Abstract: A tooth-profile shaped spline convenient to rotary elements of a multi spindle extruder is provided. The spline has a tooth profile which can be provided by deforming a continuous curve as if the x-axis ran on a center circle of predetermined radius. This continuous curve before deformation is a continuous line obtained by connecting a semi-circular or semi-oval line, the line being represented by an expression of x.sup.2 /a.sup.2 +y.sup.2 /b.sup.2 =1 in a defined area of y.gtoreq.0, with another semi-circular or semi-oval line, the another line being represented by the expression of x.sup.2 /a.sup.2 +y.sup.2 /b.sup.2 =1 in a defined area of y.ltoreq.0, by turns.

Abstract: An apparatus for controlling a heating temperature, especially for heating a resin in a injection mold machine, a extruder and the like, includes a control device for controlling a heating means and the state of a heated barrel and a condition compensating device for issuing a compensation input to the heaters respectively in response to a reset of the control device, depending on the kinds of resin materials and molding conditions so as to prevent insufficient moldability in the injection mold machine and a deterioration of resin.

Abstract: Relative displacement of parts of a machine tool caused by thermal deformation is compensatively corrected for by a correction system comprising a diffused light source mounted near the main spindle of the machine tool for holding a machining tool, a lens mounted apart from the light source on the table which is moveable relative to the main spindle and functions to hold a workpiece, a light spot displacement detector for detecting variation of position of a light source image formed by the lens and generating a corresponding detection signal, and a control means operating to compute, from this signal, any relative displacement of the table and the light source and, on the basis of this relative displacement, to correct the relative position of the table and the main spindle.