Arrangement for controlling the advancing device of a machine for repetitive operations

In an arrangement for controlling an advancing device of a machine for repetitive operations, especially for controlling movement of a slide carrying a cutting device of a cutting machine for cutting an elongated workpiece such as a profile emanating at a predetermined speed from a profiling machine, an extrusion press, a straightening machine or the like into sections of uniform length, a combination comprising means for moving the slide in the direction of the moving workpiece and comprising fluid-operated means including a cylinder member and a piston member reciprocatably arranged in said cylinder member and dividing the latter in two compartments, one of said members being stationary and the other fixed to the slide;

• a circuit for hydraulic pressure fluid;
• main valve means in said hydraulic pressure fluid circuit for controlling flow of pressure fluid into and out of the respective compartments;
• an abutment on the slide located in the path of the front end of the advancing workpiece;
• switch means on the slide upstream of said abutment, as considered in the direction of the moving workpiece, to be actuated as the front end of the workpiece passes said switch means;
• means in circuit with said switch means and cooperating with said moving means for preaccelerating said slide upon actuating said switch means to a speed smaller than the predetermined speed and comprising auxiliary valve means controlled by said switch means and preaccelerating cylinder and piston means controlled by said auxiliary valve means and cooperating with said main valve means for controlling flow of pressure fluid into and out of the compartments to thus preaccelerate the slide to a speed smaller than said predetermined speed;
• and means operatively connected to said abutment and said main valve means for controlling flow of pressure fluid into and out of the compartments in such a manner that upon an engagement of the front end of the workpiece with said abutment said slide is accelerated to said predetermined speed.