The subject invention is a self-centering vise designed for clamping workpieces with large dimensions and high cutting forces, for workpieces exposed to deformations, clamping logs, clamping workpieces with trapezoidal and rectangular cross-sections, of existing symmetry surface.

There are known self-centering vises, where power transmission is obtained by a turnbuckle, which rotary movement causes clamping/unclamping of the workpiece in a direction parallel to the axis of the turnbuckle. The control of clamping/unclamping is actuated with one square or hexagonal wrench at one of two ends of the turnbuckle. The advantage of this solution is a rigid design and ability to maintain high precision clamping. The disadvantage of this solution is a construction with a joint body for both jaws, which significantly reduces the clamping range of the vise, and its increase requires to create of a new design of substantial component parts (including body, and thus the largest part of the vise).

There are known modular vises, where clamping of the workpiece takes place at each pair of modules, equipped with a movable jaw, sliding T-handle screw or with additional knob/wrench. The rotary movement of the screw causes a linear traverse of the jaw along the guide, parallel to the screw axis. The modules in this solution are completely independent. The only possibility of their connection is a rigid link between their positions relative to each other. The advantage of this solution is the ability to obtain a substantial clamping range. The necessary condition to maintain the shape of the workpiece is a prior preparation of its shape. Otherwise, it may cause deformation of the long workpiece. The modular vises of this type can work in multi-units, however they are limited by the need of implementation of the joint base, and the principle of operation unable to link them to work simultaneously.

There are known modular vises, where clamping of the workpiece is divided into two phases - setting movement, obtained by moving the jaw manually along the guide body, and clamping movement, caused by the axial movement of the screw, which at the time of clamping is set in axis parallel to the direction of the jaw movement. According to this principle of operation it is not possible to link the clamping movements of the individual modules. There is also no possibility of self-centering or compensating clamping. The advantage of this solution is relatively high clamping repeatability and low time-consumption because of rapid idle stroke.

The matter of invention is a self-centering modular vise, where power transmission takes place via square wrench and additional self-centering compensating module. Drive of the jaw movement is perpendicular to the movement direction of jaw clamping/unclamping. A minimum of two independent modules are driven via centrally applied torque. The swiveling jaw inserts allow for vertical adjustment of the clamping surface to the clamped workpiece.

The advantage of the solution according to invention is a compact design that allows clamping in prisms without receiving degrees of freedom (compensation), while maintaining the position of the symmetry surface. Further advantages are: high clamping force obtained via gear drive ratio unit, self-locking drive unit that allows for wrench and self-centering module removal without force loss, possibility of simple extension of the system and increase of the clamping range and interchangeable jaws inserts that allow to adapt to specific shapes, including shaft-type components (without support) in prism inserts.

The subject of invention is shown in figure.

The components of a self-centering vise consist of: clamping jaw module 1, gear drive ratio unit 2, solid jaw 3, square wrench 4, swiveling jaw insert 5, interchangeable jaw insert 6, tension bar 7, drawbar 8, locking slot 9 and self-centering compensating module 10.

Torque from the square wrench on the linear gear, is transmitted to the toothed gear that cooperates with toothed bar, so-called gear rack. The rotary movement of the pinion is converted into sliding movement transmitted via gear rack carried out in leading channels, beyond self-centering compensating module, where via made hooks the force is transmitted linearly to tension bars, connected on the toothed side with pinions in the left and right clamping jaws. The jaws are an integral multi-unit parts of the gear drive ratio, that convert rotary movement of the pinion to linear movement of the solid jaws, directed towards the opposite jaw. The movement takes place until the maximum clamping force is obtained. The swinging insert ensures proper jaw alignment to the shape of the workpiece side walls. When using locking slot, the workpiece is clamped once it is set in driving axis on the symmetry surface of the clamped workpiece. When locking slot is removed the clamping takes place with compensation movement of the jaw, which as a first grips the workpiece. After clamping of the workpiece in clamping jaws the wrench movement in the direction opposite to clamping direction within a few degrees releases compensating self-centering module, that can be postponed. The force is maintained by self-locking drive multi-units. The wrench movement in a range of above-mentioned several degrees in direction opposite to clamping direction causes unclamping of the workpiece, and then outward moving of the jaws.