US 3584347 A
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Description (OCR text may contain errors)
June 15, 1971 K. A. KLENZ CLIPPI'NG DEVICE Filed May 27, 1970 INVENTOR.
KARL A. KLENZ United States Patent 3,584,347 CLIPPING DEVICE Karl A. Klenz, Oakland, Calif., assignor to Rheem Manufacturing Company, New York, N.Y. Filed May 27, 1970, Ser. No. 40,853 Int. Cl. B65d 77/18; F16b 2/26 US. Cl. 24-30.5W 9 Claims ABSTRACT OF THE DISCLOSURE A deformable generally U-shaped sealing clip for providing a tight seal around the neck of a flexible container. The clip is shaped in cross section to provide optimum strength and is formed along its inner side to seal material that is particularly resistant to deformation.
This invention relates to apparatus for applying a deformable sealing clip around the mouth of a flexible container such as a sausage casing, plastic bag, and the like. More particularly the invention is directed to a generally U-shaped deformable sealing clip somewhat similar to that shown in US. Pat. No. 3,400,433 and the present invention may be considered to be an improvement over said patent insofar as the clip disclosed herein be adaptable for use with plastic film having greater than normal resistance to deformation.
In the cited patent there is disclosed a clip particularly adapted to provide an effective seal by applying a strong radially inwardly directed sealing force to the material of the container and at the same time provide protection against crushing such material to an extent causing the material to fail, thereby destroying it for its intended purpose.
The film materials from which flexible containers such as sausage casings, plastic bags, and the like are made are continually being improved with respect to their toughness and reliability against failure. As the practical applications for such plastic film become more diversified the requirement of toughness and resistance to deformation have become greater so that there are materials presently on the market which are of such a high degree of toughness and resistance to deformation that it is extremely difiicult to apply sufiicient loading on the same to provide an eifective airtight seal. When it is attempted to encircle the mouth of a bag for example made from such new materials with a crossover U-shaped clip it has become difiicult to keep the physical dimensions of the clip within a reasonable limit and at the same time obtain optimum resistance to bending and the required unit pressure on the plastic material. The present invention is directed to a solution of this particular problem involving plastic materials having more than normal resistance to deformation.
The main object of the present invention is therefore the provision of a U-shaped clip of novel cross section which is formed to provide optimum resistance to the radially outwardly directed forces exerted by the plastic material and at the same time exert sufficient inwardly directed forces to deform such high strength materials to the point at which an airtight seal may be effected without causing failure of the material.
Other objects and advantages will be apparent from the following specification and from the drawing:
FIG. 1 is a semischematic side view showing a clip of the present invention with the associated punch and die at the point at which the legs of the clip are about to be deformed inwardly toward each other.
FIG. 2 is a cross sectional view through the sealed material showing the clip in its final deformed condition.
3,584,347 Patented June 15, 1971 FIG. 3 is a fragmentary side elevation of a sausage casing showing the clip applied thereto.
FIG. 4 is an enlarged cross section through the clip.
The clip generally designated 10 is adapted to be urged against a die A by a punch B in order to deform the clip around the neck C of the container to be sealed. Referring to FIG. 1 the undeformed clip 10 comprises a pair of opposed legs 11, 12 which are connected together at one of their corresponding ends by a crown 13 joined to said legs by curved junctures 14 and 15. The legs 11, 12 are straight and may be considered parallel except that it is preferable that they flair outwardly slightly at their free ends to facilitate controlled feeding of the clip along the feed track (not shown). The crown piece 15 is straight and may be considered perpendicular to the axes of legs 11, 12. The junctures 14, 15 are formed to a relatively sharp radius but one that is sufficiently large so as not to distort the wire excessively during the bending operation of forming the clip. The clip may be formed of various materials including steel and aluminum and it is preferably cold-worked to the shape shown in FIG. 1.
The cross sectional shape of the clip 10 shown in FIG. 4 is generally semicircular along its inner article engaging side and is generally trapezoidal along its outer side.
In greater detail, the inner article engaging side of the clip is provided with a central flat portion F to which the arcuate portions R constituting the remainder of the inner side are tangent. In other words the centers of curvature of the portions R are spaced apart the slight distance F to provide the central flat portion of the article engaging side.
The outer portion of the clip is generally trapezoidal and is formed to provide a flat outwardly directed face A which is adapted to receive any desired imprinting which may be applied to the same. (See for example US. patent application Ser. No. 696,890 filed Ian. 10, 1968.) The inner side of the trapezoidal section has a width W and is spaced outwardly from the arcuate portions R by a relatively narrow flat section G.
The function of the flat inwardly directed portion F is to reduce the otherwise excessive localized bearing forces which would result if the inner section were exactly semicircular in shape. It will be understood in this connection that such a circular inwardly directed inner section would present essentially line contact at the central portion of the clip which would have a severe cutting effect on the material to be sealed. By making the flat section F of a width about /8 the entire width W of the clip such excessively high localized pressures are reduced to a point that a cutting effect is obviated. However, it will be understood that extremely high pressures are nevertheless obtained at the central portion of the clip in view of the fact that the portions R diverge away from such central portion thus causing high radially inwardly directed pressure to be applied to the material at said central portion. On the other hand it will also be seen that the outer portions of the arcuate sections R nevertheless cause sealing forces to be applied along substantially the entire width W even though said sealing forces at said outer portions may be considerably less in intensity than those applied to the central portion of the article engaging side.
In order to avoid making the clip to unreasonably large dimensions the outer trapezoidal section is employed to obtain optimum section modulus for the amount of material used so as to resist the high radially outwardly directed forces applied on the closed clip by the sealed material. In this connection if the inner side of the clip is considered to be of substantially circular shape it can be shown that the section modulus of the outer trapezoidal portion is twice that of a semicircle if the wire were made round and of a radius equal to the average radius of the inner portion of the clip defined by arcuate sections R and the flat portion F. For this reason the provision of the outer trapezoidal section in effect increases the section modulus by at least 50% over that of a corresponding round wire of a radius approximating R.
As noted above the outer flat face A permits imprinting thereon and the outwardly converging side walls of the trapezoidal portion facilitate feeding the clip along the clip track. Additional improvement of the section modulus of the clip is obtained by moving the trapezoidal portion outwardly from the centers of curvature of the sections R by the relatively small amount indicated at G.
Although minor variations in the exact dimensions of the clip may be made and still obtain the benefits of the present invention it has been found that a clip of the shape shown in FIG. 4 having a depth D and width W should have a flat section F of a width approximately /8 of the width W. In order to obtain the desired section modulus the offset G between the substantially circular inner portion and the outer trapezoidal portion need not be more than about of the depth D. The width A of the outwardly directed flat face is preferably slightly larger than one half the width W. The total depth D of the clip is about 25% greater than the width W.
Although the above described clip is somewhat more expensive to make than a clip of more conventional circular cross section the cost of the material for forming the clip is considerably less than an equally effective clip of circular cross section. Furthermore in order to obtain the desired resistance to bending the diameter of a circular cross section clip would have to be greater than a practical size and at the same time such a circular cross sectional clip would still provide the disadvantage of creating higher than permissible localized stress at the central portion of the inner side of the clip.
1. A fastener for forming a tight seal around an article such as the mouth of a flexible container comprising:
an initially generally U-shaped clip having a pair of opposed legs and a crown connecting corresponding ends of said legs,
said legs being adapted to be deformed toward each other and into encircling relation with such article, said clip being formed of wire of generally uniform cross section throughout its length and being shaped in cross section to provide a substantially semicircular article engaging inner side and a pair of opposite sides converting outwardly of said clip from said inner side.
2. A fastener according to claim 1 wherein said pair of sides are substantially flat.
3. A fastener according to claim 1 wherein said inner side is formed with a fiat central portion having a relatively narrow width compared to the width of said clip.
4. A fastener according to claim 3 wherein said inner side is formed to circular arcs between the side edges of said fiat portion and said opposite sides.
5. A fastener according to claim 3 wherein said flat central portion is substantially A; the width of said clip.
6. A fastener according to claim 1 wherein the depth of said clip is substantially greater than the diameter of a circle having a radius equal to the average radius of said article engaging side.
7. A fastener according to claim 6 wherein said depth of said clip is about 25% greater than the diameter of such article.
#8. A fastener according to claim 6 wherein the outer side of said clip is flat and of a width about one half the width of said clip.
9. A fastener according to claim 1 wherein the outer portion of said clip is substantially trapezoidal in cross section with a flat outer side equal in Width to about one half the depth of said clip.
References Cited UNITED STATES PATENTS 3,473,430 10/1969 Niedecker '85-49 FOREIGN PATENTS 793,126 4/ 1958 Great Britain 49 634,895 12/ 1927 France 85-49 DONALD A. GRIFFIN, Primary Examiner US. Cl. X.-R. 85-49 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,584 ,347 D t d June 15 1971 l Karl A. Klenz It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 4, line 23, claim 7, before the period insert engaging side Signed and sealed this 29th day of August 1972.
EDWARD M .FLETCHER,JR ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO- USCOMM-DC wan-pen Q \l GOVERNMENT PRINTING OFFOCE: IDID 0"356'33,