GB2198515A - Lampshade manufacture - Google Patents

Abstract

There is disclosed a jig 10 for holding a lampshade frame 12 while a covering 15 is applied externally to the frame, is tensioned over the frame and is then secured to the frame. The jig comprises a first support 11 on which the frame 12 can be fixedly mounted, a second support 13 spaced from the first support and carrying a gripping device for engaging and for gripping a projecting margin 14 of the covering after application of the latter over the frame, means permitting relative movement between the first and second supports, and means 24 to separate the first and second supports, when the covering is gripped by the gripping device, so that the covering is tensioned over the frame 12. The gripping device comprises a number of individual grippers 16 circumferentially spaced apart and each having a receiving groove 18 into which the respective covering position can be inserted during application of the covering to the frame, and each gripper is movable between a receiving position in which access to the receiving groove is permitted and a gripping position in which the respective covering portion in the groove is firmly gripped. A power operated device (not shown) is coupled with all of the grippers 16 to move the latter jointly from the respective receiving position to the gripping positions. <IMAGE>

Description

LAMPSHADE MANUFACTURE This invention relates to the manufacture of lampshades.

As is well known, lampshades usually comprise a metal wire frame over which a fabric or other covering is taken, the covering being first tensioned and then secured to the component parts of the frame. For very many years, lampshade production has involved manual skills in the application and securement of the covering to the frame, and the quality of the finished product is therefore entirely dependent upon the skill and attention of each individual operative.

Therefore, until fairly recent times, lampshade production has been mainly of a "craft" nature, and though there is factory production of lampshades, this still depends mainly upon manual skills of the individuals.

There have been attempts to "automate" the production of lampshades, with a view to reducing the skill input requirement i.e. to "de-skill" the production, so that lampshades can be produced with a substantially constant quality and on a mass production basis. However, to date, the attempts have involved the use of specially designed, but somewhat crude, jigs which hold the frame while the covering is applied manually to it, and then the jig tensions the covering over the frame.

In order to tension the covering, the jig is provided with prongs which pierce the covering, and then the jig is operated to move the lampshade frame away from the prongs in order to tension the covering. The piercing engagement of the prongs with the covering, which is usually a fabric covering, is rather crude, and is liable to tear the fabric. In addition, it has been necessary for the operatives physically to engage the fabric with the prongs, and this has given rise on a number of occasions to personal injury, bearing in mind (a) that the prongs have sharp tips, and (b) that the location of the prongs is such that they are not readily accessible, nor clearly visible.

Accordingly, the present invention has been developed primarily with a view to providing an improved production rate of lampshades, while maintaining a readily repeatable quality standard which is not entirely dependent upon individual manual skill and attention of an operative.

According to the invention there is provided a jig for holding a lampshade frame while a covering is applied externally to the frame, is tensioned over the frame and is then secured to the frame, in which the jig comprises a first support on which the frame can be fixedly mounted, a second support spaced from the first support and carrying a gripping device for engaging and for gripping a projecting margin of a covering after application of the latter over the frame, means permitting relative movement between the first and second supports, and means operable relatively to separate the first and second supports, when the covering is gripped by the gripping device, so that the covering is tensioned over the frame, in which:: the gripping device comprises a number of individual grippers circumferentially spaced apart and each engageable with a respective portion of the projecting margin of the covering, each gripper defining a receiving groove into which the respective covering portion can be inserted during application of the covering to the frame; each gripper is movable between a receiving position in which access to the receiving groove is permitted and a gripping position in'which the respective covering portion in the groove is firmly gripped; and a power operated device is coupled with all of the grippers to move the latter jointly from the respective receiving positions to the gripping positions.

A jig according to the invention enables the production of lampshades to be at least partly automated, and especially in the part of the production which has hitherto required individual manual skills of an operative, namely the tensioning of the coverings. Thus, the jig can be operated so as to maintain a substantially constant quality, in that it engages a covering and tensions it in a repeatable manner.

The securement of the covering (while maintained under tension) may be achieved in any convenient manner, and one preferred means is the use of specially designed liquid adhesives which can be injected through the covering and into contact with the underlying frame components, and which set so as to secure the covering to the frame components without any staining of the covering. This adhesive is known as a CYONOACRYLATE type adhesive.

During tensioning of the covering, when the projecting margin is gripped and relative separation of the supports takes place, preferably by moving the first support upwardly away from the second support, it is necessary for the arrangement to be such that the covering provides resistance to the tensioning forces. This may be achieved quite simply. For example, in the case of a lampshade which is generally dome-shaped or convergent towards the upper end of the lampshade and underlying frame, the covering will be formed with a shape generally conforming to the shape of the frame, and therefore the application of tension forces to the covering via the grippers will be resisted by the engagement of the covering with the frame.

However, if desired, temporary grippers may be provided in order to clamp the covering to the upper end of the frame.

This will be necessary, for example, when a lampshade design is non-convergent towards the upper end e.g. a cylindrical lampshade.

To further improve the tensioning of the covering, the jig may be provided with a movable head which is engageable with a portion of the covering which initially covers the usual aperture at the upper end of a lampshade frame, so as to press this portion slightly inwardly, thereby to further tension the covering.

After completion of securement of the covering to the frame, it is necessary to trim any excess covering material. This may be carried out by manual trimming with a knife, or it may be carried out mechanically by provision of a cutting device on the jig which is brought into engagement with the excess material and cuts it as the jig rotates. In addition, automatic gluing device(s) may be incorporated in the jig, for application to the covering material at positions where the frame components are over lain.

Conveniently, said means operable relatively to separate the first and second supports comprises a pneumatically operated device, which is operable both to separate the supports during covering tensioning, and also to advance the supports relatively towards each other when the covering has been secured to the frame.

Also, the power operated device which is coupled with the grippers is preferably a further pneumatically operated device, which is operable to move the grippers from the receiving position to the gripping position during gripping engagement with the covering, and thereafter from the gripping position to the receiving position when the covering has been secured to the frame.

Preferably, each gripper takes the form of a fixed jaw and an off-centre roller which is pivotally adjusted about its axis of rotation during movement between the receiving position and the gripping position. To initiate pivotal movement of the rollers, respective transmission rods may be provided, one coupled with each roller, the rods being movable jointly by a pneumatic ram during operation of the gripping device.

The grippers are circumferentially spaced apart from each other, in an arrangement generally conforming with the shape of the lower edge of the lampshade frame. When the lower edge of the lampshade frame is circular, there will be a circular array of grippers, and the number of grippers will depend upon the number of separate "panels" of the lampshade frame, as well as the required degree of tension. Conveniently, up to 16 individual grippers may be provided.

To enable the jig readily to be adapted to be used with different designs and/or sizes of lampshade, preferably each gripper is adjustably mounted on a common base plate, for movement to a position suitable to conform with the shape of the lower edge of any particular lampshade frame. Preferably, the grippers are mounted for adjustable movement along generally radial mounting grooves provided in the base plate.

One embodiment of jig according to the invention, for use in the manufacture of a lampshade, will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side view from one side of the component parts of a jig according to the invention, with a lampshade frame mounted thereon; and, Figure 2 is a diagramatic plan view of a gripping device of the jig.

Referring now to the drawings, a jig according to the invention is designated generally by reference 10 and is intended for use in holding a lampshade frame while a covering is applied externally to the frame, is tensioned over the frame and is then secured to the frame. The jig 10 comprises a first support 11 on which a metal wire lampshade frame 12 is fixedly mounted, a second support 13 spaced from the first support and carrying a gripping device for engaging and for gripping a projecting margin 14 of a lampshade covering 15 (shown in dashed outline in Figure 1) after application of the latter over the frame 12.

Means is provided which permits relative movement between the first support 11 and the second support 13, and a pneumatically operated device (not shown) is provided on the jig which serves relatively to separate the first support 11 from the second support 13, when the covering 15 is gripped by the gripping device (described in more detail below), so that the covering is tensioned over the frame 12.

The gripping device comprises a number of individual grippers 16 which are circumferentially spaced apart on the support 13 and each is engageable with a respective portion of the projecting margin 14 of the covering 15. It will be seen from the drawings that the grippers 16 are arranged in a circular array, generally conforming with the size and shape of the lower end 17 of the lampshade frame 12. In the illustrated embodiment, 16 grippers are provided, and each gripper 16 defines a receiving groove 18 into which the respective portion of the covering 15 can be inserted during application of the covering to the frame 12.

In order to adjust the positions of the grippers 16 to suit a different shape and/or size of lampshade, radial grooves 28 (Figure 2) are arranged in a support plate 21 and along which the grippers 16 can ben adjusted.

Each gripper 16 comprises a fixed jaw 19 and an offcentre or eccentric roller 20 which define between themselves the receiving groove 18. Each gripper 16 is movable between a receiving position, as shown in Figure 1, in which access to the receiving groove 18 is permitted between the fixed jaw 19 and roller 20, and a gripping position in which the respective portion of the covering 15 is firmly gripped between the jaw 19 and the roller 20. A power operated device (not shown) is coupled with all of the grippers 16 to move the latter from the respective receiving positions to the gripping positions. As shown in the diagramatic illustration of Figure 1, the support plate 21 is movable along the axis 22 via a pneumatic ram, in order to pivot all of the rollers 20 via push rods 23 when the mode of operation of the grippers is to be altered.

In the diagramatic illustration of Figure 1, a pneumatic power arrangement for displacing the support plate 21 is shown schematically by reference 24, and this also houses a pneumatically operated device for moving the first support 11 towards and away from the second support 13. In addition, a pusher 29 (shown in dashed outline in Figure 1) lifts the frame 12 during the movement of the support ill away from the support 13.

During operation of the jig, the lampshade frame 12 is fixedly secured onto the first support 11, and then a preformed covering 15 is applied manually over the frame 12 so as to leave a depending margin 14 projecting below the lower edge 17 of the frame 12. The margin 14 is then inserted manually into the receiving grooves 18 of the grippers 16, and then the rollers 20 are pivotted to the gripping positions of engagement with the margin 14. The first support 11 is then moved under pneumatic power away from the second support 13, and this causes the fabric covering 15 to be tensioned over the frame 12. Resistance to these tension forces is provided by virtue of the shaping of the frame 12 and the covering 15, and the engagement therebetween.Once a satisfactory tensioning has been completed, and observed, the covering is then permanently secured to the underlying components of the frame by the use of a liquid adhesive which is injected through the fabric covering and onto the surface of the underlying frame components. Upon setting of this adhesive, the covering is then firmly secured in position.

Excess covering material may then be trimmed, manually with a knife, or by means of an automatically operating cutting device (not shown) provided on the jig.

To further tension the covering, prior to its securement, a pressing device 25 is provided which can be pneumatically powered so as to engage with the crown 26 of the covering 15 in order to press the latter lightly into and through the usual circular aperture 27 defined by the upper end of the lampshade frame 12.

In the event that the covering 15 and frame 12 have a different shape, from the generally dome-shape shown in Figure 1, whereby they no longer converge towards their upper ends, it may be necessary to provide additional means for temporarily holding the covering on the frame during tensioning by the grippers 16. To this end, a temporarily acting gripper may be provided on the jig, to clamp the covering to the upper end of the frame 12.

The jig 10 will normally be oriented at an inclination of its axis to the horizontal, as shown in Figure 1, for the convenience of the operator. The entire jig may rotate about the axis 22, during manual manipulations by the operator, but motor operation may be provided, if required.

The pneumatic control of the grippers 16, and the movement of the frame support 11, may be by means of individual foot pedal switches (not shown), which can readily be controlled by the operator, and thereby result in semi-automated production of lampshades, in a manner which is less dependent upon individual operator skill, as with conventional manual assembly of lampshades, and yet in a readily repeatable manner with simple means.

Claims (13)

1. A jig for holding a lampshade frame while a covering is applied externally to the frame, is tensioned over the frame and is then secured to the frame, in which the jig comprises a first support on which the frame can be fixedly mounted, a second support spaced from the first support and carrying a gripping device for engaging and for gripping a projecting margin of a covering after application of the latter over the frame, means permitting relative movement between the first and second supports, and means operable relatively to separate the first and second supports, when the covering is gripped by the gripping device, so that the covering is tensioned over the frame, in which:: the gripping device comprises a number of individual grippers circumferentially spaced apart and each engageable with a respective portion of the projecting margin of the covering, each gripper defining a receiving groove into which the respective covering portion can be inserted during application of the covering to the frame; each gripper is movable between a receiving position in which access to the receiving groove is permitted and a gripping position in which the respective covering portion in the groove is firmly gripped; and a power operated device is coupled with all of the grippers to move the latter jointly from the respective receiving positions to the gripping positions.

2. A jig according to Claim 1, in which the first support is movable upwardly away from the second support in order to tension the covering.

3. A jig according to Claim 1 or 2, including temporary grippers provided in order to clamp the covering to the upper end of the frame.

4. A jig according to any one of the preceding claims, including a movable head which is engageable with a portion of the covering which initially covers the usual aperture at the upper end of a lampshade frame, so as to press this portion slightly inwardly, thereby to further tension the covering.

5. A jig according to any one of the preceding claims, including a cutting device provided on the jig and arranged to be brought into engagement with any excess covering material in order to cut it as the jig rotates.

6. A jig according to any one of the preceding claims, including an automatic gluing device incorporated in the jig, for application to the covering material at positions where the frame components are overlain.

7. A jig according to any one of the preceding claims, including a pneumatically operated device for separating the first and second supports.

8. A jig according to any one of the preceding claims, in which the power operated device is a pneumatically operated device which is operable to move the grippers from the receiving position to the gripping position during gripping engagement with the covering, and thereafter from the gripping position to the receiving position when the covering has been secured to the frame.

9. A jig according to any one of the preceding claims, in which each gripper takes the form of a fixed jaw and an off-centre roller which is pivotally adjusted about its axis of rotation during movement between the receiving position and the gripping position.

10. A jig according to Claim 9, in which respective transmission rods are provided, one coupled with each roller, and movable jointly by a pneumatic ram during operation of the gripping device in order to initiate pivotal movement of the rollers.

11. A jig according to any one of the preceding claims, in which each gripper is adjustably mounted on a common base plate, for movement to a position suitable to conform with the shape of the lower edge of any particular lampshade frame.

12. A jig according to claim 11, in which the grippers are mounted for adjustable movement along generally radial mounting grooves provided in the base plate.

13. A jig according to Claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawing.