It is known to provide a pre-stressed frame for a hydraulic press in which the frame has two opposed cross-heads with thrust members spacing the cross-heads apart and traction members drawing the cross-heads against the thrust members and thus pre-stressing the frame. There is provided a simpler construction which is easier to manufacture, and which is not so susceptible to notch stresses, by having the traction members in the form of plates.
There is a known prestressed press frame formed by a cylinder cross-member and a counter cross-member of the press and also at least two columns between the cylinder and counter cross-members each column being defined by a stack of sheet metal laminations in tension and a hollow rectangular support member in compression and surrounding the laminations. According to the invention, the perpendicular to the centers of the faces or broad sides of the laminations or plates and to the centers of those walls of the support members which are parallel to the faces or broad sides of the laminations, intersect the press axis.
A single-level or multilevel or continuous board press is composed of a succession of press frames which are subdivided horizontally at their vertical limbs for transport and when then welded together at the erection site. Leveling strips are provided along mounted surfaces of the frame to support the plates, piston-and-cylinder units and the like serving to press the mats of wood material.
A press is provided for forming articles from compressed refractory material such as bricks, the press including a press bed, a crown spaced from the press bed, and a plurality of prestressed support columns rigidly supporting the press bed and the crown in spaced apart relation. The support columns each include a central tie rod including one end extending through a portion of the press bed and including another end extending through a portion of the crown and rigidly engaging the crown. The support columns also include an outer hollow cylindrical member surrounding the tie rods, one end of each of the hollow cylindrical members being positioned against the upper surface of the bed and the opposite end of each of the hollow cylindrical members engaging a lower portion of the crown. The tie rods are subjected to a tensile force while the outer cylindrical members are simultaneously subjected to a compressive force thereby providing a rigid frame structure and one resistive to twisting. The outer cylindrical members also function to provide supporting columns for a mold table and provide for slidable movement of the mold table between the bed and the yoke. The outer cylindrical members also provide for slidable support of a movable crosshead and facilitate movement of the crosshead toward and away from the mold table.
The present invention relates to a pre-stressed tie rod and method of manufacture. The pre-stressed tie rod can be used on injection molding machines to increase the length of the tie rod and movement of the platen, wherein the tie rods are loaded to restrict mold separation. The pre-stressed tie rods could also be used with other types of presses.
A platen design is provided for a C-frame press whereby an un-stiffened platen column connected in series to the tie rod; therefore, the stiffness of the tie rod is reduced. The unique design improves the fatigue strength of the tie rod by moving the reinforcing webs away from the column and directly onto the platen main body portion.
