US 3335986 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Aug. 15, 1967 H. M. CROSS 3,335,986
HAND LACED SEAMS Filed Sept. 1, 1965 2 Sheets-Sheet 1 /NVENTOR //./1. (Moss ysrm Aug. 15, 1967 M. cRoss HAND LAGED SEAMS 2 Sheets-Sheet 2 Filed Sept. 1, 1965 C H H H H H H H H H H m 11 I H H H A? /NVENTOR h. M. (Russ ATTORNEyS United States Patent 3,335,986 HAND LACE!) SEAMS Harold M. Cross, Valois, Quebec, Canada, assignor to Fabric Research Laboratories, Dedham, Mass. Filed Sept. 1, 1965, Ser. No. 484,395 13 Claims. (Cl. 245) ABSTRACT OF TIE DISCLOSURE A hand laced seam for Fourdrinier wire belts for use in paper making machines whereby the woven seam is flat and virtually invisible and the weave pattern is maintained across the full width of the seam.
This invention relates to hand laced seams in coarse woven cloth and in particular to hand laced seams for Fourdrinier belts.
In the manufacture of Fourdrinier wire belts, it is common to make seams in coarse metallic cable cloth by the woven seam method. In this method, shute wires (weft) are removed from the ends of the cloth and the warps folded back. A number of new shute strands are set up across the cloth in place of the removed strands and threaded through a reed and heddles. The warp ends are then woven into the new strands which replace the removed strands. This results in a bulky seam which is adequate for making pulp sheets, but which is not satisfactory for making lighter grades of paper.
A similar process is disclosed in Canadian Patent No. 707,487 issued Apr. 13, 1965, to Karl U. Schuster. This process leaves a non-marking seam, but it is dependent upon having crimped warp strands, and is limited as to the size of the seam which can be made, thus resulting in relatively poor strength.
The method of manufacturing woven endless textile belts by seaming them into an endless loop by the hand lacing technique is old in the art, and is used for example in paper machine wet press felts. In this application loosely woven woolen or synthetic fabrics are joined to form anendless belt. These felts are then fulled, a process wherein the fabric is washed vigourously and which results in a severe shrinkage and entanglement of the textile fibres with one another in the region of the hand laced seam. This process makes the seam virtually of the same character as the body of the felt. Thus in the old art the method is applied to loosely woven fibres: strength is obtained by using a Very large sized seam and by the subsequent fulling process.
The present invention consists essentially in a method by which a Fourdrinier fabric, or a similar type of fabric for other uses, can be woven flat on a conventional loom to the desired width and length, and then seamed by hand so as to form endless belts. The hand laced seam is virtually invisible and maintains the wave pattern across the joint. There is no over-lapping of strands and hence no drainage obstruction.
The fabric woven in a conventional flat loom is cut to a length longer that the required length, than seamed with a temporary seam, such as a sewn seam, into an endless loop. The formed loop is then applied to a heatsetting frame and the fabric is heat set by simultaneously applying heat and tension to the fabric. In this process the machine direction strands (circumferential strands), which in this case are the warp strands, are straightened and the fabric is lengthened permanently. Prior to this step the warp strands are crimped and their movement through the fabric in their own direction is inhibited by the crimp. The temporary seam is then cut-out and the heat set fabric is cut to the required length plus about 12 inches. Weft strands are removed equally on the opposing edges of the fabric to be joined, until the length of fabric containing undisturbed weft strands is equal to the desired loop length, exposing warp ends approximately six inches long. The two opposing ends of the fabric are brought together on a fiat table or frame so that the first remaining weft strand at each end are in normal weave spacing relationship to each other. The brought together warp ends are interdigitated with each other in exact register across the width and the two ends of the cloth are temporarily held in a fixed position on the table 'by weights or some other means.
Commencing at one edge of the looped fabric, or at desired positions across the width of the fabric if more than one operator is working on the hand laced seam, two
opposing warp strands are tied together with a slip knot. One of the tied together warp strands is withdrawn from the body of the cloth at a desired distance back from the temporary seam, say three inches. The knot and the trailing opposing warp strand is pulled through the woven structure and out of the cloth at the point of withdrawal and, in so doing, is substituted for the original withdrawn Warp strand. This procedure is repeated alternately on opposite sides of the interface (the temporary joint of the fabric), and the extent of the weave back on each side of the interface is varied in a staggered pattern. The process of alternately pulling through warp strands is repeated across the full width of the fabric until the seam is complete.
The slip knots are now undone and the ends of the warp strands extending from the surface of the fabric are secured together permanently at the surface of the fabric. In one manner, the ends of the warp strands are tied together, preferably so that the knot will be as much under the surface plane of the fabric as possible. The fabric is then coated, preferably with a coating of polyurethane. However, a preferred manner of finishing the fabric is to first subject it to a coating of a synthetic resin material such as polyurethane and, after the coating has set and cured, to shear off the ends of the extending warp strands at the surface of the fabric, without knotting them.
The primary object of the invention is to provide a hand laced seam for loose woven fabrics which will have a tensile strength considerably greater than operating tensions on Fourdrinier paper machines.
A further object of the invention is to provide a fabric woven on a flat loom and to join a cut length of such fabric into an endless loop by means of a hand laced seam.
A further object of the invention is to provide a seam which is virtually invisible and maintains the Weave pattern across the seam.
A further object of the invention is to provide a scam in which opposing warp ends are joined in staggered pattern over the whole area of the seam.
A further object of the invention is to provide a seam in which opposing free ends of warp strands are looped and pulled throughthe woven structure, each adjacent pair of looped strands being pulled alternatively in opposite directions across the width of the fabric and in a staggered pattern.
A further object of the invention is to set the hand laced seam by a coating of a synthetic resin material.
A further object of the invention is to heat set and straighten the warp ends of a fabric prior to hand lacing for the purpose of facilitating the hand lacing operation. These and other objects of the invention will be apparent from the following detailed specification and the accompanying drawings, in which:
FIG. 1 is a partial longitudinal section of a port-ion of woven cloth before heat setting.
FIG. 2 is a view similar to FIG. 1 but after heat setting and showing the first stage operation of hand lacing the seam according to the present invention.
FIG. 3 is a view similar to FIG. 2 showing the progressive step of pulling the knotted opposed warp strands through the woven cloth.
FIG. 4 is a view similar to FIG. 2 but showing the further step of pulling the knotted warp strands out from the woven cloth.
FIG. 5 is a view similar to FIG. 4 but showing the woven cloth with the laced seam completed and after being coated with a synthetic resin to set the laced seam, and with the pulled out warp strands sheared off at the surface of the woven cloth.
FIG. 6 is a vertical section on the line 66 of FIG. 1.
FIG. 7 is a vertical section on the line 7-7 of FIG. 2.
FIG. 8 is a partial plan view showing the laced seam partially completed, with two adjacent pairs of warp strands tied with a slip knot and partially pulled through the woven fabric in opposite directions.
FIG. 9 is a partial plan view showing a section of completed seam with opposing pairs of warp strands sheared off in the manner shown in FIG. 5.
FIG. 10 is a partial plan view similar to FIG. 8 but showing an alternative method in which the opposing warp strands are knotted close within the woven fabric.
FIG. 11 is a partial plan view of a section of laced seam, with weft strands removed for clarity, showing the method of mating the opposing ends of the warp strands in a staggered pattern for greater strength of scam.
Referring to the drawings and particularly to FIGS. 1 to 5, which show the basic method of forming a hand laced scam in a woven fabric.
The fabric 5 is woven of warp strands 6 and weft strands 7 in any desired pattern. The strands 6 and 7 may be of synthetic or natural fibres or any combination of these.
The fabric 5 as originally woven has its warp strands crimped at 8 as shown in FIG. 1. For the purpose of this invention, the woven fabric is woven on a conventional flat loom and the fabric is cut longer than the required length necessary to form an endless loop. The cut length of fabric has its ends joined with a temporary seam to form a loop and the loop is set up on a heat-setting frame and is heat-set by simultaneously applying heat and tension to the fabric. This heat-setting operation results in the warp strands 6 being straightened out as shown at 6 in FIGS. 2 to 5 and crimping the weft strands as shown at 7 in FIG. 7.
The heat-set fabric is then cut to the required length plus about 12 inches.
Weft strands 7 are removed equally from both ends of the cut fabric which are to be joined by hand lacing, unt l the length of the fabric with undisturbed weft strands is equal to the desired finished loop length. This leaves free ends 9 and 10 of warp strands opposing each other.
The two ends A and B of the fabric 5 are now brought into matching interdigital conjunction, on a table or frame so that the last weft strands on each end lie on each side of the imaginary chain line C in FIG. 8. The corresponding opposite warp ends 9 and 10 are then knotted with a slip knot 11, see FIGS. 2, 3, 4, 6 and 8. The slip knots 11 in alternate joined ends of warp strands 9 and 10 should be formed so that the knot is formed alternatively in strands 9-10-9-10 for efiicient pull through the weave as will be explained later.
The tied ends of warp strands 9 and 10 are alternately interlaced back and forth into the junction of the two ends A and B of the fabric on either side of the junction indicated by the chain line C (FIG. 8). This is done by pulling the warp strand in question into the opposite side of the line C by means of the opposed warp strand and the knot which is attached to it.
Referring particularly to FIGS. 2, 3 and 8. A warp strand 9 or 10 is teased out of the undisturbed portion of the fabric A or B in the form of a loop 12 by means of a needle 13. The tying portion of the slip knot 11 should be on the warp end being pulled by the needle 13 While the tied end of warp strand will trail. This ensures that the slip knot 11 will not unslip during the pulling through operation.
The warp strand is pulled upwards from the fabric by the needle 13 and knot 11 is simultaneously pulled into the woven structure, dragging the opposite strand behind it with greater or less resistance depending on the openness of the weave. The more open the weave the more the weft strands 7 will flex to allow passage of the knot 11, see FIG. 3. By this method the opposing warp strand can be pulled into the opposite woven structure A or B to the required distance. This procedure is repeated alter n-ately on opposite sides of the junction. The extent of the Weave back from the imaginary line C as indicated by the withdrawal of the knot 11 from the fabric, see FIG. 4, is varied in a staggered pattern, one of which is shown in FIG. 11. The purpose of the staggering is to prevent the final woven warp end junctions from lying too close to each other.
After the hand laced seam is completed, the endless loop is again set up on a frame and tension is applied to the belt. This tension helps to straighten out any inequalities in the hand lacing operation. Final adjustments such as checking and straightening out any inequalities in the weave over the area of the hand laced seam are made at this time.
Final finishing of the hand laced seam can be ac complished by various methods. One such method is as follows:
While the belt is still under tension on the frame the tied warp ends 9 and 10 extending from the surface of the fabric are cut short. The seam, or if preferred, the whole fabric is given a coating of synthetic resin material such as polyurethane of the type set forth in co-pending United States patent application Ser. No. 443,647 in the name of D. G. MacBean, C. W. Cooper, and N. I. Broadway. After the coating has set and cured, the ends 9 and 19 of the warp strands 9 and 10 are sheared off close to the adjacent surface of the fabric as shown in FIGS. 5 and 9. It is desirable that these ends 9 and 10 overlap each other and be bonded together and to the adjacent weft strands for maximum strength.
In another form of finished joint the slip knots 11 are cut out and are again tied with a tight knot 14, see FIG. 10, as close under the surface of the fabric as possible. The fabric is then coated as above described. The knots 14, of course, are distributed in a staggered pattern as shown in FIG. 11.
In the manufacture of the above described hand laced seam it is preferable that the pull through the warp strands, particularly on fabrics for use in the Fourdrinier section of paper machines, be carried out on the side of the fabric which will be in contact with the machine.
This will ensure that the paper carrying surface of the fabric will retain its original woven surface undisturbed by knots or cut ends.
The seam can obviously be made in many configurations and sizes, but the most important factor controlling the strength of the seam is its size, that is its extension on either side of the original junction. For example, in cloth woven in the manner illustrated, having 22 strands per inch in the warp direction and 26 strands per inch the weft direction, and using multifilament polyester (Dacron) strands in the warp direction such as to give a tensile strength in this direction of about 430 pounds per inch, it has been found that a seam with a 12 inch length has a strength of 330 pounds, that is percent of the strength of the cloth. A five inch seam has a strength of pounds or 40 percent of the strength of the original cloth. A seam of about nine inches has been found most practical in a Fourdrinier wire. Actual tests have shown that the tensile strength of the seam above described is in the order of 700% of operating tensions.
The above is one example and it will be understood that for finer cloths or for applications where severe tensile loads and rough usage is not encountered, that smaller seam strength will be practical.
The for-med seam and the staggered warp strand ends are practically invisible in the finished belt, particularly as the warp strand ends are brought out and sheared off on the machine side of the belt. This has the effect of reducing the possibility of wire marking on the paper produced on the belt.
By heat setting the length of fabric before formation of the belt, whereby the warp strands are straightened and the weft strands are crimped, the crimped weft strands will take all of the wear While the straightened warp strands will be unaffected by wear thus retaining maximum tensile strength.
What I claim is:
1. The method of joining the end portions of a strip of screen or fabric formed of woven warp and weft strands to form an endless loop comprising (1) joining a cut length of the screen or fabric with a temporary seam, (2) heat setting the loop to straighten the Warp strands and thereby lengthening the loop (3) cutting the set fabric to the length required to form the finished loop plus approximately 12 inches, (4) removing weft strands equally from each end of the fabric until the fabric with undisturbed weft strands has the required length, (5) bringing the two ends of the fabric together into matching inter-digital conjunction and holding them together temporarily, (6) knotting the cor-responding free warp ends together, (7) pulling alternate knotted warp strands on opposite sides of the junction line of the ends through a length of the weave in a direction away from the junction line, (8) setting the laced seam by the application of a coating of synthetic plastic material and, (9) trimming the ends of the drawn-through warp strands close to the surface of the fabric.
2. The method as set forth in claim 1 in which the finished looped fabric is a Fourdrinier wire and the joined warp ends are pulled through on the machine side of the fabric.
3. The method as set forth in claim 1 in which the straightening of the warp strands effect crimping of the Weft strands to form openings through which the knotted ends of warp strands are pulled through.
4. The method as set forth in claim 1 in which the joined warp ends are joined with a slip knot and the slip knot strands are the strands which are pulled through the weaves with the strands about which the slip knot is formed trailing the pulled strands.
5. The method as set forth in claim 1 in which the joined warp strand ends are pulled out of the weave in a staggered pattern over the whole area of the seam.
6. The method as set forth in claim 1 in which the drawn through ends of warp strands are knotted close into the body of the weave before application of the coating of synthetic plastic material.
7. The method as set forth in claim 1 in which the coating of synthetic plastic material is polyurethane resin.
8. The method as set forth in claim 1 in which the trimmed ends of opposing warp strands are set in side by side arrangement and are sealed together by the coating of synthetic plastic material.
9. An endless belt for the Fourdrinier ends of paper machines and the like in which the fabric of the belt has been woven of warp and Weft strands on a flat loom and stretched in the direction of the warp strands to straighten the warp strands and crimp the Weft strands, and in which a series of weft strands has been removed from each end of the fabric to leave exposed extended ends of warp strands before joining the ends of the fabric into the endless belt by a hand laced seam; the said hand laced seam comprising an interweave of the said extended warp ends with the adjacent weft strands of the opposing ends of the length of fabric, the said extended warp ends being drawn through the adjacent weft strands of the opposing ends of the fabric from Which the original weft strand ends have been withdrawn out of the fabric to leave openings in the weft strands for the drawn through warp strand ends, the drawn through warp strand ends continuing the original weave of the fabric, and a coating of synthetic plastic material applied to the said scam, the said coating locking the weave of the said seam.
10. An endless belt as set forth in claim 9 in which the ends of the opposing withdrawn and threaded through Warp strand ends are located adjacent each other in a staggered pattern across the seam.
11. An endless belt as set forth in claim 9 in which the ends of the opposing withdrawn and threaded through Warp strands are knotted, and the knotted ends are arranged in a staggered pattern across the seam.
12. An endless belt as set forth in claim 9 in which the warp strand ends are trimmed close to the surface of the fabric.
13. An endless belt as set forth in claim 9 in which the knuckles formed by the crimped weft strands form the wear surfaces of the belt and protect the said straightened warp strands from Wear.
References Cited UNITED STATES PATENTS 1,261,118 4/1918 Geisel 24-38 2,441,460 5/1948 Walters 74232 2,748,445 6/ 1956 Skeer et al 28-72 X 3,060,547 10/ 1962 MacBean 28-72 FOREIGN PATENTS 221,926 11/1961 Austria.
11,073 6/ 1956 Germany. 68,405 10/ 1944 Norway.
MERVIN STEIN, Primary Examiner. L. K. RIMRODT, Examiner.