GB2339229A

GB2339229A - Method of manufacturing sealing strips

Info

Publication number: GB2339229A
Application number: GB9814616A
Authority: GB
Inventors: David Strachan Harris; Harold William Edward Pike
Original assignee: Standard Products Co
Current assignee: Standard Products Co
Priority date: 1998-07-06
Filing date: 1998-07-06
Publication date: 2000-01-19
Anticipated expiration: 2018-07-06
Also published as: GB9814616D0; GB2339229B

Description

2339229 METHOD OF MANUFACTURING SEALING STRIPS This invention relates to a

method of manufacturing sealing strips, in particular sealing strips which include a metal reinforcing core. Such sealing strips are employed in the motor vehicle manufacturing industry, where they are used for sealing purposes in the region of windows having reciprocating sheets of glazing material and also in the region of door frames to effect a good seal between the door and the frame.

In such seals there is often an attachment portion which is generally channel-shaped and in which is located the metal reinforcing core, which helps to secure the attachment portion to a flange or like member. The reinforcing core often includes a plurality of generally parallel ribs disposed side by side along the length of the sealing strip.

During the manufacture of such a sealing strip it is well known to take a metal strip, to cut or lance it so as to provide a series of uniform slits and, at a suitable stage during the multi-stage manufacturing process, to stretch the slit strip so that the slits widen into slots. At an appropriate stage the metal strip is passed through an extrusion head and is surrounded by a rubber'or plastics material so that in the resulting product the metal reinforcing core is embedded in the rubber or plastics extrudate. A sealing strip of a considerable length, equivalent to the length of the initial metallic strip, results. The long strip then needs to be cut into lengths of a predetermined magnitude for use on an appropriate part of a motor vehicle. Por instance, if the sealing strip is to be used to seal the region between the periphery of a door and the door frame, the sealing strip may need to have a length of, say, four metres.

With the metal strip being fed into the processing plant at the upstream end, it is important that any cutting equipment, necessary for cutting the resulting sealing strip to the appropriate length, knows where to cut the strip. For this purpose a sensor can be employed to endeavour to ensure that the cutting blade or blades act in the region of a slot formed between two ribs, in order to minimise the amount of metal which needs to be cut and in order therefore to minimise the amount of metal potentially exposed at the resulting end of the cut length. For a door frame the cut length of four metres (or whatever length is required) is suitably shaped and the two end regions secured to each other to form a gasket, for example by a known technique.

In practice, bearing in mind that the sealing strip formed of the extrudate with a metal core embedded therein, and possibly already formed into a channel shape, is moving, it can be difficult for the cutting system, which is to cut the sealing strip into lengths of the predetermined magnitude, to act solely in the region of a metal bridge between adjacent ribs, in other words for the cutting blade or blades to move through the slot between an adjacent pair of ribs. It is difficult for any sensing equipment to sense the slot accurately and also for the blade or blades to enter the slot or slots accurately.

According to a first aspect of the present invention, there is provided a method of manufacturing a sealing strip formed of an extruded rubber or plastics material in which is embedded a metal reinforcing core, uhich method comprises:

providing an elongate metal strip; providing slits in the strip, with ribs being defined by metallic material between adjacent pairs of S14 tS slits and with the -L. optionally extending to the edge of the metallic strip; extruding extrudable rubber or plastics material around the strip; stretching the metal strip and any extruded material already around the strip, so that the slits in the strip become slots; and then cutting the stretched strip into lengths of the desired magnitude; characterised in that:

prior to extrusion, gaps larger than the usual spacing between an adjacent pair of ribs are created, the gaps being at predetermined intervals along the length of the strip, corresponding to the length of desired magnitude, wherein the gaps are created by (i) folding back edge regions of the ribs on opposite sides of a slit, (ii) forcing adjacent ribs apart by forcing a wedge into the slit between the adjacent ribs, or (iii) flexing a rib in alternate directions so as to cause it to snap off.

By having a gap which is larger than the usual spacing between adjacent ribs in a pair of ribs, it is possible for a sensor to recognise more easily where the cut is to take place and it is also possible for the blade or blades used to cut the sealing strip into the predetermined lengths to act merely on any relatively small metal bridge extending longitudinally between one rib of the reinforcing core and its neighbour.

In practice, on the production line, there will be additional pieces of equipment present. Thus the equipment for providing the gaps might be immediately downstream of the "accumulator" used for feeding a continuous strip of metal core material, which might already be pre-cut or pre-lanced so as to provide the slits. Such material is then fed into the equipment which provides the gaps. The resulting metal strip provided at predetermined intervals with the gaps then passes into a roll former so as to cause the planar strip to be formed into a channel of the desired shape, after which the shaped strip is fed into the extrusion head in which it is surrounded by the appropriate flexible extrudate. The material emerging from the extrusion head passes through ovens and a cooler and is drawn off by a "haul-off"roller system before being passed to the cutter which is to cut through the strip in the predetermined points in the region of the gaps, the "haul-off" equipment causing the strip to be stretched in the roll former and extrusion head.

Sensors can be provided in the region of the gap forming component, in the region between the extrusion head and the first oven, and in the region of the cutter used to cut the shaped sealing strip into lengths of determined magnitude, and there can be control means for supplying feedback relating to the amount of stretch present in, or required in, the roll former and extrusion head, and there can also be provision for feedback for the correction of the amount of stretch in the process between the sensor in the region of the cutter and the sensor in the region of the gap-forming component.

One advantage of the present invention is that starting metallic core material can be provided with slits already in situ from a metal supplier, and such strips can then, without any further processing, be fed straight into the accumulator at the upstream end of the plant used to carry out the method of the present invention. Long rolls/reels of such slit reinforcing core material (as obtained from an external supplier) are joined end to end in the accumulator and fed downstream where the first treatment is the provision of the gaps by the wedge-driven equipment, or by the folding equipment (which folds back edge regions of the ribs adjacent a slit), or by the working of spaced- apart ribs so as to break them off. It is to be appreciated that no additional cutting is required at this stage, which simplifies the provision of the gaps which are to be sensed further downstream.

According to a second aspect of the present invention, there is provided a method of manufacturing a sealing strip formed of an extruded rubber or plastics material in which is embedded a metal reinforcing core, which method comprises:

providing an elongate metal strip; providing slits in the strip, with ribs being defined by metallic material between adjacent pairs of slits and with the slits optionally extending to the edge of the metallic strip; extruding extrudable rubber or plastics material around the strip; stretching the metal strip and any extruded material already around the strip, so that the slits in the strip become slots; and then cutting the stretched strip into 'Lengths of the desired magnitude; characterised in that:

prior to extrusion, large gaps are created in the strip by the removal of the two or more adjacent ribs, by flexing the ribs so as to cause them to snap off.

The large gaps can be identical on opposite sides of the strip, or gaps on one side of the strip can be offset with respect to, and/or of different lengths with respect to, the gaps on the other side of the strip.

The second aspect of the present invention can be combined with the first aspect of the present invention, to provide, in addition to the smaller gaps for easing sensing and cutting of the strip into lenaths of the desired magnitude, la-rger gaps whose requireme purpose is related to the nts of the seal at S 4 different locations. Thi Ls a third aspect of the present invention.

According to a fourth aspect of the present invention, there is provided a machine for causing one or more than one rib of a core having ribs on either side of a spine to be flexed and, after weakening, to be snapped off, the machine comprising:

guide means for guiding the core in a direction corresponding to its major dimension; a tool plate capable of being reciprocated, with opposing parts of the tool plate being capable of striking opposite sides of the one or more than one rib; support means for supporting the tool plate and for allowing it to undergo reciprocal movement; and driving means capable of causing the tool plate to undergo reciprocal movement.

The tool plate may be so shaped that, when moving in one direction, it strikes one face of a pair of ribs on opposite sides of the spine but, when moving in the opposite direction, it strikes the opposite face of that pair of ribs.

The shape of the plate, or its line of action, may be altered such that it hits the opposing faces of only one rib.

Alternatively, the thickness of the tool plate may be increased so that, instead of striking the opposite faces of only one rib or one pair of ribs on opposite sides of the spine, the plate strikes the opposite faces of two or more adjacent ribs on one side of the spine, or the opposite faces of two or more adjacent ribs on one side of the spine and two or more adjacent ribs on the other side of the spine.

If desired, the equipment for carrying out the method of the first aspect or the second aspect of the present invention may include one or more than one machine in accordance with the fourth aspect of the present invention. Where two or more such machines are present, they may be accurately controlled by suitable control apparatus so as to act in a synchronised manner such that the desired ribs are flexed and broken off as the core advances. In fact, the equipment makes it possible to remove individual ribs on one side of a centreline or the opposite side of a centreline or each side of a centreline in singles, pairs, multiples or combinations thereof, at precise or variable preset intervals, at the touch of a button.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, is to the accompanying drawings, in which:

Figure 1 is a plan view of a first embodiment, in flat form, of a reinforcing core formed by the method of the present invention; Figure 2 is a plan view of a second embodiment, in flat form, of a reinforcing core formed by the method of the present invention; Figure 3 is a plan view of a third embodiment, in flat form, of a reinforcing core formed by the method of the present invention; Figure 4 is a plan view of the fourth embodiment, in flat form, of a reinforcing core formed in accordance with the method of the present invention; Figure 5 is a plan view of a fifth embodiment, in flat form, of a reinforcing core formed in accordance with the present invention; Figure 6 is a diagrammatic scheme showing the components of apparatus used for producing sealing strips in accordance with the method of the present invention; Figure 7 is partly a side elevation and partly a vertical section of a machine for breaking off ribs of a reinforcing core in accordance with the present invention; Figure 8 is partly a front elevation and partly a vertical section of the machine of Figure 7; and Figure 9 is a plan view of the machine of Figure 7.

Referring firstly to Figure 1, there is shown a reinforcing core 1 which has a spine 2 and, projecting on one side of the spine 2, a series of ribs 3A, 3B, 3C, 3D, 3E, 3F, 3G etc., and projecting on the other side of the spine 2, a series of ribs 4A, 4P, 4C, 4D, 4E, 4F, 4G, opposite the correspondingly numbered ribs 3A to 3G, respectively. There are small slits between adjacent ribs, such as the ribs 3A and 3B.

A gap 5 is formed between the ribs 3E and 3F by folding back adjacent regions of those ribs 3E and 3F, and a corresponding gap 6 is formed on the opposite side between the ribs 4E and 4F by the adjacent regions of those ribs being folded back. Thus the gaps are created by the first, (i), of the three possible techniques mentioned in the first aspect of the present invention. When the core is formed into the right shape and incorporated into the seal by having extrudable rubber or plastics material extruded around it and then with the strip being stretched, a sealing strip is formed which has a reasonably large gaps 5, 6, which can relatively easily be detected by a sensor and suitable cutting action applied to the gaps so as to sever one length of sealing strip from an adjacent length.

Turning now to Figure 2, much of what is shown in Figure 2 is similar to w',--at is shown in Figure 1 and, generally speaking, the components numbered 11 to 16 in Figure 2 correspond to the components numbered 1 to 6, respectively, in Figure 1. The significant difference, however, is that the gaps 15 and 16, instead of being created by opposing adjacent edge regions of neighbouring ribs being folded back, are created by wedges being driven into the slits between adjacent ribs. Thus a first wedge is driven between ribs 13E and 13F and a second wedge is driven between ribs 14E and 14F, to create the gaps 15 and 16, respectively.

Turning now to Figure 3, the components shown in the core of Figure 3 are in many respects similar to those shown in Figures 1 and 2 and, generally speaking, the components numbered 21 to 26 in Figure 3 correspond to the components numbered 1 to 6, respectively, in Figure 1 except for the manner in which the gaps 25 and 26 in Figure 3 are created. In the Figure 3 arrangement the gaps are created by the free end regions of the ribs 23H and 24H being flexed, usually over a small distance at high speed, until the free end regions snap off, just leaving stubs or residual ribs as shown in Figure 3, thereby creating the gaps 25 and 26.

The arrangements shown in Figures 4 and 5 are more concerned with the second aspect of the present invention, which involves the creation, prior to extrusion, of large gaps by the removal of two or more adjacent ribs by flexing.

In fact, in the arrangement shown in Figure 4, which shows a core 41 having a spine 42 with ribs 43 projecting on one side and ribs 44 projecting on the opposite side, the free end region of two opposing ribs are broken off so as to form residues 43N and 44N, respectively, just like the ribs 23H and 24H in Figure 3. Additionally, however, the free end regions of 10 ribs adjacent rib 44N are also subjected to the flexing action with the result that they are weakened and removed, these being the ribs indicated as 44P. The purpose of providing a large gap of this nature is to enable the final sealing strip which Jincorporates the reinforcing core to be accommodated satisfactorily within the automobile body.

With regard to the arrangement shown in Figure 5, here again there is a reinforcing core 51 having a spine 52 with ribs 53 projecting from one side and ribs 54 projecting from the other side. In one region, five ribs 53N are weakened at their free end regions and broken off to provide mere stubs and, opposite that, five ribs 54N are also broken off so that a large gap of equal dimension appears opposite to the large gap on the one side.

Further along the reinforcing core another five ribs are weakened and removed, but on one side only, these being the ribs 53P.

is No ribs directly opposite those ribs 53P are removed. However, on the opposite side but yet further along, nine ribs are flexed, weakened and broken off to form another, larger gap, these being indicated by the residual ribs 54Q.

Figure 6 shows schematically an apparatus for carrying out a method in accordance with one or other aspect of the present invention. In this apparatus there is shown an accumulator containing a reel of reinforcing core having a spine and, on either side thereof, opposing ribs, with small slits between the ribs. The core material is passed from the accumulator G1 to the notcher 62 where notches are provided, in accordance with the first mentioned aspect of the present invention or in accordance with a second mentioned aspect of the present invention. The notches are provided in order to assist in the sensor determining where the long strip of reinforcing core is to be cut, and also to facilitate the cutting itself.

The notched reinforcing core passes from the notcher 62 to a roll former 63 where the core is gently bent into a channel-sha,,Ded configuration, and from there it moves to the extruder head 64 to which polymer is added from extruder(s) 64A, there emerging from the extruder head 64 the extruded sealing strip, in which the core has been stretched during the forming and extrusion exercise. A sensor, 72, senses the degree of stretching in the resulting seal, so as, if appropriate, to enable the magnitude of stretching to be corrected, through a feedback in line 73. The extruded sealing strip passes into oven 65 to cure the rubber or plastics material and then into-a cooler 66.

The strip is pulled through the whole line by the haul off rollers 67 and then passed to a cutter 68 which acts in conjunction with the notch sensor 69 so as to ensure that the cutters cut where the gap is located, the sensor 69 sending a signal back through the line 70 to the sensor 71 near the notcher so that any need for correction of stretch in the process can be determined and adjustments made.

Turning now to the machine illustrated in Figures 7/ 8 and 9, the machine is one capable of vibrating the free end regions of ribs of a reinforcing core so as to weaken those free end regions, thereby causing their removal so as to create gaps, such gaps either being equivalent to a single rib to assist detection by the sensor and cutting by the cutter or being larger gaps to assist in the fitting of the sealing strip to the automobile body.

The machine 80 includes a mounting plate 81 on which stand two columns 82 and 83 which are spaced apart and which are capped by a head plate 84 secured to both columns 82 and 83.

Also standing on the mounting plate 81 are two posts 85 and 86 which are disposed on opposite sides of the plane in which the columns 82 and 83 lie. The posts 85 and 86 are only about half the height of the columns 82 and 83. Mounted on the rcszs 85 and 86, and passing through the gap between the columns 82 and 83, is a guide 87 with an integral anvil 88. The guide 87 serves to carry the reinforcing core, in flat form, as it passes through the notching station in the region of the anvil 88. That face of the column 82 which faces the column 83 is provided with a groove 89, and similarly that face of the column 83 which faces the column 82 is provided with a groove 90. Positioned between the two column 82 and 83 is a reciprocating tool plate 91 which has opposing edge regions 92 and 93 located in the grooves 89 and 90, respectively. The reciprocating tool plate 91 lies in a vertical plane which is perpendicular to the length of the spine of a reinforcing core being fed through the guide 87.

is The lower end region of the tool plate 91 is secured to a rod 94 which is joined by a pivotal connection 95 to one end of a connecting rod 96 which, at its opposite end, is joined by a pivotal connection 97 to a cam plate 98 capable of being rotated about its central axis 99 by means of a motor 100. The motor 100 is secured to the underside of the mounting plate 81.

it can be appreciated that rotation of the motor 100 causes rotation of the cam plate 98 with consequent upward and downward movement of the connecting rod 96 and of the rod 94, with resultant upward and downward movement of the tool plate 91. The upper edge region of the tool plate 91 is secured to a rod 101 capable of undergoing reciprocating movement within a spring guide/bush 102 located in the centre of the head plate 84.

when it is desired to create gaps, such as the gaps 25 and 26 shown in Figure 3, in the flat-form reinforcing core, the motor 100 is activated and suitably shaped internal edge regions 103 strike opposing ribs with a considerable force at a high frequency, thereby causing the ribs to be broken off.

In the arrangement shown in Figures 7, 8 and 9, the tool plate 91 is of such a nature that it acts on two opposing ribs in the reinforcing core so as to create two opposing gaps, like the gaps 25 and 26 shown in Figure 3.

If, however, only one rib is to be vibrated, weakened and removed, such work could be undertaken at a separate work station with a similar machine but in which the tool plate has different characteristics so that only one rib is removed. Similarly, where a plurality of adjacent ribs is to be removed, such as at 53P in Figure 5, the reciprocating tool plate can be thicker and can act on numerous adjacent ribs, rather than merely one rib, so as to produce the desired result. To achieve this, it may be necessary to have numerous different work stations each having its own reciprocating tool plate, but the plates having different characteristics depending on the desired results. obviously the action of the different work stations needs to be coordinated so as to ensure that the resulting reinforcing core has the ribs removed in the correct regions.

Claims

1. A method of manufacturing a sealing strip formed of an extruded rubber or plastics material in which is embedded a metal reinforcing core, which method comprises:

providing an elongate metal strip; providing slits in the strip, with ribs being defined by metallic material between adjacent pairs of slits and with the slits optionally extending to the edge of the metallic strip; extruding extrudable rubber or plastics material around the strip; stretching the metal strip and any extruded material already around the strip, so that the slits in the strip become slots; and then cutting the stretcheestrip into lengths of the desired magnitude; characterised in that:

2. A method according to claim 1, which also includes feeding a continuous strip of metal core material, which is already pre-cut or pre-lanced so as to provide the slits; and, after the metal strip has been provided at predetermined intervals with the gaps, passing the strip into a roll former so as to cause the planar strip to be formed into a channel of the desired shape, after which the s'I-Laped strip is -Eed inzo the extrusion head in which it is surrounded by the appropriate flexible extrudate.

3. A method according to claim 2, wherein the material emerging from the extrusion head passes through ovens and a cooler and is drawn off by a "haul off" roller system before being passed to a cutter which is to cut through the strip in the predetermined points in the region of the gaps, the "haul-off" equipment causing the strip to be stretched in the roll former and extrusion head.

4. A method according to claim 4, which includes sensing in the region of the gap-forming component, in the region between the extrusion head and the first oven, and in the region of the cutter used to cut the shaped sealing strip into lengths of determined magnitude, and providing control means for supplying feedback relating to the amount of stretch present in, or required in, the roll former and extrusion head, and there can also be provision for feedback for the correction of the amount of stretch in the process between the sensor in the region of the cutter and the sensor in the region of the gap-forming component.

5. A method of manufacturing a sealing strip formed of an extruded rubber or plastics material in which is embedded a metal reinforcing core, which method comprises:

providing an elongate metal strip; providing slits in the strip, with ribs being defined by metallic material between adjacent pairs of slits and with the slits optionally extending to the edge of the metallic strip; extruding extrudable rubber or plastics material around the strip; stretching the metal strip and any extruded material already around the s-Lri,,D, so that the slits in the strip become slots; and then cutting the stretched strip into lengths of the desired magnitude; characterised in that:

6. A method according to claim 5, when combined with the method of any one of claims 1 to 4, so as to provide, in addition to the smaller gaps for easing sensing and cutting of the strip into lengths of the desired magnitude, larger gaps whose purpose is related to the requirements of the seal at different locations.

7. A machine for causing one or more than one rib of a core having ribs on either side of a spine to be flexed and, after weakening, to be snapped off, the machine comprising:

8. A machine according to claim 7, wherein the tool plate is so shaped that, when moving in one direction, it strikes one face of a pair of ribs on opposite sides of the spine but, when moving in the opposite direction, it strikes the opposlite face of that pair of ribs; and wherein the shape of the plate, or its line of action, may be altered such that it hits the opposing faces of only one rib.

9. A machine according to claim 7, wherein the thickness of the tool plate may be increased so that, instead of striking the opposite faces of only one rib or one pair of ribs on opposite sides of the spine, the plate strikes the opposite faces of two or more adjacent ribs on one side of the spine, or the opposite faces of two or more adjacent ribs on one side of the spine and two or more adjacent ribs on the other side of the spine.

10. Equipment for carrying out the method of claim 1 or the method of claim 5, which includes one or more than one machine in accordance with any one or more of claims 7 to 9.

11. Equipment according to claim 10, wherein when two or more machines are present, there is also present suitable control apparatus so as to cause the machines to act in a synchronised manner such that the desired ribs are flexed and broken off as the core advances.

12. A machine according to claim 7, substantially as hereinbefore described with reference to, and as illustrated in, Figures 7 to 9 of the accompanying drawings.