US 3533891 A
Description (OCR text may contain errors)
Oct. y13, 1970 A A w. R. r-#uY-EAARv 3,533,891
JOINTED STRIPS oF SHEET-METAL AND METHOD `of' MAKING SAME Filed Dec. 7, 1967 rA12/QAM Mw/ United States Patent O 3,533,891 JOINTED STRIPS OF SHEET METAL AND METHOD OF MAKING SAME Wallace R. Puyear, 5569 Maceri Lane, Flint, Mich. 40507 Filed Dec. 7, 1967, Ser. No. 688,885 Int. Cl. B32b 3/22 U.S. Cl. 161-38 17 Claims ABSTRACT OF THE DISCLOSURE The leading edge of a strip of sheet metal is joined to the trailing edge of another strip 'by a transverse strip of flexible non-metallic tape having reinforcing filaments running in an oblique angle with respect to the width of the metal sheets.
This invention relates to the metal working field, and more particularly to that aspect of the field in which long strips of sheet metal are fed to what are known as progressive die machines. Machines of this type are provided with a series of dies, as many as twelve or more, each of which dies represents a stage in the formation of a three dimensional object from a flat strip of metal.
This metal is supplied to the fabricator in the shape of a coil which must -be fed into the progressive die machine in a step by step operation. At the start of operations metal must be fed completely through all of the die forming operations in the machine manually, after which further stamping operations are continued with the strip being fed automatically through the machine in step by step fashion after each raising of the upper die holder. However, each time the machine comes to the end of a coil of metal the machine must be stopped and the leading edge of a succeeding sheet of metal must be fed into the machine manually in the same fashion as the first sheet =was passed through the machine. In each case this advancing of the leading end of a strip must be done manually and is fairly time consuming Iby comparison with the normal operating speed of the machine.
In order to reduce the time for introducing a new strip of metal into the machine, various methods have been tried for attaching the leading edge of a new strip to the trailing edge of the old strip in such a manner as to permit the new sheet to thread its way through the machine automatically. One such method which has been tried comprises butt welding the end of one strip to the end of the other, but this is unsatisfactory since the metal at the weld itself often is harder and less ductile than the remainder of the strip and, on occasion, when this welded portion of the two strips has ibecome positioned in one of the dies of the machine, the die has been damaged or even broken.
Another method of attaching two strips together has comprised the use of a patching strip of non-metallic material, this patching strip being adhesively secured to the two strips so as to bridge the joint between the two strips. Non-metallic material which have been used for this purpose include pressure sensitive tapes having reinforcing filaments of high tensile strength material such as glass fiber, these reinforcing filaments running longitudinally of the tape itself. However, when these reinforced tapes have -been used they have been applied in the obvious manner, with the reinforcing filaments running in the direction of stress, namely along the length of the strip, since the purpose of applying the tape is to enable the leading strip to pull the following strip through the machine in the normal direction of travel.
However, it has been found that this latter method is also unsatisfactory for the reason that there is always Patented Oct. 13, 1970 lCe a tendency on the part of the two strips of metal to liex at the point of junction between them. In practice, in view of the fact that the metal is comparatively rigid by comparison with the joining tapes and that the supply roll may be located at a distance from the machine, a certain amount of bending normally does take place at the joint with the result that the non-metallic tape material is forced to act as a hinge. The result is that the reinforcing fibers in the tape are cut and broken by contact With the jagged edges of the two strips of metal.
Suprisingly enough it has been found that non-metallic tape, such as the commercially available cellulose acetate pressure sensitive tapes having closely spaced longitudinally running glass filament reinforcing elements can be quite satisfactorily employed for joining the strip metals with the reinforcing filaments disposed, not in the direction of the expected stress, but at an oblique angle with respect thereto. It is believed that the success of this type of joint is due to the fact that any hinging action that may take place by relative bending of the two adjacent sheets of metal is not transmitted to the reinforcing filaments as a direct tensile stress Ibut only as a fractional component of the total stress.
Other objects and advantages will -be apparent to those skilled in the art after reading the following specification in connection with the annexed drawing, in which, FIG. l, is an isometric view of a supply roll of sheet metal having its leading end joined to the trailing end of another similar sheet of metal in accordance with the teachings of this invention; FIG. 2 is a plan view of an enlarged scale of the joint shown in FIG. 1; FIG. 3 is a crosssection on a still more enlarged scale taken on theA line 3-3 of FIG. 2, and; FIG. 4 is a cross-section taken on the line 4-4 of FIG. 2 and on the same scale as FIG. 3.
In the drawings, the numeral 10 indicates generally the trailing end of a strip of sheet metal being fed to a machine, such as a progressive die machine (not shown), and moving at a direction toward the right of the drawing, as shown by the arrow. Numeral 11 indicates generally the leading end of a coil, indicated generally by numeral 9, of a new supply of sheet metal joined to the trailing edge of the strip 10. Obviously the cross-sectional dimensions of the two strips 10 and 11 are approximately the same so that the new strip will pass through the machine without difficulty.
While in normal practice the trailing edge 12 of strip 10 and the leading edge 13 of the following strip would be cut off on straight lines at right angles to the length of the strips, it is obvious that there will be occasional irregularities in the angles of these margins. In general the two abutting edges of the strips will be parallel to each other. However in joining the two strips it has been desirable to leave a small gap, indicated generally by numeral 14, between the two margins, the width of this gap being approximately equal to the thickness of the sheets.
In one form of the invention the material used for securing the sheets together is a non-metallic tape having a pressure sensitive adhesive material on one side with a series of closely spaced reinforcing filaments embodied in the tape or adhering to one side thereof and extending along the length thereof. f
Two such tapes suitable for the purpose are listed in the tape data index published by 3-M Manufacturing Company under the Scotch brand of pressure sensitive tapes. These are identified under the heading of Acetate Fiber, Film, filament tape numbers 890, 898, transparent glass filament. Number 890 has a thickness of .008 inch and a tensile strength of 500 pounds for a one inch wide tape with a stretch before breaking of 3% of its length and is provided with a pressure sensitive adhesive requiring 45 pounds to pull a 1 inch wide strip of tape from a steel surface according to ASTM standard methods.
Number 898 has a thickness of .007 inch and a tensile strength of 340 pounds for a one inch wide tape with a stretch of 3% and an adhesive force of 40 pounds for a one inch wide strip according to the tests recognized by the ASTM. However, it should be understood that the invention is not limited to the use of these specific materials.
While it is possible to provide a joint using the above mentioned pressure sensitive tapes applied directly to the metal it has been found preferable to apply a high performance contact type adhesive to the metal prior to the application of the tape. One such adhesive, although not to be considered as limiting, is that produced in accordance with the 3-M Company Products Specification No. 1357 dated Oct. l, 1966, and sold under the Scotch- Grit brand. Such a product basically comprises a polychloroprene base and initially has a consistency of a thin syrup which may be applied by either by spraying or brushing.
In making the joint the two metal strips and 11 are brought into alignment with one another, as shown in FIGS. 1 and 2, with the margins 12 and 13 adjacent but spaced from each other by the aforementioned gap 14. Preferably the area adjacent the margins of the strips should be either brushed or otherwise coated with a preliminary layer, indicated by numeral 15, of a contact adhesive on both sides of each strip. After the contact adhesive has been allowed to set the two longitudinally extending tapes 16 may be applied along both surfaces of the side margins and the side edges of the two strips (as shown in FIG. 4) and extending across the gap 14 approximately equally along both adjoining edges of the strips 10 and 11 and with the reinforcing filaments 17 running in the direction of the length of the metal strips. In addition, the transverse tapes 18a and 18b will be applied bridging the gap 14, one tape being applied to each side of the strip of metal. In this case the tapes 18a and 18b are arranged so that the reinforcing filaments 19a and 19b respectively, are disposed at an oblique angle with respect to the gap 14, with the filaments 19a also being arranged at an angle with respect to the filaments 19b of the tape on the reverse side of the joint. In this way it will be seen that any flexing of the strips 10 and 11 with respect to each other which would produce a hinging action about the axis of the gap 14 will not produce a direct stress in tension against the reinforcing filaments themselves. Any tendency towards exerting pull on the tapes 18a and 18b in the direction of the length of the metal strips will produce only a comparatively minor component of force in tension in the reinforcing filaments.
It has been found that even after repeated flexing of the strips 10 and 11 that no breakage occurs in the tapes 18a and 18b and, surprisingly enough, it has been found that the strength of these tapes is sufficient such that the longitudinally extending tapes 16 do not have their reinforcing filaments destroyed either. Repeated tests have been conducted on sample short lengths of metal bonded in this fashion by bending the strips about a 360 axes with respect to each other with no destruction of the joint created in accordance with the teachings of this invention.
It should also be noted that While it has been stated that the tapes 16 may be applied first, it is not considered an essential aspect of the invention that this procedure necessarily be followed. It will be perfectly feasible to apply the transverse tapes prior to the application of the longitudinally running marginal tapes. It should also be observed that while, for the sake of clarity, in the drawing the transverse tape is shown as extending across the gap only to the edge of the longitudinal tape, the transverse tapes 18a and 18b could extend entirely across the width of the metal strips either underneath or above the surfaces of the marginal joining strips 16.
Having disclosed one form in which the invention may be practiced it will be understood that modifications and improvements may be made by those skilled in the art which would come within the scope of the annexed claims.
1. An article of the character described, comprising two strips of sheet metal of indeterminate length and approximately the same thickness positioned in longitudinal alignment spaced from each other by a narrow gap and joined to each other by a transverse joining strip of fiexible nonmetallic sheet material bonded to a surface of each of said metal strips and bridging said gap, said joining strip including a plurality of reinforcing filaments extending along axes disposed obliquely with respect to the space defining said gap between the metal strips.
2. The invention as defined in claim 1, wherein said metal strips are bonded by a pair of transverse joining strips of flexible non-metallic sheet material bonded to the respective opposite surfaces of said metal strips and bridging said gap, said joining strips including a plurality of reinforcing filaments extending along axes disposed obliquely with respect to the space defining said gap between the metal strips.
3. The invention as defined in claim 2, wherein the width of said gap is approximately equal to the thickness of said metal strips.
4. The invention as defined in claim 1, wherein at least one of the side margins of each metal strip is also positioned in substantial longitudinal alignment, and a marginal joining strip of non-metallic flexible sheet material having spaced reinforcing filaments is bonded to the surfaces of the metal strips adjacent said adjoining side margins, the reinforcing filaments of said marginal joining strip extending parallel with said margins.
5. The invention as defined in claim 4, wherein said metal strips are of approximately the same width and a second marginal joining strip of non-metallic flexible sheet material having closely-spaced reinforcing filaments is bonded to the surfaces of the metal strips adjacent the respective other side margins, the reinforcing filaments of the second joining strip also extending parallel with the margins, both said joining strips extending around the respective opposite side edges of the metal strips and being bonded to both surfaces of each metal strip adjacent both side margins.
6. The invention as defined in claim 5, wherein said joining strips are composed of cellulose acetate material having glass filaments embodied therewith.
7. The invention as defined in claim 6, wherein said joining strips include a pressure sensitive coating on one side thereof.
8. The invention as defined in claim 4, wherein said bond between the metal and the joining strips includes a contact adhesive.
9. Method of joining two strips of sheet metal of indeterminate length and approximately the same width and thickness, comprising the steps of placing said two sheet metal strips in longitudinal alignment and spaced from each other by a narrow gap; adhesively bonding a joining strip of narrow elongated non-metallic flexible sheet material having a plurality of closely spaced longitudinally extending reinforcing filaments embodied therewith to one surface of each said metal strip in a transverse direction adjacent said gap so as to bridge said gap across substantially the entire Width of the metal strip and to dispose the reinforcing filaments at an acute angle thereto.
10. The method as defined in claim 9, which includes the additional steps of adhesively bonding a second said joining strip to the opposite surfaces of each said metal strip to bridge said gap and to dispose the reinforcing filaments of the second joining strip at an acute angle thereto.
11. The method as defined in claim 10, which includes the step of disposing said second joining strip in a transverse direction angularly related to the transverse direction of the first joining strip.
12. The method as defined in claim 11, wherein said 5 joining strips are composed of a cellulose acetate material having glass filaments embodied therewith.
13. The method as defined in claim 9, which includes the step of applying a coating of contact adhesive to said sheet metal strips for bonding said joining strip thereto.
14. The method as defined in claim 9, which includes the step of applying a pressure sensitive adhesive coating to said joining strip and bonding said joining strip to thc metal strips by the application of pressure thereto.
15. The method as defined in claim 11, which includes the steps of applying to the metal strips an additional pair of joining strips of non-metallic flexible sheet material having a plurality of closely spaced reinforcing filaments embodied therewith, and bonding said joining strips to both surfaces of the side margins of the metal strips with the reinforcing laments extending longitudinally of the length of the metal strips.
16. The method as defined in claim 15, which includes the application of a coating of pressure sensitive adhesive to said joining strips, and the application of pressure to said strips for said bonding to the sheet metal strips.
17. The method as defined in claim 5, which includes the step of applying a coating of contact adhesive to said metal strips prior to bonding said joining strips thereto.
References Cited UNITED STATES PATENTS