GB2090178A

GB2090178A - A process and apparatus for making holes through a sandwich element

Info

Publication number: GB2090178A
Application number: GB8133119A
Authority: GB
Original assignee: Crawford Door AB
Current assignee: Crawford Door AB
Priority date: 1980-11-17
Filing date: 1981-11-03
Publication date: 1982-07-07
Also published as: FI813626L; DE3144025A1; NO813872L; NL8104916A; DK505681A; BE891118A; SE8008047L; FR2494168A1

Abstract

A process for making a hole through a sandwich element comprises passing through the element a punching tool which has a punching blade 18 equipped with pointed teeth and extending along the desired cutting line of the hole, and with a substantially straight side 23 following the desired cut edge and extending in the movement direction of the punching tool relative to the workpiece, and with reducing thickness towards the side edges (24B) and points (24A) of the teeth (24). The invention also includes apparatus suitable for carrying out the process. <IMAGE>

Description

SPECIFICATION A process and apparatus for making holes through a sandwich element The present invention relates to a process and apparatus for making holes through a sandwich element, particularly an element of this type which is formed from plate-like sheets of a hard material such as metal, for example, consisting of aluminium, with an intermediate filling of compressible material.

A time-consuming and expensive process for making cut-outs, for example, for door windows or lock mechanism, has already been used in the manufacture of doors, for example, which are formed by a composite sandwich element. These cut-outs were sawn out in order to obtain smooth and precise edges around the hole made and in order not to deform the element; however, this was a time-consuming and expensive process according to, amongst other things, the shape of the cut-out required, for example, if its corners were curved, etc. It has already been found impossible to punch out such holes in sandwich elements with conventional punching tools, due, amongst other thing to the compressible filling material in the element which deformed the element during attempts at punching with conventional punching devices.

The present invention seeks therefore to provide a process of the kind indicated above which is quick and inexpensive, and to provide apparatus for carrying out this process.

According to a first aspect of the invention, there is provided a process for making a hole through a sandwich element wherein a punching tool which has a punching blade equipped with pointed teeth and extending along the desired cutting line of the hole, and with a substantially straight side following the desired cut edge and extending in the movement direction of the punching tool relative to the workpiece concerned, and with reducing thickness towards the side edges and points of the teeth is passed right through the element.

According to a second aspect of the invention, there is provided apparatus for making a hole through a sandwich element comprises a punching tool which has a punching blade equipped with pointed teeth and extending along the desired cutting line of the hole, and with a substantially straight side following the desired cut edge and extending in the movement direction of the punching tool relative to the workpiece concerned, and with reducing thickness towards the side edges and points of the teeth.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Fig. 1 is a perpendicular view of an apparatus which is intended for making holes through a sandwich element, Figs. 2 to 4 show different phases of a holecutting process; Fig. 5 show a punching tool part appertaining to the apparatus, viewed obliquely from the front; Fig. 6A shows the punching tool part viewed directly from below; Fig. 6B shows the punching tool part viewed directly from the front, and Fig. 6C a cross-section through the punching tool part.

The apparatus shown in Figure 1 and designed to produce holes, for example, in the form of cutouts in sandwich elements, particularly when such a sandwich element 1 is formed by sheets made, for example, of a metal such as aluminium and put together with an intermediate layer of filling material of the compressible type, is supported on a machine stand 2 which is shown only partially in Figure 1. A base part of the apparatus is formed by a baseplate 3 which is supported by two linear beams 4 which are supported in turn by crossbeams 5 mounted on the stand, thereby forming a feed path on the upper side of a plate or sheet 6 laid on the said cross-beams 5.

The baseplate 3 on which there rests a die 7, these parts 3, 7 being rectangular, bears at each corner a column element 8 which is connected rigidly by one end to a column-mounting part 9 but has its other end movably mounted in a column-displacing element 10 which is supported in turn on the respective corners of a top plate 11, which similarly has a rectangular shape. There is an opening 12 in each of the respective corners of this top plate, in the vicinity of the column elements 8, being so arranged that when required the said column element 8 can be moved through the said opening 12.Four air cylinders 13 are each supported by a fixing 14 which is rigidly connected to the top plate 1 1, these fixings 14 being distributed in pairs on two of the edges 1 A and 11 B respectively of the top plate 11 , which are disposed mutually parallel in pairs. A holdingdown plate 1 5 is supported at the respective corners of the top plate 11 by means of pistons 1 3A which can be moved out of the said cylinders 13.

On the underside of the top plate 11 a punch holder 1 6 is mounted, being rigidly connected to the top plate 11. Two further air cylinders 1 7 are arranged on the machine and are mounted on the stand 2, their piston rods 1 7A extending through both the top plate 11 and the punch holder 16, and able to move out in a downwards direction towards the base plate 3. The free ends of these two piston rods 1 7A have flat pressing components 1 7B, the function of which will be explained later.

The punch holder 1 6 bears around its circumference a single punching blade 1 8 or, as in the present example, a plurality of punching blade parts 1 8A which in the assembled state have the form the punching blade 1 8 needs to have to produce the desired hole shape, such as, for example, an oval cut-out, in the sandwich element 1 during the punching process.The blade 18 or blade parts 1 8A are provided at the top with holes 1 9 which extend right through the blade 1 8 over its full width and each of these holes 1 9 is designed to hold a fixing element, such as a fixing screw 20, for example, by means of which the blade 1 8 is attached to the punch holder 1 6 via holes, preferably tapped, provided at intervals around the circumference of the punch holder 16.

A feed device, which in the example shown is composed of a compressed air cylinder 21 with a piston 21 A which can be moved out and bears a feed element 22, is arranged under the baseplate 3 in the vicinity of the feed path 6, substantially parallel thereto.

A hole 15A, 7A, 3A respectively), the width of which slightly exceeds the circumferential shape formed by the punching blade 18, is provided in the holding-down plate 15, the die 7 and the baseplate 3, the hole 7A in the die 7 having a downwards directed outlet. The blade 1 8 has a substantially straight side 23 and is equipped with teeth 24 which are in the shape of an equiiateral triangle, one apex 24A of which formed the piercing part of the blade point. The straight edge sides 24B of the teeth 24 form an acute angle with the straight side 23 of the blade 1 8 so that a cutting edge 25 is formed at the apex of the angle adjoining the straight side 23.The said straight blade side 23 and the cutting edge 25 formed therefor extend along the whole of the longitudinal extent of the blade 1 8. The longitudinal extent of the desired hole is determined by the position of the said straight side 23 and the cutting edge 25, which in the example showh face away from the centre of the punching blade holder 16. In this case, a smooth surface is obtained on the sheetform layers 1A of the sandwich element when punching a hole out of a workpiece 1, but if the straight side 23 and the cutting edge face instead towards the punching blade holder 16, the surfaces will be smooth on the cut-out part instead, which is advantageous in the case where it is desired to produce such cut-out parts from the sandwich element.

The side 26 of the blade 1 8, which faces away from the said straight side 23, has a shape which deviates from the straight shape in that each side of every tooth 24 is equipped with a preferably curved ridged 27 which extends from the point 24A of the tooth over the height of the tooth 24 for part of the way up the blade 1 8, as shown in Figure 6C.

A process using the apparatus described above for making a hole 28 with rounded corners in a sandwich element 1 intended to be used in a door structure to accommodate a window will now be described in more detail.

The sandwich element 1, which may be in an elongated form which can be cut up into suitable lengths after the holes 28 have been punched out, is supplied to the punching die 7 with the aid of supporting and transporting arrangements which are not shown in the drawing, for example, in the form of running rollers which are arranged at the same height as the level of the said punching die 7. The continuous advance feeding of the element 1 through the punching apparatus is limited appropriately by an abutment stop, the position of which can be adjusted relative to the punch 18, and which may be formed by a movable part which can be pushed along a linear beam and can be locked to the said linear beam.

The lowering of the top plate 11 the punch holder 1 6 and the puch 18 brings about the lowering of the holding-down device 1 5 as well, which means that the workpiece 1 is pressed firmly between the holding down device 1 5 and the punching die 7. As the lowering of the top plate 11 and the punch 18 continues there are controlled with the aid of the column elements 8 which may be provided, at least at their upper end, with devices to improve sliding. As lowering proceeds the piston rods 1 3A are moved in their respective piston cylinders 1 3 and the punch 1 8 is moved in the direction through the workpiece 1 into the position shown in Figure 3.When the punch 1 8 has taken up the said position shown in Figure 3, the air cylinders 17 are appropriately activated so that the piston rods 1 7A and the pressing components 1 7B attached to the free ends thereof push out the part 29 which has been punched out of the workpiece, down through the holes 7A and 3A in the punching die 7 and the baseplate 3 respectively.

Stops, which are not shown on the drawings and which may be arranged between the base plate and the top plate 3 and 11 respectively, limit the closeness of the two plates to each other and also the depth to which the punching blade 1 8 is lowered. It is important that the teeth 24 of the blade pass down through the hole 7A in the punching die 7.

As shown in Figure 4, the part 29 which has been punched out is thereafter removed from the apparatus with the aid of feeding devices 21,21 A, 22 which operate in the cross-wise direction, and is expediently conducted to a store for such parts 29 by means of a conveyor which is not shown in the drawings.

After the punching blade 18, the top plate 11, the holding-down device 1 5 and the pressure elents 1 7 have been raised, the workpiece 1 is free to be moved, either out of the arrangement or to a further punching position which can be set up as before with the aid of an adjustable stop (not shown), after which the punching of a further hole in the element 1 is carried out in the same way as described above.

As stated above, the cut edges on the hole 28 are free from irregularities since the straight side 23 of the blade 1 8 does not deform the cut edges as the blade 1 8 is being passed through the workpiece 1 but cuts through it like a knife edge.

On the other hand, the part of the workpiece 1 on which the non-straight side 26 of the blade acts is deformed along the cut edge.

Claims

1. A process for making a hole through a sandwich element, wherein a punching tool which has a punching blade equipped with pointed teeth and extending along the desired cutting line of the hole, and with a substantially straight side following the desired cut edge and extending in the movement direction of the punching tool relative to the workpiece concered, and with reducing thickness towards the side edges and points of the teeth is passed right through the element.

2. Apparatus for making a hole through a sandwich element comprises a punching tool which has a punching blade equipped with pointed teeth and extending along the desired cutting line of the hole, and with a substantially straight side following the desired cut edge and extending in the movement direction of the punching tool relative to the workpiece concerned, and with reducing thickness towards the side edges and points of the teeth.

3. Apparatus according to claim 2, wherein the blade is supported on a punch holder in which the blade is fixed by means of fixing devices which pass through the said straight side thereof.

4. Apparatus according to claim 3, wherein the blade is made up of a plurality of punching parts.

5. Apparatus according to any one of claims 2 to 4, wherein the points of the teeth have the shape of a substantially equilateral triangle, one apex of which forms the piercing part of the blade point.

6. Apparatus according to any one of claims 2 to 5, wherein the edge sides of the teeth form an acute angle with the straight side of the blade, forming a cutting edge at the apex of the angle, i.e.

adjoining the straight side of the blade.

7. Apparatus according to any one of claims 2 to 6, wherein at least over the height of the teeth, the blade has reducing blade thickness in the direction towards its side edges one side of each tooth being curved to form a ridge extending in the movement direction of the tooth relative to the workpiece.

8. Apparatus according to any one of claims 2 to 7, wherein the blade which is supported by a punch holder supported in turn by a top plate is movable by a Power cylinder, relative to a workpiece supported on a punch base part in a direction through the workpiece.

9. Apparatus according to claim 8, wherein the punch base parts have holes corresponding to the cutting line of the punching blade, these holes being such that a part punched out from the workpiece can be passed through them.

10. Apparatus according to claim 9, wherein a pushing-out device co-acting with the punched out part is provided for assisting passage of the part through the punch base parts.

11. Apparatus according to claim 9 or 10, wherein a removal arrangement is located at the said punch base part, for removing a punched-out part which has been passed through the holes.

12. Apparatus according to any one of claims 8 to 11, wherein the punch holder is moved in a controlled manner over column elements which are supported on the said base part, and a punch holder plate bears on holding-down device which co-acts with the workpiece and which is preferably supported on power cylinders mounted on the said punch holder plate.

1 3. A process for making holes through a sandwich element substantially as described with reference to the drawings.

14. Apparatus for making holes through a sandwich element substantially as described herein with reference to the drawings.