US3763524A - Keying grip clamp for holding a thin flexible article - Google Patents

Abstract

Side edges of a flexible container are gripped near the unsealed container mouth by clamps to transversely tension the container and form a one-way valve at the container mouth which prevents entry of liquid into the container but permits the passage of gases from the container during cooking of a product within the container. The clamps hold the container''s side edges firmly throughout a wide range of temperature variation and despite the presence of slippery substances that tend to lubricate the surface of the container. Each clamp comprises a pair of opposed jaws connected for relative movement between an open position where the jaws are spaced from each other and a closed position where the jaws are in abutment with each other. A keyway having a generally rectangular cross section is provided in one jaw and a cylindrical key formed of resilient material projects from the other jaw into the keyway to grip therebetween a side edge of the flexible container. The container edge is bent around the corners of the keyway and anchored within the keyway.

Description

United States Patent [191 Wilson KEYING GRIP CLAMP FOR HOLDING A THIN FLEXIBLE ARTICLE [75] Inventor: Donald C. Wilson, San Jose, Calif. [73] Assignee: FMC Corporation, San Jose, Calif.

[22] Filed: July 24, 1972 [21] Appl. No.: 274,154

[52] US. Cl. 24/243 K [51] Int. Cl A44b 21/00 [58] Field of Search 99/185, 214;

24/243 R, 243 K, 243 M, 243 N, 263 FC, 263 R, 263 PJ, 263 PC, 248, 250, 252, 253

Primary Examiner-Donald A. Griffin Attorney-F. W. Anderson et al.

[57] ABSTRACT Side edges of a flexible container are gripped near the unsealed container mouth by clamps to transversely tension the container and form a one-way valve at the container mouth which prevents entry of liquid into the container but permits the passage of gases from the container during cooking of a product within the container. The clamps hold the containers side edges firmly throughout a wide range of temperature variation and despite the presence of slippery substances that tend to lubricate the surface of the container. Each clamp comprises a pair of opposed jaws connected for relative movement between an open position where the jaws are spaced from each other and a closed position where the jaws are in abutment with each other. A keyway having a generally rectangular cross section is provided in one jaw and a cylindrical key formed of resilient material projects from the other jaw into the keyway to grip therebetween a side edge of the flexible container. The container edge is bent around the corners of the keyway and anchored within the keyway.

5 Claims, 5 Drawing Figures KIIYING GRIP CLAMP FOR HOLDING A THIN FLEXIBLE ARTICLE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a clamp for anchoring an edge of a thin flexible article subjected to tension. Such clamps are particularly useful in connecting a flexible container to a carrier before the processing of the products therein by the method and apparatus disclosed in my US. Pat. No. 3,501,318 issued Mar. 17, 1970.

2. Description of the Prior Art Flexible containers made of heat sealable material are partially filled with a food product to be cooked or sterilized. The side edges of the filled, but unsealed, container are gripped at points slightly below the unsealed upper edge thereof, and the flexible container is stretched transversely to form a one-way valve allowing vapor, air and gases to escape while preventing liquids from entering. A desired tensioning force must be maintained between the gripped edges of the flexible container to have the valve function properly.

Problems have been encountered with known clamps for holding thin flexible material such as the side edges of a flexible container. Slippage of the container edge within the clamp reduces the tensioning force so that the valve may not function properly, and, should the edge become disengaged from the clamp, the food product within the container could either be discharged or diluted. The clamps should not be affected by substantial temperature changes because the flexible containers are attached to the carrier at room temperature but later subjected togreatly increased tem peratures during processing. The clamp grip cannot depend entirely upon surface friction with the flexible container since the surfaces thereof frequently become coated with slippery substances to reduce the coefficient of friction and only a minimal area on the container is available for gripping.

SUMMARY OF THE INVENTION A clamp with opposed jaws wherein a keyway is provided in one jaw and wherein a key projects from the opposite jaw can provide a firm grip'on a thin flexible article confined between the key and keyway even though the surface of the article may be coated with a slippery substance. Such a clamp has been found to provide significantly greater holding power than the prior art clamps because the thin flexible article must be drawn through a restricted passage with a series of bends therein in order to be withdrawn and the internal resistance of .the article provides a sufficient resistive force to prevent withdrawal.

The keyway is provided on one jaw face, and when a flexible article is trained thereabout, tension'force withinthe article isresisted by the jaw. This jaw is preferably made of rigid material with the keyway having a generally rectangular cross-section. The key is made of resilient material with, preferably, a circular crosssection and having a diameter greater than the depth of the keyway. This structure enables the key to readily fit within the keyway; however, when the key is compressed at the bottom of the keyway the flexible article will be tightly gripped. The keymay be formed for convenience by an annular member such as an O-ring which can be fitted around the jaw opposite the keyway and retained in place by grooves. This arrangement enables the key to move slightly in response to lateral forces in order to provide the desired gripping force at the edge of the flexible article along one of the side faces of the keyway. Yieldable means are provided to continuously urge the jaws into engagement, and, in a preferred version of the clamp, the jaws are also resiliently mounted for joint lateral movement in order to provide a convenient means for inserting the edge of a flexible article between the jaws prior to the tensioning of the article.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a perspective view of a carrier upon which clamps embodying the present invention are mounted.

FIG. 2 is an enlarged plan view of one of the clamps shown in FIG. 1.

FIG. 3 is a section taken on the line 3-3 of FIG. 2.

FIG. 41 is an enlarged sectional view of the key and keyway illustrating the keying grip upon the edge of a thin flexible article.

FIG. 5 is an enlarged sectional view of the key and keyway illustrating the wedging action of the key when the article is tensioned.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. ll, a U-shaped container carrier MD is shown having end supports Ill and 112 with downwardly facing slots 13 and 14 to receive the ends of pivot pins, not shown, that project inward from a pair of parallel endless chains. These chains form a conveyor to transport the carrier through cooking apparatus as described in my aforementioned U.S. Pat. No. 3,501,318. A stationary clamp 16 is bolted within the U-shaped container carrier adjacent one end thereof and an adjustable clamp 17 is bolted within the carrier at the opposite end. These clamps are adapted to hold the opposite side edges of a flexible container 18 as indicated in phantom line in FIG. 1.

Adjustable clamp 17 includes a right side plate 20 bolted to one side of the U-shaped container carrier 10 and a left side plate 21 bolted to the opposite side of the container carrier. An elongated slot 22 is provided in the right side plate and a similar elongated slot 23 is provided in the left side plate opposite to and in alignment with slot 22. An operating pin 24 extends between the side plates through the elongated slots for slidable movement therein. A tension spring 25 couples the operating pin to an anchor pin 26 that is fitted through holes in the side plates and fixed in place. The anchor pin is held in place by retainer rings 27 and 28 (FIG. 2). The tension spring 2Surges the operating pin towards the end of the elongated slots nearest the anchor pin but permits movement of the operating pin away from the anchor pin when a container is to be inserted in the clamps.

A reversely bent strip 30 (FIG. 2) fits loosely about operating pin 24 between the side plates 20 and 21 and includes a central portion 31 extending parallel with the side plates to form a stationary jaw. A conventional O-ring 32 made of resilient material and having a circular cross-section fits around the stationary jaw and is retained within grooves 33 and 34 (FIG. 3) located, respectively, at the top and bottom of the jaw. The portion of the O-ring which projects toward the side plate 21 from the face of the jaw forms a key.

A movable jaw 36 is slidably fitted upon a small diameter portion of the operating pin 24 but is retained by a radial face 37 located intermediately of the pin where the small diameter is stepped to a larger diameter end portion of the pin for mounting to the side plate 20. A guide face 35 on the movable jaw contacts a transversely extending face of the bent strip 30 to maintain transverse alignment of the movable jaw on the operating pin. Within an enlarged end portion of the movable jaw is a keyway 38 having a substantially rectangular cross-section and being adapted to receive that portion of O-ring 32 which forms the key. Preferably, the depth of the keyway is approximately three-fourths the diameter of the key so that the key will be compressed when the jaws are closed. A compression spring 39 fits around the small diameter portion of pin 24 between a portion of bent strip 30 adjacent the left side plate 21 and the back side of the movable jaw 36. Thus, the movable jaw is urged towards the radial face 37 of pin 24 so that the key seats within the keyway.

FIG. 4 illustrates the manner in which the side edge of a flexible container 18 is gripped within keyway 38 between the movable jaw 36 and the key formed by O- ring 32. it should be noted that the key can shift laterally within the keyway since the O-ring is not rigidly attached to stationary jaw 31. Since the key is made of resilient material, there is no danger of shearing the side edge portion of the flexible container upon closing the jaws. Furthermore, with the key having a diameter greater than the depth of the keyway, the flexible container will always be gripped at the bottom of the keyway, and there will be relatively little pressure upon that portion of the flexible container that is between jaws 31 and 36 but outside of the keyway.

When a tension force is applied to flexible container 18 in the direction indicated by arrow 40 in FIG. 5, such force is resisted by a reaction at the rounded corner 41 between a face 42 of jaw 36 and a keyway face 43 substantially perpendicular thereto. Thus, the main tension force is transferred to jaw 36 and is not applied to the key formed by O-ring 32.

Jaw 36 is made of a rigid material, such as metal, while O-ring 32 is made of resilient material, such as rubber; thus, slippage is more likely to occur between the flexible container and the bottom surface of the keyway than between the flexible container and the key. Also, there is more area contact between the key and the flexible container than there is between the keyway and the flexible container. The key will thereby be compressed not only by compression spring 39, which forces jaw 36 against the flexible container, but also by tension in the flexible container and slippage at the bottom surface of the keyway which forces the key towards the side keyway face 43. It will be noted that the flexible container is tightly gripped between the key and keyway in a restricted passage that includes a series of sharp bends. Since the withdrawal of the flexible container from the keyway will be resisted by the internal resistance of the flexible container to bending within the restricted passage, particularly around corner 41, the performance of the clamp is independent of friction coefficients. Therefore, the clamp can hold a flexible container, resisting a tensioning force up to the yield strength of the material from which the flexible container is constructed, regardless of the surface conditions of the flexible container 18 or jaw 36. Thus these surfaces may be coated with lubricants or other slippery substances without significantly affecting the holding power of the clamp.

The structure of clamp 16 is similar to that previously described for clamp 17 with the exception that the operating clamp is retained in a stationary position by its operating pin 24 which is received in holes 22a (one only being shown) in the side plates 20a and 21a instead of in elongated slots. Thus, there is no need for an anchor pin 26 and tensioning spring 25 as used with clamp 17. Since the jaws, key, and keyway of stationary clamp 16 are similar to those previously described for clamp 17, no further description of these elements will be given.

In operation, the operating pins 24 of clamps l6 and 17 are forced inward towards movable jaw 36 by manually pushing on the end portions 24a of the pins which protrude from the sides of the clamps thereby causing the jaws to open and compress springs 39. The operating pin of adjustable clamp 17 is also shifted within elongated slots 22 and 23 towards the stationary clamp 16 and against the restraining action of spring 25. A flexible pouch is then inserted between the open jaws 31 and 36 of the clamps and the operating pins are released. The springs 39 and 25 thus return to their normal conditions and the side edges of the flexible containers are gripped between the key and keyway ofjaws 31 and 36 while tension spring 25 applies a tensioning force across the upper portion of the flexible container so as to provide a one way valve therein.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What is claimed is:

1. A clamp for anchoring an edge of a thin flexible article against a tension force tending to withdraw the article from the clamp, said clamp comprising a first jaw; a key formed of resilient material mounted upon said first jaw; a second jaw formed of rigid material and having a keyway therein with a substantially rectangular cross-section adapted to receive the key on said first jaw, said second jaw having a face opposite said first jaw and a keyway side face substantially perpendicular thereto with a corner therebetween; said key having a generally circular crosssection with a diameter greater than the depth of the keyway; and means connecting said first and second jaws for movement of at least one jaw relative to the other jaw between an open jaw position and a closed jaw position; whereby the edge of the flexible article can be inserted between said jaws in their open position and upon closing of the jaws will be bent around the corner between the second jaw face and the keyway side face so that the second jaw resists a tension force imposed on the flexible article, whereby the edge of the flexible article is bent to conform with the configuration defined between the key and keyway so that it must be drawn through a restricted passage with a series of bends therein to be withdrawn from between the jaws in their closed position, and whereby the flexible article edge is gripped between the key and the bottom of the keyway.

2. A clamp as described in claim ll wherein said key is mounted so as to be able to be deformed slightly in response to lateral forces for gripping the edge of the flexible article upon said keyway side face.

3. A clamp as described in claim 2 wherein said key is an annular member fitting around said first jaw and being retained within grooves located at opposite edges of the first jaw.

4. A clamp for anchoring an edge of a thin flexible article against a tension force tending to withdraw the article from the clamp, said clamp comprising a first jaw; a key formed of resilient material mounted upon said first jaw; a second jaw formed of rigid material and having a keyway therein adapted to receive the key on said first jaw; and means connecting said first and second jaws for movement of at least one jaw relative to the other jaw between an open jaw position and a closed jaw position; said jaw connecting means including an operating pin slidably fitted through each jaw but having a stepped radial face to retain one jaw at a given axial position on the pin, a pair of side plates supporting the ends of the pin, and a spring fitting around the pin between one side plate and one of said jaws to urge said one jaw into engagement with the stepped radial face of the pin and said otherjaw; whereby said pin can be shifted axially to compress the spring to open the jaws and, upon release of the shifting force, will be resiliently returned to a closed jaw position by the spring; and whereby the edge of the flexible article can be inserted between the jaws, in their open position and upon closing of the jaws will be bent to conform to the configuration defined between the key and keyway so that the edge of the flexible article must be drawn through a restricted passage with a series of bends therein in order to be withdrawn from between the jaws in their closed position.

5. A clamp as described in claim 4 wherein said pin is supported within slots within the pair of side plates, and further including a spring urging the pin towards one end of the slots.

Claims (5)

1. A clamp for anchoring an edge of a thin flexible article against a tension force tending to withdraw the article from the clamp, said clamp comprising a first jaw; a key formed of resilient material mounted upon said first jaw; a second jaw formed of rigid material and having a keyway therein with a substantially rectangular cross-section adapted to receive the key on said first jaw, said second jaw having a face opposite said first jaw and a keyway side face substantially perpendicular thereto with a corner therebetween; said key having a generally circular cross-section with a diameter greater than the depth of the keyway; and means connecting said first and second jaws for movement of at least one jaw relative to the other jaw between an open jaw position and a closed jaw position; whereby the edge of the flexible article can be inserted between said jaws in their open position and upon closing of the jaws will be bent around the corner between the second jaw face and the keyway side face so that the second jaw resists a tension force imposed on the flexible article, whereby the edge of the flexible article is bent to conform with the configuration defined between the key and keyway so that it must be drawn through a restricted passage with a series of bends therein to be withdrawn from between the jaws in their closed position, and whereby the flexible article edge is gripped between the key and the bottom of the keyway.

2. A clamp as described in claim 1 wherein said key is mounted so as to be able to be deformed slightly in response to lateral forces for gripping the edge of the flexible article upon said keyway side face.

3. A clamp as described in claim 2 wherein said key is an annular member fitting around said first jaw and being retained within grooves located at opposite edges of the first jaw.

4. A clamp for anchoring an edge of a thin flexible article against a tension force tending to withdraw the article from the clamp, said clamp comprising a first jaw; a key formed of resilient material mounted upon said first jaw; a second jaw formed of rigid material and having a keyway therein adapted to receive the key on said first jaw; and means connecting said first and second jaws for mOvement of at least one jaw relative to the other jaw between an open jaw position and a closed jaw position; said jaw connecting means including an operating pin slidably fitted through each jaw but having a stepped radial face to retain one jaw at a given axial position on the pin, a pair of side plates supporting the ends of the pin, and a spring fitting around the pin between one side plate and one of said jaws to urge said one jaw into engagement with the stepped radial face of the pin and said other jaw; whereby said pin can be shifted axially to compress the spring to open the jaws and, upon release of the shifting force, will be resiliently returned to a closed jaw position by the spring; and whereby the edge of the flexible article can be inserted between the jaws in their open position and upon closing of the jaws will be bent to conform to the configuration defined between the key and keyway so that the edge of the flexible article must be drawn through a restricted passage with a series of bends therein in order to be withdrawn from between the jaws in their closed position.

5. A clamp as described in claim 4 wherein said pin is supported within slots within the pair of side plates, and further including a spring urging the pin towards one end of the slots.

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