GB1592647A

GB1592647A - Joining strip material

Info

Publication number: GB1592647A
Application number: GB5096976A
Authority: GB
Original assignee: Lockwood A W
Current assignee: Lockwood A W
Priority date: 1977-12-07
Filing date: 1977-12-07
Publication date: 1981-07-08

Description

(54) JOINING STRIP MATERIAL (71) I, ARTHUR WILLIAM LOCKWOOD, a British subject, of The Hoe, Toweridge Lane, Upper Sands, High Wycombe, Buckinghamshire, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method of joining strip material.

The invention is particularly concerned with joining two ends of a single strip so as to form an endless conveyor belt and is more particularly concerned with the type of conveyor belt used in the clothing industry for conveying textiles into and/or through apparatus for bonding one or more layers of textile material together. Such apparatus is, for example, described in British Patent Specification No. 1,335,417.

Conveyor belts of this type are subjected to high temperatures and are typically made from woven glass fibre covered with polytetrafluoroethylene. They are, therefore, expensive and care must be taken to ensure that their working life is not unnecessarily reduced. One particular problem that arises in this respect is the formation of a strong joint between the ends of the continuous strip.

Belts of this type cannot be joined by metal joints which are often used in conveyor belts, because the belt has to pass through pressure rollers and a metal joint would not only be too thick to pass readily between the rollers, but would also be liable to damage them.

It has been proposed to join the ends of belts by forming an overlap and either applying adhesive to the overlap or fusing the overlapped portions so as to make the bond. It has also been proposed to join the ends of belts by a simple butt joint with a strip of material fused or adhered to the underside of the belt to provide re-inforcement. The strength of both these joints is solely dependent on the bond strength and furthermore a small tear on one side of the joint may propagate across the width of the web. In addition, the narrow overlap area can lead to the formation of pressure imprints on the textile materials. The problems can be reduced, but not completely eliminated, by forming the joint at an angle, typically at 60 to the longitudinal axis, but even so other problems arise.For example, a butt joint suffers from a tendency to open up when the belt is pulled around small rollers and this may further lead to the collection of dust within the joint with resultant soiling of the textile materials.

In another proposed method the glass fibre strands of two belt ends are interwoven and bonded.

Although this method produces a substantially flush joint and thus eliminates the problem of pressure imprints, the necessary removal of yarn considerably weakens the belt and the area of the joint must be kept as small as possible. This limits the bond strength of the joint and the slightest tear at an edge quickly results in a complete break.

Because of the method of construction, it is impossible to form the joint at an angle to reduce the danger of tear propagation. An additional problem also arises with this type ofjoint in that the polytetrafluoroethylene on either side of the joint tends to break away, leaving uncovered interwoven glass fibre strands.

The present invention is based on my observation that a conveyor belt may be formed from one or more parts of strip material by forming slits in each end portion of the part(s) concerned so that a pair of end portions can be brought into aligned interlocking engagement to produce a joint which, although it has a broken join line across the width of the belts, has a constant thickness across said width, because the slits are formed without cutting away or otherwise removing any part of the belt.

More especially my invention provides a method of forming a joint between the end portions of one or two parts of a conveyor belt which comprises (a) providing both end portions with slits so that the portions can be brought into aligned interlocking engagement (as hereinafter defined), each of said slits having an origin within its end portion and at least one of said slits having an open end, the position of the slits being such that when the end portions are brought into aligned interlocking engagement the origins of the slits of one end portion coincide with the origins of the slits of the other end portion, there being at least two such origins in each end portion, and (b) bringing said end portions into aligned interlocking engagement to form the joint.

The present invention further provides a conveyor belt made by forming one or more joints in accordance with the above method as well as apparatus comprising such a conveyor belt. The present invention also provides a part (or parts) of strip material having end portions provided with slits and adapted to form a joint in accordance with the method defined above.

By "interlocking engagement" there is herein meant that when the end portions of the strip material are aligned and engaged so that their origins coincide, they cannot be separated simply by moving them apart along the longitudinal axis of the strip material.

A joint according to the invention can be formed with an equal thickness of belt material across the whole width of the belt on both sides of the joint. This protects the belt from buckling caused by differential heating and cooling rates.

The joint may be formed across the width of the web, that is in a direction normal to the longitudinal axis, but is advantageously formed at an angle other than 90 , for example at an angle greater than 30 , to said axis preferably between 45" and 75 and, more especially, about 60 .

In preferred embodiments, the slits are so positioned that no part of them lies in a longitudinal axis of the belt(s). Thus, when, as preferred, the joint is formed at an angle to the longitudinal axis of the belt, the arms of the slits preferably lie parallel or perpendicular to this line of the joint.

For convenience, two slits whose origins are superimposed when the end portions are in aligned interlocking engagement will, from hereon, be referred to as a "pair of slits'.

It will, however, be appreciated that where, as described hereinafter, one slit has two origins within its end portion it can form two "pair of slits' with two independent slits in the other end portions.

It is advantageous that one slit of a pair should extend from its internal origin in a substantially opposite direction to that of the second slit (as viewed when the end portions are in an aligned position), so as to provide optimum engagement between the end portions.

It will be appreciated that in order to interlock the two end portions, it is necessary that at least one slit of a pair, and preferably both, should have an open end, i.e. it should extend to a front or side edge of its end portion.

In order to provide the maximum benefit from the interlocking engagement of the two end portions, it is desirable that the origins are regularly disposed along the joint, that is to say, the distance (along the line of the joint) betweeen origins should preferably be equal.

Furthermore, in order to maximise the interlocking strength of the joint it is desirable to provide the joint with as many superimposed origins as possible, consistent with convenience and the strength of the material of the belt.

In practice pairs of slits are brought into engagement so as to form an interlocking joint between the two end portions and the resulting loose, overlapping parts may be fixed to the rest of the belt by adhesive or by fusion and/or by stitching across the width of the belt.

There will now be described, by way of example, five types of joint according to the invention, with reference to the drawings accompanying the Provisional Specification, in which: Figure 1 shows the two end portions of a belt before a straight, interlocking joint is made; Figure 2 shows the underside of the straight joint made by interlocking the slits in the end portions shown in Figure 1; Figure 3 shows the two end portions of a belt before an angled, interlocking joint is made; Figure 4 shows the underside of the angled joint made by interlocking the slits in the end portions shown in Figure 3; Figure 5 shows the two end portions of a belt before another type of angled interlocking joint is made; Figure 6 shows the underside of the angled joint made by interlocking the slits in the end portions shown in Figure 5; ; Figure 7 shows the two end portions of a belt before a straight interlocking joint is made; Figure 8 shows the underside of the straight joint made by interlocking the slits in the portions shown in Figure 7; Figure 9 shows the two end portions of a belt before an angled interlocking joint is made; and Figure 10 shows the underside of the angled joint made by interlocking the slits in the end portions shown in Figure 9.

Figures 1, 3, 5, 7 and 9 show the two end portions of a belt which are to be joined together.

For clarity, one end portion is shown with dotted lines. It will be appreciated, however, that all slits and edges are continuous.

Referring to Figures 1, 3 and 5, two pairs of slits (1 and 1', 2 and 2') are formed in the belt, one of each pair being in each end portion. The origins of the slits of each pair (3 and 3', 4 and 4') lie at the same distance from the edge of the belt. Slits 1 and 2 are brought into interlocking engagement with slits 1' and 2', respectively, so that their origins 3, 3' and 4, 4', respectively, coincide giving the joints shown in Figures 2, 4 and 6.

Figures 7 and 9 show two end portions of a belt one end portion has one slit 7, formed therein and the other has two slits 8 and 9.

The slit 7 has two origins (10 and 11) and slits 8 and 9 each have one origin (10' and 11') within the belt. Slits 8 and 9 are brought into interlocking engagement with slit 7 so that their origins 10, 10' and 11, 11', respectively, coincide so as to give joints as shown in Figures 8 and 10.

When the end portions are interlocked the overlapping portions may be bonded together by a suitable adhesive or by fusion.

[Thus flaps 5 are bonded to the rest of the belt.] All the joints shown in Figures 2, 4, 6, 8 and 10 are interlocking and therefore their strength is not wholly dependent on the strength of the bond between the flaps 5 and the belt but depends also on the engagement of the belts in the vicinity of the superimposed origins of the slits. The joints have a uniform thickness on either side of the joint thereby preventing buckling due to differential heating and cooling effects. It will be appreciated that a conveyor belt which has a joint as shown in Figures 2, 4, 6, 8 or 10 can be fitted in a conveyor line which moves in either direction.

The joints shown in Figures 4, 6 and 10 are advantageous in that there is a less defined overlap area thereby facilitating their passage between pressure rollers. These angled joints are also less liable to tear from side to side than straight joints.

The angled joint shown in Figure 6 is particularly advantageous in that it possesses no line which is parallel to the movement of the conveyor belt. When the joint is stretched along the longitudinal axis of the belt flaps 5a and 5 b engage at intersection 6 giving added strength to the joint. This feature is not present in the joints shown in Figures 2 and 4 since the ends of the slits 2 and 1' remote from their respective origins lie parallel to the longitudinal axis of the belt.

Although the present invention has been described in connection with joining two ends of a particular type of conveyor belt to form a continuous closed loop it will be appreciated that it is possible to join two independent strips of belt material in this manner.

Furthermore, the invention has application in joining many types of conveyor belt material, not only the type used in textile pressing machines.

WHAT I CLAIM IS: 1. A method of forming a joint between two end portions of strip material which comprises (a) providing both end portions with slits so that the portions can be brought into aligned interlocking engagement (as hereinbefore defined), each of said slits having an origin within its end portion, and at least one of said slits having an open end, the position of the slits being such that, when the end portions are brought into aligned interlocking engagement, the origins of the slits of one end portion coincide with the origins of the slits of the other end portion, there being at least two origins in each end portion, and (b) bringing said end portions into aligned interlocking engagement to form the joint.

2. A method as claimed in claim 1, wherein the strip material is material suitable for use in a conveyor belt.

3. A method as claimed in claim 1 or claim 2, wherein there is an equal thickness of material on either side of the line of the joint.

4. A method as claimed in any one of claims 1 to 3, wherein the line of the joint is formed at an angle other than 90 to the longitudinal axis of the strip material.

5. A method as claimed in any one of claims 1 to 4, wherein the line of the joint is formed at an angle greater than 30 to the longitudinal axis of the strip material.

6. A method as claimed in claim 4 or claim 5, wherein said angle is in the range of from 45 to 75 .

7. A method as claimed in claim 6, wherein said angle is 60 .

8. A method as claimed in any one of claims 1 to 7, wherein each slit is made up of one or more parts, and the or each part extends in a direction which is either parallel or perpendicular to the line of the joint.

9. A method as claimed in any one of claims 1 to 8, wherein one slit of a pair of slits (as hereinbefore defined) extends from its origin in a direction which is substantially opposite to the direction in which the other slit of the pair extends from its origin.

10. A method as claimed in any one of claims I to 9, wherein the origins of the slits in each end portion are regularly disposed along the line of the joint.

Il. A method as claimed in any one of claims I to 10, wherein the loose overlapping parts of the strip material which result from the formation of the joint are fixed to the rest of the strip material by adhesive, or by fusion and/or stitching across the width of the strip material.

12. A method as claimed in any one of claims 1 to 11, wherein the two end portions are end portions of the same piece of strip material.

13. A method as claimed in claim 1,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. portion. The origins of the slits of each pair (3 and 3', 4 and 4') lie at the same distance from the edge of the belt. Slits 1 and 2 are brought into interlocking engagement with slits 1' and 2', respectively, so that their origins 3, 3' and 4, 4', respectively, coincide giving the joints shown in Figures 2, 4 and 6. Figures 7 and 9 show two end portions of a belt one end portion has one slit 7, formed therein and the other has two slits 8 and 9. The slit 7 has two origins (10 and 11) and slits 8 and 9 each have one origin (10' and 11') within the belt. Slits 8 and 9 are brought into interlocking engagement with slit 7 so that their origins 10, 10' and 11, 11', respectively, coincide so as to give joints as shown in Figures 8 and 10. When the end portions are interlocked the overlapping portions may be bonded together by a suitable adhesive or by fusion. [Thus flaps 5 are bonded to the rest of the belt.] All the joints shown in Figures 2, 4, 6, 8 and 10 are interlocking and therefore their strength is not wholly dependent on the strength of the bond between the flaps 5 and the belt but depends also on the engagement of the belts in the vicinity of the superimposed origins of the slits. The joints have a uniform thickness on either side of the joint thereby preventing buckling due to differential heating and cooling effects. It will be appreciated that a conveyor belt which has a joint as shown in Figures 2, 4, 6, 8 or 10 can be fitted in a conveyor line which moves in either direction. The joints shown in Figures 4, 6 and 10 are advantageous in that there is a less defined overlap area thereby facilitating their passage between pressure rollers. These angled joints are also less liable to tear from side to side than straight joints. The angled joint shown in Figure 6 is particularly advantageous in that it possesses no line which is parallel to the movement of the conveyor belt. When the joint is stretched along the longitudinal axis of the belt flaps 5a and 5 b engage at intersection 6 giving added strength to the joint. This feature is not present in the joints shown in Figures 2 and 4 since the ends of the slits 2 and 1' remote from their respective origins lie parallel to the longitudinal axis of the belt. Although the present invention has been described in connection with joining two ends of a particular type of conveyor belt to form a continuous closed loop it will be appreciated that it is possible to join two independent strips of belt material in this manner. Furthermore, the invention has application in joining many types of conveyor belt material, not only the type used in textile pressing machines. WHAT I CLAIM IS:

1. A method of forming a joint between two end portions of strip material which comprises (a) providing both end portions with slits so that the portions can be brought into aligned interlocking engagement (as hereinbefore defined), each of said slits having an origin within its end portion, and at least one of said slits having an open end, the position of the slits being such that, when the end portions are brought into aligned interlocking engagement, the origins of the slits of one end portion coincide with the origins of the slits of the other end portion, there being at least two origins in each end portion, and (b) bringing said end portions into aligned interlocking engagement to form the joint.

7. A method as claimed in claim 6, wherein said angle is 60 .

13. A method as claimed in claim 1,

substantially as herein before described in connection with Figures I and 2, Figures 3 and 4, Figures 5 and 6, or Figures 7 and 8 of the drawings accompanying the provisional specification.

14. Strip material which contains one or more joints made by a method as claimed in any one of claims I to 13.