus for simultaneously hemming and stitching the two parallel edges 5 of a web of knitted or woven fabric 7 which is adapted to be carried flat and horizontally in its longitudinal direction through a hemming and sewing station illustrated in Figs. 1 and 2. The transport device (not shown) for the fabric 7 is preferably constructed as disclosed in Application No. P 30 47 686.9.

As illustrated in Figs. 1 and 2, the embodiment comprises two halves which are bilaterally symmetrical about a vertical plane 10; the horizontal direction of conveyance of the fabric 7 extends parallel to this vertical plane and the fabric lies with its midline on this plane if it is fed centrally into the apparatus. Only one half of the apparatus will therefore be described in detail.

The edges 5 of the fabric are hemmed by means of a funnel shaped hemming machine (not shown) which folds the edge. Sewing the folded edges 5 of the fabric is then carried out using an industrial sewing machine 12 which together with its drive motor 14 is mounted on a sliding carriage 1 6 equipped with four rollers 1 8 with which it moves on two parallel rails 20 extending from one side of the apparatus to the other perpendicularly to the plane 10. The sewing machines 12 which constitute the two processing apparatus can therefore be reciprocally displaced perpendicularly to the plane 10 and transversely to the direction of transport.The rear (upper in Fig. 2) rail 20' has a parallel rack 22 which is functionally connected with a pinion 24 mounted on the shaft of a direct current motor 26 which is also fixed to the carriage 1 6. Rotation of the motor shaft in the one or other direction therefore causes displacement of the sewing machine 12 towards the centre or back to its own side of the apparatus. The two rack and pinion gears 24, 22 have a common rack 22.

A U-shaped cantilever arm 28 is attached in front of the carriage 16. Mounted on this arm is a plate 30 of adjustable height having at its upper end an adjustment device 32 by means of which a prismatic light barrier 34 can be adjusted relative to the carriage 1 6 by horizontal displacement perpendicular to the plane 1 0. The commercially available light barrier 34 operates with a rectangular beam path between a source of light and a photoelectric element (cell) produced by reflection at the edge 5 of the fabric.

When the photoelectric element of the light barrier 34 which acts as sensitive element is half illuminated, said light barrier 34 transmits an electric normal signals to a proportional plus derivative controller (PD controller) 36, which in turn transmits an electric control signal to the direct current motor 26, as illustrated in Fig. 3. As soon as the half illumination of the photoelectric element of the light barrier 34 is lost due to sideways migration of the slevedge edge 9 of the fabric 7, the motor 26 is controlled by the light barrier 34 by way of the controller 36 so that the light barrier 34 follows the movement of the selvedge and consequently the half illumination of its photoelectric element is re-established. This means that the sewing machine 12 follows the sideways movement of the edge 9 of the fabric 7 so that hemming and stitching can proceed uninterruptedly.

As a deviation from the exemplary embodiment described here, each of the two rack and pinion gears 22, 24 may have its own rack 22. The two motors 26 with pinions 24 would then be mounted on the carriages 1 6 to move in parallel but opposite directions.

Claims

1. Apparatus for machining the two parallel edges of a web of material which is adapted to be carried substantially flat through a processing station, using for each edge a processing device adapted to be displaceable transversely to the direction of transport and parallel to the plane of transport, which processing device is adapted to follow the movement of that edge of the material which is to be processed by it and is arranged for this purpose on a carriage equipped with an independent drive, on which carriage is mounted a light barrier aligned to this edge of the material, which light barrier controls an electric motor of the drive so that the half illumination of its photoelectric element is constantly renewed by the movement following the edge of material, characterised in that each carriage (1 6) of a processing device (12) carries the electric motor (26) of its own drive (26, 24, 22), and said drive comprises a rack and pinion gear (24, 22) with a rack (22) extending transversely to the direction of transport from one side of the apparatus to the other.

2. Apparatus according to claim 1, characterised in that the two rack and pinion gears (24, 22) have a common rack (22).

3. Apparatus according to claim 1 or claim 2, each having an electric proportional action controller between the photoelectric element of the light barrier acting as sensitive element and the electric motor of the drive acting as correcting element, characterised in that the proportional action controller (36) is equipped with derivative control means.

4. Apparatus according to one of the claims 1 to 3, characterised in that the electric motors are direct current motors (26).

5. Apparatus according to one of the claims 1 to 4, characterised in that the light barrier (34) is mounted on the carriage (16) to be displaceable in the direction of displacement of the processing device (12).

6. Apparatus for machining two parallel edges of a web of material which is to be carried substantially flat through a processing station, using for each edge a processing device displaceable transversely to the direction of transport and parallel to the plane of transport, each processing device being arranged to follow the movement of the relevant edge and is carried for this purpose by a carriage, wherein each carriage carries its own drive motor, the carriage drive comprising a rack and pinion with a rack extending transversely to the direction of transport.

7. Apparatus for machining two parallel wedges of a web of material, the apparatus being constructed and arranged substantially as herein described and shown in the drawing.