US3400433A - Clipping device - Google Patents

Description

Sept. 10, 1968 K. A. KLENZ I CLIPPING DEVICE Filed May 29, 1967' rill-I INVENTOR. KARL A. KLENZ g g, M.

United States Patent "ice 3,400,433 CLIPPING DEVICE Karl A. Klenz, Oakland, Calif., assignor to Rheem Manufacturing Company, New York, N.Y., a corporation of California Filed May 29, 1967, Ser. No. 642,028 7 Claims. (Cl. 24-305) 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 to provide a cross section of optimum strength with a relatively flat side against the material of the container neck.

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 adapted to be applied around the neck of a flexible container for providing an air tight seal such as is required when the container is evacuated to maintain the product therein under a vacuum.

In the packaging of vacuum packed products, such as meat, cheese, poultry, and the like, it is essential that a perfect seal be applied so as to prevent spoilage of the product by the leakage of air into the container. Heretofore numerous attampts have been made to improve clipping apparatus and sealing clips to the end that optimum sealing effect is achieved. The most important advance in this art has been the provision of the so called cross over clip which comprises a U-shaped clip deformed around the mouth or neck of the container so that the opposed legs of the clip cross each other during the deforming step and are brought into side by side closely adjoining relationship. The importance of the cross over type of clip is set forth in some detail in US. Patent No. 3,266,138. Cross over type clips are also disclosed in US. Patents Nos. 2,265,277, 2,682,054, 1,963,306, 2,130,779, 3,026,521, 3,210,835, 3,224,083, 3,239,926, and 3,293,736.

In those applications wherein extended shelf life of a hermetic seal is not essential it has been customary in the past to apply what is generally known as a butt type clip. Such butt type clips are usually made from broad fiat material and are also generally U-shaped and applied to the material to be sealed by urging the legs of the clip toward the crown of the clip which connects the opposite legs together. Such fiat butt type clips have a relatively low section modulus and have not been dependable in effecting an air tight seal and their function has been usually restricted to merely providing a closure for the container. Examples of such butt type clips may be seen in US. Patents Nos. 2,639,875, 2,700,805, 2,756,428, 2,812,628, 2,855,647, and 2,972,747.

As pointed out in the above noted Patent No. 3,266,138, it is important in providing an air tight seal to apply extremely high radially inwardly directed compressive forces on the material of the container mouth in order to 3,400,433 Patented Sept. 10, 1968 prevent leakage. This is especially true in the case of bags and other containers made of modern tough resilient plastics. When a clip is applied to seal the neck of a container formed of relatively frangible material, such as cellulose, the application of high radially inwardly directed pressures has, in many instances, resulted in such material being crushed and severed thereby destroying it for its intended purpose.

The above noted crushing effect is in part attributable to the fact that wire of a round cross section has been used almost uniformly in the prior art for providing cross over clips. In this connection it will be apparent that the inner element of a U-shaped clip formed of wire of circular cross section is a U-shaped line which engages the material first as the clip is deformed into a closed loop surrounding the mouth of the container. The fact that the material of the container is extremely flexible would suggest that the particular cross section of the wire from which the clip is formed is not of any particular significance, however, it has actually been found that a substantial reduction in the unit pressure on the material may be effected by making the inner side of the U-shaped clip flat instead of semicircular as is the case in the clip made of wire of circular cross section.

It has also been found that the sealing effect of a clip is proportional to the width of the clip as well as the radially inwardly directed pressure which the clip exerts. Flat clips of the nontight type are usually quite wide, but as noted above no successful attempt has been made in the past to make such clips sufliciently tight to retain the seal of a vacuumized bag, especially when one clip size is employed to seal different amounts of material. Furthermore, the section modulus of such flat clips is usually insufficient to resist the outwardly directed pres sure of the material tending to open the seal.

The main object of the present invention is the provision of a novel clip which lends itself to use in creating an efficient seal around the neck of a flexible container and at the same time is less likely than prior art clips to cause failure of the material when the necessarily high pressures are applied to such material.

Another object of the invention is the provision of an improved clip for use either as a nontight or air tight seal and made of wire of a cross section satisfying most of the practical requirements existing in apparatus of the subject type.

Another object of the invention is the provision of a novel sealing clip which is adapted to effect a better air tight seal than has heretofore been possible and without any increase in expense of making the clip.

Other objects and advantages will be apparent from the following specification and from the drawings.

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 greatly enlarged typical cross section through one form of the clip.

FIG. 3 is a similar cross section through the preferred form of clip contemplated by the present invention.

FIG. 4 is a cross section similar to FIG. 3 showing a modified form thereof.

FIG. 5 is a cross section through the mouth of a sealed container showing the clip deformed therearound.

FIG. 6 is a fragmentary side elevation of a sausage casing showing the clip of FIG. 3 applied thereto.

As is described in greater detail in US. Patent No. 3,266,138, 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, 15. The legs 11, 12 are straight and may be considered parallel except that it is preferable that they flare outwardly slightly at their free ends to facilitate controlled feeding of the clip along the feed track (not shown). The crown piece 13 is straight and may be considered perendicular to the axes of legs 11 and 12. The junctures 14, 15 are formed to a relatively sharp radius but one that is sufliciently 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 section of the clip 10, shown in FIG. 2, is generally triangular with rounded corners and is uniform throughout its length. The cross sectional contour of the clip is such that a relatively wide side is presented to the material to be compressed and sealed. The remaining sides 21, 22 converge away from the inner side 20. It is therefore apparent that the extremely high localized pressures which attend the use of a clip of circular cross section are not present and the clamping forces are spread over the entire width W of the clip. As pointed out above, not only is the flat side 20 desirable for the purpose of minimizing localized stress but the increase in width of the inner side of the clip in a direction along the neck of the bag increases the sealing effect and thereby reduces the likelihood of the container leaking.

As an example it has been found that in a clip formed to a cross section as shown in FIG. 2 with the width W equal to .1" and the depth of the section D equal to .1" the resultant sealing effect is improved over a clip of round cross section having a diameter of .07" and an equivalent section modulus.

Another important feature of the cross section of the clip shown in FIG. 2 is that the unit tensile strength is not as great as in a clip of circular cross section since the deformed clip is in effect a curved beam (FIG. 5) and as such should have more material adjacent its center of curvature than at a point further away from said center. For this reason excessive stresses and deflections of the fibers of the material are avoided.

Another advantage of the section of FIG. 2 resides in the fact that the clip is more easily controlled while feeding the same along the feed channel of the clipping device than a clip of circular cross section.

The strength of the clip may be enhanced and certain additional advantages obtained by the preferred form of cross section shown in FIG. 3. In this case the section 10' is trapezoidal with the width of the narrower side 23 being preferably at least one half the maximum width W of the inner side 24 which engages the material to be sealed. The depth D of the cross section may be substantially equal to the width W. It will be apparent that the section modulus of the trapezoidal section is considerably greater than the section modulus of the triangular section and, in fact, is more than twice as great. For this reason the resistance of the closed clip to opening under the radially outwardly directed pressure of the deformed material of the container is substantially greater than the corresponding resistance of a clip of circular cross section having an equivalent area.

As an example, if the width W and the depth or thickness D are each made equal to .1", the section modulus about its neutral axis of the section of FIG. 3 is greater than the corresponding section modulus of a circular section of .1" diameter. It will be understood that the general comparison of resistance to bending of trapezoidal and round clips remains about the same even if the neutral axis is moved toward the inner side 24 as is the case if the loop of FIG. 5 is considered to be a curved beam.

As is the case with the triangular clip of FIG. 2, the trapezoidal clip of FIG. 3 has the advantage of being easily controlled while being fed along the clip channel of the feed track. In this connection it will be noted that the converging sides 25, 26 of the clip present fiat surfaces adapted to be engaged by complementarily formed inner sides of the feed track. It is therefore not necessary to engage the clip during feeding along the outer side 23 and said outer side is available for imprinting a code number on the clip to identify, for example, the plant in which the product is manufactured. Since the outer side 23 need not engage the track channel there is no likelihood of the imprinted indicia being smeared or otherwise damaged during the deforming step.

The clip of the present invention also has the advantage of providing a flat surface on the outer sides of the clip so that an adhesive tape for securing together a plurality of clips engages a greater area than in the case of a clip of circular cross section.

With some materials it has been found that an increase in sealing effect may be obtained by providing a relatively small groove along the inner side of the clip as shown in FIG. 4. In this case the clip 10" is substantially the same as that shown in FIG. 3 except that the wire of the clip is formed with a shallow longitudinally extending groove 27 along the inner face 28. With extremely resilient materials it has been found that relief of the high pressures resulting from the deformation of the clip is obtained without impairment of the sealing effect by the incorporation of the groove 27.

The use of the above described clip for sealing a vacuumized container has been emphasized because such use presents the greatest problems. However it will be understood that the clip is equally applicable to other uses. For example, in many instances the container is subjected to internal pressure rather than a vacuum. In such cases the improved resistance of the clip to opening under the internal pressure at the neck is equally advantageous. Similarly, in those instances where the weight of the contents is applied to the clip, as when the product is suspended, the resistance of the clip to slipping along the length of the container neck is especially important. As pointed out above the form of FIG. 4 is particularly advantageous in this latter application.

The very specific description given above of the preferred form of the invention is not to be taken as restrictive as it will be apparent that various modifications will occur to those skilled in the art without departing from the scope of the following claims.

I claim:

1. A fastener for forming a tight seal around an article such as the mouth of a flexible container comprising:

a clip being initially generally U-shaped having a pair of opposed legs and a crown connecting the corresponding ends of said legs,

said legs being adapted to be deformed toward each other into encircling relation with such article,

said clip being formed of wire of generally uniform cross section throughout its length and being shaped to provide one substantially flat article engaging side inner side directed inwardly of said clip and a pair of opposite sides converging outwardly of said clip from said one side.

2. A fastener according to claim 1 wherein said inner side is provided with a groove extending along the entire length of said inner side.

3. A fastener according to claim 1 wherein the cross sectional contour of said wire is generally in the form of a triangle with rounded corners connecting the sides of said triangle.

4. A fastener according to claim 1 wherein the thickness of said clip in a direction at right angles to said one side is substantially equal to the width of said one side.

5. A fastener according to claim 1 wherein the cross sectional contour of said clip is substantially trapezoidal.

6. A fastener according to claim 5 wherein the width of the side opposite said inner side is about one half the width of said inner side.

7. A fastener according to claim 6 wherein the depth of said clip at right angles to said inner side is sul'ficiently great that the section modulus of the cross sectional area about its neutral axis is substantially equal to the corresponding section modulus of a circular area having a diameter equal to the width of said inner side.

References Cited UNITED STATES PATENTS 647,693 4/ 1900 Blantz. 2,972,791 2/1961 Kelem 24-30.5 3,266,138 8/1966 Tipper 85-49 XR FOREIGN PATENTS 717,308 10/1931 France.

793,126 4/1958 Great Britain.

985,012 3/1965 Great Britain.

529,968 6/ 1955 Italy.

DONALD A. GRIFFIN, Primary Examiner.

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