US 3906957 A
Forceps, either of the tweezer type or scissors-like type, in which cross-beaking of the jaws is resisted by the presence of a flexible connector attached between the forceps arms adjacent to the jaws. This connector is bowed away from the jaws and extends sufficiently in a plane at right angles to the plane of movement of the arms at the points of attachment to the arms to resist torsion during the operation of the forceps.
Description (OCR text may contain errors)
"United States Patent [1 1 Weston I Sept. 23, 1975  FORCEPS 2,199,685 5/1940 Wood 128/354 3,367,336 2/1968 E' b 128/354 X  Inventor: David Frederick Weston, Runcorn, 3,636,954 H1972 75: 128/321 England 3,653,389 4/1972 Shannon v l 128/354  Assigneez Imperial Chemical Industries 3,817,078 6/1974 Reed et al 128/354 X Limited, London, England FOREIGN PATENTS 0 R APPLICATIONS  Filed: Mar. 11, 1974 880,990 1/19'43 France 81/43 2 l. 1 1] App NO 450195 Primary Examiner-Channing L. Pace Attorney, Agent, or Firm-Cushman, Darby &  Foreign Application Priority Data Cushman Apr. 24, 1973 United Kingdom 19278/73 Nov. 14, 1973 United Kingdom 52875/73  ABSTRACT Forceps, either of the tweezer type or scissors-like  US. Cl. 128/321, 24/255 TZl,2881//3453A yp in which Crossbeaking of the j is resisted by Int Cl 2 A6113 l7/28 A61B 17/00 B25B 9/02 the presence of a flexible connector attached between Fieid Search 247255 81/4} 128/32l the forceps arms adjacent to the jaws. This connector l28/354 248/226 E 316 is bowed away from the jaws and extends sufficiently in a plane at right angles to the plane of movement of References Cited the arms at the points of attachment to the arms to re- UNITED STATES PATENTS 1,714,822 5/1929 Segal 81/43 X sist torsion during the operation of the forceps.
6 Claims, 4 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of 2 3,906,957
US Patent Sept. 23,1975
re EWM Sheet 2 of 2 FORCEPS This invention relates to forceps, that is gripping instruments either in the form of dissecting forceps or tweezers, or in the form of scissors-like devices.
Conventional dissecting forceps or tweezers are formed from a pair of substantially rigid arms, each terminating in a jaw, connected at the end remote from the jaw by a resilient flexible member which serves to space the arms apart by about l and acts as a fulcrum about which the arms can rotate. Compression of the arms causes the jaws to come together for the purpose of gripping an object, and on release of the compression forces, the resilience of the connecting member causes the jaws to open.
In a scissors-like device, the arms are operated by levers located on the opposite side of the fulcrum to the jaws, and in consequence it is not necessary for the connecting member to be resilient, although this is not excluded.
A common feature of both types of forceps is the presence of elongated arms with the jaws located remote from the fulcrum of the forceps. Accordingly, there is a tendency for the jaws to cross-beak in operation, and especially with tweezers, it is usual to provide a pin and socket arrangement between the arms and adjacent to the jaws to maintain the alignment of the jaws. If the forceps are made of plastics material, the tendency for the jaws to cross-beak is greater than if the forceps are made of metal, and the provision of a pin and socket is less convenient. The present invention concerns an alternative method of reducing the tendency of forceps to cross-beak, particularly plastics forceps, by providing a second connector between the arms near to the jaws.
According to the invention there is provided forceps including a pair of arms, each arm having a jaw at one end and the arms being joined to each other at the other end by an intermediate section, and means for aligning the jaws in the form of a flexible member attached between the two arms at points adjacent to the jaws, bowed away from the jaws, and extending in a plane normal to that of movement of the arms at the points of attachment to the arms.
When the forceps is in the form of tweezers, it is desirable that the arms be operating arms normally spaced apart, and the arms, intermediate section and flexible member together form a resilient structure which allows the jaws to be closed by compression of the operating arms and opened by release of the compression.
By the term normally spaced apart is meant that the jaws are in the open position when the forceps are not stressed, that is when no compression is applied to the forceps. The intermediate section may have a uniform cross-section or it may incorporate a portion 'of narrower cross-section.
When the forceps is in the form of a scissors-like device, a similar resilient structure may be formed, but since the intermediate section may be a pivot pin or a web of material acting as a fulcrum, it is not necessary that a resilient structure be formed. The forceps in this latter form will of course include operating levers which may be extensions of the arms or distinct levers attached by flexible webs to the arms, as for example illustrated in U.K. Patent Specification No. 1,253,526.
The nearer the flexible member is located to the jaws, the greater is its effect in resisting cross-beaking of the jaws, but clearly a sufficient distance must be provided between the jaws and the flexible member to permit the forceps to grip the articles which are intendedto be gripped by them. Similarly, the greater the distance the flexible member extends normal to the plane of movement of the arms, the greater is its effectin resisting cross-beaking of the jaws, and while a convenient maximum such extension is a distance equal to the width of the operating arms in that direction, the flexible member may extend a shortersuch distance. However, if the flexiblemember does not extend a uniform distance normal'to the plane of movement of the arms, then the minimum such distance must be sufficient to resist torsion, of the flexible member. I
Since the arms, intermediate section and flexible member may together form a resilient structure, it is possible for this resilience to be due principally to the resilience of the intermediate section, the flexible member or the arms or any combination of these parts. In a preferred embodiment, the flexible member is less resilient than the structure formed by the arms and intermediate section and so the force required to operate the forceps is not unduly increased over that required to compress the arms and intermediate section.
When the forceps is in the form of a scissors-like device, there is no need for the flexible member to be resilient although this is not excluded. I
The flexible member may be a strip of material of uniform cross section which bows when the forceps are used, but a preferred flexible member includes at least one narrow section which acts as a hinge. A flexible member attached to each arm by such a hinge and also having an intermediate hinge is particularly preferred.
In order that the invention may be more clearly understood, two preferred embodiments of the forceps will now be described, by way of example only, with reference to the accompanying drawings of which:
FIG. I is a vertical elevation of one embodiment of the forceps in the unstressed condition,
' FIG. II is a perspective view of the embodiment shown in FIG. I,
FIG. III is a vertical elevation of a second embodiment of the forceps in the closed position,
and FIG. IV is a view of the embodiment of FIG. III
in the open position.
The forceps of the invention illustrated in FIGS. I and II is in the form of dissecting forceps or tweezers in plastics material shaped to provide a pair of operating arms 1 and 2 joined together end to end at an angle of about 15 by an intermediate section 3. In the embodiment illustrated, the arms 1 and 2 and the section 3 are integral and of the same cross section, and the structure formed by the arms 1, land section 3 is resilient by reason of the nature of the plastics material employed. At the ends of each arm 1 and 2 remote from section 3 is a jaw member 4 or 5. Each arm is provided with a gripping surface 6 on its outer surface and is strengthened by a ridge 7 along its inner surface. Between the arms 1 and 2 and adjacent to the jaws 4 and 5 is a flexible member attached to the inner surface of each arm. The flexible member is in the form of two rectangular, substantially rigid plates 8 and 9 joined along one edge by a thin web of material 10. The plate 8 is joined to arm 1 by a thin web of material 11 along the opposite edge to that bearing web 10 and the plate 9 is joined to arm 2 by another thin web of material 12 along the opposite edge to that bearing web 10. Each of the webs l0, l1 and 12 can act as a hinge. The plates 8 and 9 are located in a plane normal to the plane of movement of the arms 1, 2 at the points 11, 12 of attachment of the plates 8, 9 to the arms, and the width (FIG. II) of the plates in this plane is equal to the width of the arms 1 and 2 in this plane. The length of the plates 8 and 9 taken together is greater than the distance between their points of attachment on arms 1 and 2 when the forceps is unstressed and the web 10 between the plates 8 and 9 is displaced away from the jaws 4 and 5. The flexible member as a whole is thus bowed away from the jaws 4 and 5.
In operation when it is desired to use the forceps to grip an object, the forceps is taken in one hand with the thumb on one gripping surface 6 and the forefinger on the other gripping surface 6. The jaws 4 and are placed across the object to be gripped and the arms 1 and 2 are compressed. The resilient structure formed from arms 1 and 2 together with section 3 is deformed as the jaws 4 and 5 come towards each other and the flexible member, being less resilient than the arms 1 and 2 with section 3, is readily bowed further away from the jaws 4 and 5 by bending about webs 10, 11 and 12. Since the webs 11 and 12 extend across the width of arms 1 and 2 respectively, relatively close to the jaws 4 and 5, any tendency for the jaws 4 and 5 to move out of alignment in their plane of movement as a result of torsion in the section 3 is resisted by the flexible member. When the object gripped is to be released, the compression on arms 1 and 2 is relaxed and the resilience of the structure formed from arms 1 and 2 and section 3 causes the jaws to open and release the object.
The forceps of the invention illustrated in FIGS. III and IV is in the form ofa scissors-like device in a single piece of plastics material shaped to provide a pair of arms 1 and 2, withjaws 4 and 5,joined by an intermediate section in the form of a web 3 which acts as a fulcrum, and a pair of operating levers 13 and 14 attached to the arms 1 and 2 by webs l5 and 16 respectively and to each other by a web 17. The four webs 3, 15, 16 and 17 are situated in a diamond configuration. Attached to each arm 1 and 2 at a point approximately midway between the jaws 4 and 5 and the web 3 is a flexible member in the form of two rectangular plates 8 and 9 hinged by a web 10 and attached to the inner surface of the arms 1 and 2 by webs 11 and 12 in the same way as described for the embodiment shown in FIGS. I and II. Although not illustrated, the webs 11 and 12 extend across the full width of the inner surface of the arms 1 and 2 respectively, and as illustrated (FIG. IV) the length of plates 8 and 9 taken together is greater than the distance between their points of attachment when the forceps is in the open position. The forceps of FIGS. III and IV is shaped so that when the forceps are closed (FIG. III), the web 17 joining the operating levers l3 and 14 passes across the line joining webs l5 and 16 thus making the forceps self-locking. Such a structure is described and claimed in our co-pending application No. 18632/72.
In operation, the plates 8 and 9, together with the webs 10, 11 and 12 act in the same way as in the embodiment of FIGS. I and II to resist any tendency of the 5 jaws 4 and 5 to move out of alignment.
The above described forceps are made from plastics material, but the principle of the invention may be applied to forceps made from any other material, for example metal. However the present design of forceps is particularly advantageous when applied to forceps made from plastics material since the problem of crossbeaking is greatest with plastics forceps and the present design can be manufactured by one shot injection moulding from any thermoplastic material. The forceps can thus be made cheaply enough to be a disposable item. Preferred plastics materials from which the forceps of the invention can be manufactured are,-thermoplastic polymers, for example polypropylene, polyethylene, nylon, polyesters, for example polyethylene terephthalate, or polystyrene, or any of these materials together with a filler, for example talc or glass fibre. A preferred material is talc filled polypropylene.
In the two embodiments illustrated, the jaws 4, 5 are shown as simple pliers-like jaws with transverse teeth. However, the invention can be applied to forceps provided with any type of jaw, pointed, spatulate or curved, and provided with any type of gripping surface or indeed lacking such a surface, if appropriate to the use.
What we claim is:
1. Forceps comprising a. a pair of arms each having a first and a second end,
b. a jaw located at the first end of each arm,
c. an intermediate section joining the second ends of each arm remote from said jaws for permitting relative movement of said arms in a plane passing through the length of each arm, and
d. flexible connector means attached between the two said arms at points adjacent said jaws, being bowed away from said jaws toward said intermediate section and moving in the space between said arms about said points of attachment.
2. Forceps as claimed in claim 1 wherein the flexible connector means comprises two plates joined together along one edge by a web acting as a hinge and attached to the arms along opposite edges by webs acting as hinges.
3. Forceps as claimed in claim 1 in the form of tweezers in which the arms are operating arms normally spaced apart, and the arms, intermediate section and flexible connector means together form a resilient structure.
4. Forceps as claimed in claim 1 in the form of a scissors-like device additionally comprising operating levers for moving the arms.
5. Forceps as claimed in claim 4 wherein the operating levers are attached to each other and to the arms by flexible webs.
6. Forceps as claimed in claim 1 formed in a single piece of plastics material.
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