GB2301300A - A process for producing a display system - Google Patents

Abstract

A display system comprising shelves is produced by producing perforated tubes (using a mandrel) for use as uprights which can support transversely-extending members. The stroke of a press brake is set (12) so that either one face of a tube or two opposed faces may be punched in one punch die stroke. To facilitate this, the mandrel has through-holes and the lower punching surface of the punch dies extend inwardly and upwardly so that it is recessed centrally. After a first set of apertures is punched by five or a sub-set of five punch dies (13), the tube is moved to allow a pivotally mounted guide member to drop successively into each aperture. When the guide member drops into the final aperture (15), the direction of travel of the tube is reversed so that pivotal movement is prevented and a limit position for the tube is reached at which the next punching operation will take place to provide the correct pitch. A very durable coating is achieved by spraying with a polyester coating powder (20) to a thickness of at least 60 microns, the powder having a specific gravity in the range of 1.4 to 1.7. The parts are then baked for approximately 10 minutes at a temperature of approximately 200{C. The parts are then assembled.

Description

ZA process for producing a display system The invention relates to a process for producing a display system of the type for storage and display of articles, generally used in retail outlets.

Production of such systems is a very competitive business and in general the most commercially worthwhile approach is to produce customised display systems to the request of a customer. It is therefore very important to have a production process which has flexibility whereby there are frequent changes in designs. It is, of course, also very important to ensure that production costs are kept to a minimum and that the end product has a very high quality both in terms of structural strength and finishing.

An integral part of display systems which are produced by the process of the invention are uprights which are in the form of steel tubes with apertures or perforations along the length of the tubes. These are used for reception of shelving brackets or cross-struts, etc. In general, it has been found that the most important aspects of the production process to achieve the above-mentioned objectives are efficient and flexible tube punching and also the application of a high quality finish to the system. European Patent Specification No. EP 249,862 (Stockrail Services Limited) describes an apparatus for producing punched tube. In this apparatus, there is a single punch die. In front of this die, there is a guide pin mounted on the same block as the punch die, the guide pin having a chamferd lower surface in order to provide a lead-in to an aperture in the mandrel.A gear transmission arrangement is provided for moving the tube.

While such an apparatus appears to be quite effective for the processes described in the specification, where a very high efficiency is required in an environment whereby the punching requirements change very frequently, it would appear to be inefficient. Further, because of the drive arrangement, there appears to be a significant set-up time. British Patent Specification No. GB 2075403 describes a system whereby a punching operation is operated in synchronism with a chain drive for the tube.

Such an arrangement is quite complex and it would appear that comprehensive maintenance would be required to ensure that synchronism is always maintained. It also appears that where there are frequent design changes, lead times may be excessive. An apparatus is described in British Patent Specification No. GB 2024690 (Rohrtechnik) in which pairs of opposed punches are used for punching opposed apertures in a tube. This apparatus appears to be quite effective, however, again it may be inefficient in situations where there are short batch runs which are frequently changed. Various other apparatus for punching apertures in tubes are described in US 4,052,878, US 3815399, US 3,738,209, US 3,376,725, and DE 2,632,713.

None of these specifications appear to be effective at providing a high efficiency with a very good quality where there are very frequent batch changes with short batch runs.

Regarding the finishing of shelving systems, it has conventionally been the case that these are spray painted after production. In many environments, this coating technique is effective, however, where there is prolonged exposure to sunlight or outdoor use, it has been found that the coating deteriorates over time.

The invention is directed towards providing a production process which produces a very high quality customised product with high efficiency.

According to the invention, there is provided a process for producing a display system, the process comprising the steps of: stamping sheet metal to produce display system planar parts; sliding a steel tube over a floating mandrel having through-holes extending between opposed upper and lower faces thereof and being connected to an elongate support rod extending through the tube; setting the stroke of a press brake driving a set of punch dies associated with the mandrel to either a single wall or double wall punch stroke; aligning the tube with the punch die for a first punching operation and punching a first set of apertures adjacent one end of the tube; aligning the tube for correct aperture pitch by sliding it over the mandrel until a guide member which is mounted on a stripper plate engages the innermost punched aperture;; punching a second set of apertures at this tube position; repeating the aligning and punching operations until the tube has had all desired apertures punched; coating the planar parts and the tube by spraying with a powder coating and subsequently baking to adhere the coating and subsequently assembling the parts and the or each tube to provide a display system.

Preferably, the guide member is mounted for pivotal movement about an axis transverse to the direction of tube travel.

In one embodiment, the guide member has a tapered leading surface and a substantially perpendicular trailing surface, and the process comprises the step of reversing movement of the tube for abutment of an aperture edge against the trailing surface to provide a limit position for punching.

Preferably, the limit position is reached when further pivotal movement of the guide member is prevented by a fixed stop.

In another embodiment, there are at least four punch dies in the set of punch dies.

In a further embodiment, each punch die is secured to a plate by use of a releasable fastener whereby punch dies may be removed to vary pitch.

Preferably, the coating powder is a polyester coating powder which is applied by use of an electrostatic spray gun in a heated atmosphere.

In another embodiment, the ambient temperature during spraying of the polyester coating powder has a temperature in the range of 25 to 300C.

In one embodiment, the polyester coating powder has a specific gravity in the region 1.4 to 1.7 applied to a thickness of 60 to 70 microns.

Preferably, the baking temperature is in the range of 195 to 2050C and the time duration is 9.5 to 10.5 minutes. The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a flowchart illustrating a process of the invention; Fig. 2 is a front view of a press brake used for punching apertures in tubes such as those also illustrated in Fig. 2; Fig. 3 shows a press station in more detail; Fig. 4 is a detailed and partially cut-away front view of the press station; Fig. 5 is a cross-sectional side view of the punch head; Fig. 6 is a perspective view showing an initial coating stage; Fig. 7 is a perspective view showing a coating drying stage; and Fig. 8 is a perspective view showing a typical display system end product.

Referring to the drawings, Fig. 1 shows an overview of a production process of the invention, Figs. 2 to 7 illustrate some of the production stages in detail, and Fig. 8 shows a typical end product. The process is indicated generally by the reference numeral 1 and comprises steps 10 to 22 inclusive. In step 10 of the process, planar members for display systems are stamped using stamping of press brake machines. Such members may be brackets such as the brackets 73 and 75 or a crossstrut such as that illustrated at 74 in Fig. 8. There may be additional crimping and bending operations carried out using press machines and the required tooling. The shapes and sizes of the brackets which are produced are determined whereby relatively long production runs may be used for the stamping operations as an individual bracket design may be used in a wide variety of customised shelving systems.In this way, single bracket designs such as the bracket 73 may be used for a wide variety of different shelving systems such as the system 70 while a major change between the different systems would be different constructions of uprights 71 with different spacings between apertures, different sizes of tube, etc.

It has been found to be best to use a single size aperture to the fullest extent possible while varying the spacing or pitch between system where this is required.

As described below, the process provides a very effective way of efficiently punching tube to produce uprights such as the uprights 74 in a manner whereby the spacings or pitch may be easily changed between batches.

Part of the tube 30 which is purchased is shown in Fig. 2 and the tube when punched is indicated by the numeral 31.

A press brake machine 32 for forming the punching operation is also shown in Fig. 2 and this comprises a support frame 33, a belt drive wheel 34, a crank mechanism 35 and a punch head 36. The press brake 32 has a clutch arrangement to disconnect the drive from the punch head 36 while the tube 30 is moved. As shown in more detail in Figs. 3 to 5 inclusive, the punch head 36 is shown punching a tube 37. The punch head 36 comprises a base plate 38 supporting guide pillars 39 on which a top plate 40 moves in a reciprocating up and down motion. The punch head 36 also comprises a front guide member 41 and a top stripper plate 42. A floating mandrel 43 is mounted within the tube 37 and this is connected to an elongate support rod 44 which runs through the tube 37 and extends out the far end. This is shown most clearly in Fig. 3.

The stripper plate 42 has apertures 46 for reception of press dies which move through the apertures 46 and punch the tube 37, the upper face being supported by the mandrel 43. A guide member 47 is mounted at the rear end of the stripper plate 42 and this is pivotally mounted about a pivot pin 46 for pivotal motion about an axis transverse to the direction of travel of the tube 37. Finally, the punch head 36 comprises a set of five punch dies 49 connected to the top plate 40. As shown most clearly in fig. 4, the lower surfaces of the punch dies 49 are tapered inwardly and upwardly from the extremities in the direction of travel of the tube 37.

To punch the tube 37, it is initially pushed over the support rod 44 and the mandrel 43 until one extremity is over the mandrel 43. In step 12, the stroke of the punch head 36 on the press brake 32 is set for either one or two simultaneous punching operations. In the embodiment described, there is only one punching operation whereby apertures are punched in the top face of the tube 37.

However, the stroke may be set so that the punch dies 49 proceed downwardly to punch apertures in the bottom face of the tube 37. This is facilitated by the construction of the mandrel 43 whereby it has through-holes extending between its top and bottom surfaces, and also by the strength and lower surface configuration of the punch dies 49.

In step 13, the tube 37 is aligned with the punch tools 49 by use of a datum on the base plate 38 or the stripper plate 42 for the first punching operation. The drive on the press brake 36 is activated so that the top plate 40 moves downwardly to cause the five punch dies 49 to punch five apertures simultaneously in the top surface of the tube 37. Again, the configuration of the mandrel and of the punch dies 49 allow punching of five holes simultaneously, thereby providing a high efficiency.

However, where a different pitch is required between apertures, alternate punch dies 49 may be removed very easily beforehand. In step 14, the tube 37 is moved to the right as viewed in Fig. 4. During this movement, the guide member 48 pivots in the anti-clockwise direction because its leading surface (which is tapered) engages the moving edge of an aperture. When it is over the next aperture, it falls into this aperture and as the leading edge of that aperture engages the tapered surface it rotates in the anti-clockwise direction again. Finally, when the guide member 47 drops into the last-punched aperture, the operator moves the tube 37 in the reverse direction as indicated by the arrow A of Fig. 4 so that the trailing edge of the guide member 47, which is substantially perpendicular prevents further movement in the direction of the arrow A.This feature is also brought about by virtue of a stop on the stripper plate 42 which prevents the guide member 47 rotating in the clockwise direction beyond a position whereby the trailing edge is vertical. The horizontal distance between the guide member 47 and the punch dies 49 is set to the correct pitch so that if the tube 37 remains at this limit position, the next punching operation will take place at the correct location. A very high degree of flexibility is achieved by virtue of the fact that the stripper plate 40 may be very easily changed to one of a different configuration whereby this distance is different.

Accordingly, it will be appreciated that the pitch may be very easily controlled by a simple control of the number of punch dies 49 within the relatively large set of five and also by use of different stripper plates 42 and associated guide members. The action required to locate the tube 37 correctly is extremely simple and may be done either manually or by a simple drive mechanism, depending on the volumes involved. The important point is that changes between different batches may be made very quickly with short lead times.

The steps of the guide member 47 engaging the tube 37 is indicated by the step 15 of Fig. 1 and the reverse movement to the limit position is indicated by the step 16. The punching operation is indicated by the step 17 and as indicated by the decision step 18, the movement, positioning and punching operations are repeated until the end of the tube is reached.

Another important aspect of the invention is the manner in which the various parts are finished. All of the parts including the brackets, the uprights and any other struts, etc. are coated individually. The steel which is used to produce them is a mild steel having a semi-bright surface.

This steel is marketed under the trade reference CR4 and has been found to be particularly suitable for coating using the powder coating technique. Further, if necessary, the steel may be galvanised if this is required. In step 19, the individual parts are coated with a powder coating in a chamber 50. The chamber 50 is heated to a temperature of 25"C to 30"C with a slow-moving air stream recirculated by a fan 59. Overhead support bars 51 are mounted in the chamber 50 and steel hooks 52 are used to support the parts, indicated by the numerals 53 and 54. A powder coating application apparatus 55 is then used and this comprises a powder drum 56, a control unit 57, and a powder gun 58.The apparatus 55 acts to provide an electrostatic charge on the powder coating as it is being discharged through the gun 58 for adherence to the parts 53 and 54. It has been found that a polyester powder having a specific gravity in the range of 1.4 to 1.7 is particularly suitable at providing a very strong and durable finish and also at accessing all of the exposed surfaces of the parts such as the side edges of the apertures. A relatively short spray time of 5 to 10 seconds provides a coverage of at least 60 microns. It has been found that by spraying in the atmosphere provided by the chamber 50, adherence is particularly effective.

Immediately after spraying, the parts 53 and 54 are conveyed to an oven 60 having overhead support bars 61 and hooks 62 from which the parts 53 and 54 are suspended.

Gas burners 55 provide a bake temperature of approximately 200"C, although a temperature in the range of 195 to 205"C has been found to be satisfactory. The bake time is in the region of 9.5 to 10.5 minutes. By baking in this manner, it has been found that the coating is extremely durable over a prolonged period of time, even for outdoor use and an extensive exposure to sunlight. It has also been found that there is very effective coating of all exposed edges, even those which are difficult to access.

The spraying and the baking steps are indicated by the numerals 20 and 21 in Fig. 1. Finally, in step 22, the various parts are assembled according to the customer requirements to produce a display system such as that indicated by the numeral 70 in Fig. 8. In addition to the parts previously described, the system 70 comprises parts 72a and 72b which are produced by both stamping and bending operations. The same coating techniques are used for all of these parts.

The invention is not limited to the embodiments hereinbefore described, but may be varied in construction and detail.

Claims (12)

1. A process for producing a display system, the process comprising the steps of: stamping sheet metal to produce display system planar parts; sliding a steel tube over a floating mandrel having through-holes extending between opposed upper and lower faces thereof and being connected to an elongate support rod extending through the tube; setting the stroke of a press brake driving a set of punch dies associated with the mandrel to either a single wall or double wall punch stroke; aligning the tube with the punch die for a first punching operation and punching a first set of apertures adjacent one end of the tube; aligning the tube for correct aperture pitch by sliding it over the mandrel until a guide member which is mounted on a stripper plate engages the innermost punched aperture; punching a second set of apertures at this tube position;; repeating the aligning and punching operations until the tube has had all desired apertures punched; coating the planar parts and the tube by spraying with a powder coating and subsequently baking to adhere the coating and subsequently assembling the parts and the or each tube to provide a display system.

2. A process as claimed in claim 1, wherein the guide member is mounted for pivotal movement about an axis transverse to the direction of tube travel.

3. A process as claimed in claim 2, wherein the guide member has a tapered leading surface and a substantially perpendicular trailing surface, and the process comprises the step of reversing movement of the tube for abutment of an aperture edge against the trailing surface to provide a limit position for punching.

4. A process as claimed in claim 3, wherein the limit position is reached when further pivotal movement of the guide member is prevented by a fixed stop.

5. A process as claimed in any preceding claim, wherein there are at least four punch dies in the set of punch dies.

6. A process as claimed in claim 5, wherein each punch die is secured to a plate by use of a releasable fastener whereby punch dies may be removed to vary pitch.

7. A process as claimed in any preceding claim, wherein the coating powder is a polyester coating powder which is applied by use of an electrostatic spray gun in a heated atmosphere.

8. A process as claimed in claim 7, wherein the ambient temperature during spraying of the polyester coating powder has a temperature in the range of 25 to 300C.

9. A process as claimed in claim 7 or 8, wherein the polyester coating powder has a specific gravity in the region 1.4 to 1.7 applied to a thickness of 60 to 70 microns.

10. A process as claimed in any of claims 7 to 9, wherein the baking temperature is in the range of 195a to 205cm and the time duration is 9.5 to 10.5 minutes.

11. A process substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.

12. A display system whenever produced by a process as claimed in any preceding claim.