Pliers for crimping work pieces

Details Pliers for crimping work pieces Pliers for crimping work pieces

2000-05-24

2001-09-18

Crane, Daniel C. (Department: 3725)

Metal deforming

With means to actuate both elements of tool-couple

Handle actuated

C072S409010, C072S416000, C072S409120

Reexamination Certificate

active

06289712

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of co-pending German Patent Application No. 199 24 087.6-15 entitled “Zange zum Verpressen von Fassungen, Rohren, Kabelschuhen und dgl.” filed on May 26, 1999.
FIELD OF THE INVENTION
The present invention generally relates to pliers for crimping work pieces. More particularly, the present invention relates to pliers including plates and being operable with one hand.
BACKGROUND OF THE INVENTION
Such pliers 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 are no or 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. To pivot jaws are supported by a joint. One of the 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 serves to reach a defined end position of the separated dies. A pressure lever is arranged between the handles, and it is pivotable by the supporting joint. The pressure lever together with a section of the movable handle forms a toggle lever drive. The two dies and the corresponding pivot jaws are designed as one piece. They are produced by precision casting. The fixed connection of the combined pivot jaw/die to the stationary handle is disadvantageous. 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, in many cases it is necessary to rework the pliers. The known pliers include handles made of molded plastic. These handles bring a great stability at a reduced exactness. Since the material flows, disadvantageous displacements of prearrange bores cannot be prevented.
Pliers for producing solderless connections between current conduits and corresponding connection elements by crimping the work pieces are known from German Auslegeschrift DE-AS 21 49 167. The pliers have a plate design, and they provide the corresponding advantages. The rather simple and exact production of the plates, for example by punching, is advantageous.
Linearly driven pliers having a plate design are known from German patent 34 11 397 C2. The necessary forces for producing solderless connections are not substantial.
SUMMARY OF THE INVENTION
Briefly described, the present invention provides pliers for crimping work pieces. The pliers include a first stationary handle and a second movable handle. The first and second handle are designed and arranged to be movable with respect to one another and to be operable by one hand. A first pivot jaw is connected to the first stationary handle to form a stationary pliers portion. A second pivot jaw is connected to the second movable handle. The first and second pivot jaw each includes at least two parallel plates extending symmetrically to a plane of main extension of the pliers. A common joint pivotally connects the stationary pliers portion and the second pivot jaw. A first die is designed as a semi shell and to be insertable into the first pivot jaw. A second die is designed as a semi shell and to be insertable into the second pivot jaw. The first and second die together form a crimping die, and they are designed and arranged to contact one another in a closed position of the pliers in a separation plane. At least one of the semi shells is arranged at the corresponding pivot jaw with a clearance to be movable in the separation plane in the sense of a centering adjustment of the semi shells.
The present invention is based on the concept of designing the pliers user friendly and 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 be grasped by the fingers of one hand of the user even in the opened position of the pliers. On the other hand, producing tolerances should be kept as small as possible. A plate design of the pliers is especially suitable for attaining small producing tolerances. The plate design also makes it possible to better introduce and distribute the pressing forces in the dies and in the semi shells, respectively. The use of semi shells allows for a great exactness and easy manufacture, for example by turning on a lathe. Additionally, the roundness of the crimped work piece is improved. The clearance allowing for a centering movement in the direction of the separation area of the dies has a positive effect. There is an automatic centering movement when the work piece is crimped. The clearance also makes it possible to easily remove and replace the semi shells. With the novel pliers, it is possible to apply great crimping forces, as they are necessary for plastically deforming the work piece. This is achieved by a one-hand operation and even in case of undesired working conditions. The short structural length and the low weight of the pliers allow for a one-hand operation. The pliers include a locking mechanism locking in at an early time such that the pliers cannot leave a half opened position by themselves. During the actual crimping action, it is possible to put both hands around the already approached handles to produce a crimping force being sufficient to plastically deform metals. The pliers are also handy in case of tight working conditions, and they may be opened in the region of the dies fairly wide without losing the possibility of operating the pliers by one hand.
The locking mechanism is arranged between the stationary handle and the pivot jaw being pivotable by a joint. The locking mechanism is of great importance to the pliers. The jack of the locking mechanism is resiliently movable but stationary, and it may be arranged at the stationary handle. The locking mechanism should include a tooth segment including a majority of teeth. The tooth segment is arranged on the movable pivot jaw, or it is at least connected thereto. The pliers may be adjusted in a way that the closing position is reliably attained, and that a great crimping pressure is reproducibly applied before the pliers may be reopened, or before they are reopened by a spring.
In a preferred embodiment of the pliers, both pivot jaws include three plates, the center plate of which is arranged in the plane of main extension of the pliers. The center plate together with the two other plates being arranged symmetrically with respect to the plane of main extension of pliers allows for an introduction of force into the dies being designed as semi shells. Additionally, crimping forces are introduced into the semi shells in a spaced apart manner to advantageously have an effect along at the length of the semi shells.
The center plate of each pivot jaw may be pivotable with respect to the other plates to replace the dies. Thus, the center plate fulfills a further function. The semi shells at their other circumference include a continuous channel being centeringly engaged by the center plates.
The plates of each pivot jaw may be interconnected by an additional securing pin. Such a securing pin or bolt is not absolutely necessary for a pivotal movement. Nevertheless, it has a positive effe

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