Metal deforming – With means to actuate both elements of tool-couple – Handle actuated
Reexamination Certificate
2000-12-18
2002-11-05
Crane, Daniel C. (Department: 3725)
Metal deforming
With means to actuate both elements of tool-couple
Handle actuated
C072S409120, C081S313000, C081S393000
Reexamination Certificate
active
06474130
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of co-pending German Patent Application No. 199 63 097.6 entitled “Zange zum Verpressen eines Werkstüicks” filed on Dec. 24, 1999.
FIELD OF THE INVENTION
The present invention generally relates to pliers for crimping work pieces. More particularly, the present invention relates to pliers being operable with one hand and serving to apply great crimping forces onto the work piece in a few crimping steps.
BACKGROUND OF THE INVENTION
Pliers of this kind are also called crimping pliers or pressing pliers. Depending on the design of the work piece, especially in case of fittings, tubes and the like to be crimped, substantial pressing forces have to be applied onto the work piece. On the other hand, such work pieces may have comparatively great dimensions. Consequently, the crimping die being formed by two dies should have a great opening in the opened position of the pliers to be able to move the two dies over the work piece to be crimped in the opened position of the pliers. At the beginning of the closing movement of the pliers, there usually are no or at least no substantial pressing forces to be overcome. Contrarily, the pressing forces to be applied during the actual crimping movement of the work piece are substantial.
Pliers for crimping work pieces are known from German patent application DE 197 09 639 A1. The pliers include two handles being movable with respect to one another by one hand. A joint supports two pivot jaws. One of the two pivot jaws is connected to a stationary handle to form a stationary portion of the pliers. The other pivot jaw is pivotally connected to the stationary portion of the pliers by the joint. The pliers include separated dies forming a crimping die. A locking mechanism is arranged between the stationary handle and the movable handle, and it serves to reach a defined end position of the separated dies. The handles may first be reopened after one crimping process has been finished, after the end position has been reached and after the locking mechanism has released the handles. A pressure lever is arranged between the handles, and it is pivotally supported by the supporting joint. The pressure lever together with a section of the movable handle forms a toggle lever drive. This sole pressure lever is supported in a supporting joint including an eccentric surface allowing for an adjustment of the effective length of the pressure lever. The adjustability of the pressure lever serves to compensate work tolerances to exactly associative a closing position of the handles with an end crimping position of the pliers. It is also possible to adjust the pressure lever to eliminate wear and tear occurring at the connected joints or the dies. The two dies and the corresponding pivot jaws are designed as one piece. The fixed connection of the combined pivot jaw/die to the stationary handle is disadvantageous. The maximum applicable crimping forces are limited. Additionally, the preciseness of the finished crimped work piece highly depends on the realizable process tolerances with which the elements of the pliers are produced and which are used to assemble the pliers. Consequently, it is necessary to rework the dies of the pliers in many cases. The known pliers include handles made of molded plastic. These handles provide great stability at reduced exactness. Since the material flows, disadvantageous displacements of, for example, prearranged bores cannot be prevented. With the known pliers, the work piece is crimped in one crimping step.
Clamping pliers are known from German patent DE 25 59 656 B2. The clamping pliers include two handles being movable with respect to one another. Two pivot jaws are rotatable about a common joint. One of the pivot jaws is connected to a stationary handle to form a stationary pliers portion. The other pivot jaw is pivotally connected to the stationary pliers portion by the joint. A pressure lever is arranged between the two handles. The pressure lever is pivotal about a supporting joint and, together with a section of the stationary handle, it forms a toggle lever drive. To adjust the effective length of the pressure lever despite the fixed connection of the pressure lever at both ends at the handles, at least one of the supporting joints includes an eccentric tappet including different angle positions to adjust the kinematics of the clamping pliers, especially of the end position during the closing movement of the pivot jaws.
German patent DE 25 55 071 C2 additionally shows the application of a locking mechanism being arranged between the pressure lever and the stationary handle to reproducibly attain the defined end position of the pliers.
Clamping pliers including two handles being movable with respect to one another and two pivot jaws being pivotal about a common joint are known from U.S. Pat. No. 2,410,889. Each of the pivot jaws is connected to the associated handle to form a fixed pliers portion therewith. One of the two handles is divided into two portions each forming a lever to crimp the work piece in a few crimping steps. The two portions of the handle are interconnected by a joint to be pivotal with respect to one another. The portion of the handle to be held by the hand of the operator is lengthened in the direction towards the pliers head to extend beyond the joint to form a lever arm serving for transmission. A pulling lever is pivotally connected to the free end of the handle. The pulling lever encloses the two handles, and it is supported at the other handle not being divided. In this way, one portion of the divided handle is coupled to the other handle not being divided in each crimping step in different angle positions changing during the crimping process in a way that the end portions of the two handles facing away from the pliers head may be held and operated by the fingers of one hand in each angle position of each crimping step. Due to the division and support of the one handle at the other handle, there is an additional transmission of the actuation force to be applied by hand.
SUMMARY OF THE INVENTION
Briefly described, the present invention provides pliers for crimping work pieces. The pliers include a pliers head, a first pivot jaw being arranged in the region of the pliers head and a second pivot jaw being arranged in the region of the pliers head. A common joint pivotally connects the first and second pivot jaw. A first die is arranged at the first pivot jaw. A second die is arranged at the second pivot jaw. The first die and the second die together form a crimping die for crimping the work piece. A first handle is operatively connected to the first pivot jaw, and it includes an end portion facing away from the pliers head. The first handle is divided into at least a first portion and a second portion. A second handle is operatively connected to the second pivot jaw, and it includes an end portion facing away from the pliers head. The first and second handle are designed and arranged to be movable with respect to one another and to be operable to crimp the work piece in a few crimping steps. The second portion of the first handle is coupled to the first portion of the first handle in a plurality of different angle positions each corresponding to one crimping step in a way that the end portions of the first and second handle may be held and operated by the fingers of one hand of the operator in each angle position of each crimping step. A locking mechanism is designed and arranged to attain a defined closed position of the first and second die. A toggle lever drive includes a plurality of supporting joints and a pressure lever operatively connecting the first and second handle. The pressure lever is supported by the plurality of supporting joints.
The present invention is based on the concept of designing the pliers user friendly and appropriate for applying great crimping forces. It is desired to ensure that the pliers may be used and operated by one hand. This means that the handles need to be designed in a way that they may
Crane Daniel C.
Wezag GmbH Werkzeugfabrik
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