Abstract: The present invention provides an inexpensive chuck device that can achieve both a stable gripping operation and a high degree of accuracy in gripping and can also reduce limitations in the gripping of a workpiece. According to the present invention, a chuck device is provided, the chuck device being characterized by comprising a chuck main body and a master jaw, wherein the chuck main body has an oscillation supporting hole, and the oscillation supporting holes are rotatably provided in plurality around a rotational axis of the chuck main body, and wherein the master jaw has a top jaw detachably provided on one end thereof, and is fitted into the oscillation supporting hole while maintaining surface contact therewith to enable sliding contact.

Abstract: A chuck body is made up of axially movable plungers and jaws, in which the jaw has a master jaw body obliquely arranged with respect to an axis of the chuck body, the jaw also has a front face of the master jaw body and a rear end face of a master jaw head for restricting a position of the jaw with respect to the chuck body, a plunger receives a bushing which acts as a wedge means cooperating with the master jaw body, a driver at a rear end of the master jaw body being restricted in a backward movement within a range of a gap ?, and a wedge having a structure of canceling a moment applied to the jaw as a result of clamping, the driver providing a reactant force to the master jaw body for canceling a drawing force applied to a plunger.

Abstract: The invention has been developed to solve the drawbacks of the conventional chuck construction, and it is an object of the invention to provide a compact chuck construction, by omitting the axial movement parts, which are inevitable in the conventional chuck construction. A chuck body 10 comprising an axially movable plunger 30 and a jaw 20, in which said jaw 20 having master jaw body 24 obliquely arranged with respect to the axis, said plunger 30 having a bush 41 which act as a wedge, and a driving means 50 at the rear end of the master jaw body 24, said wedge means 40 having a structure of canceling a moment applied to the jaw 20 as a result of clamping and the driving means 50 providing a reactant force to the master jaw body 24 for canceling drawing force applied to the plunger 30.

Abstract: The present invention provides a method for producing .beta.-methylnaphthalene from an inexpensive and easily available feed oil. According to the invention, highly pure .beta.-methylnaphthalene adequate for industrial use can be mass-produced at reduced costs. The method comprises catalytic hydrodealkylation of a feed oil containing an alkyl naphthalene having at least two methyl groups in the presence of a catalyst having at least one metal species of selected from the group consisting of vanadium (V), chromium (Cr), nickel (Ni), rhodium (Rh), platinum (Pt), iridium (Ir), and compounds of these metals as an active component and a carrier therefor containing at least one of alumina and silica as its primary component, with a hydrogen partial pressure of 1 to 50 kgf/cm.sup.2, at a temperature of 450.degree. C. to 650.degree. C., and for a contact time of 3 to 35 seconds. The method of the invention is excellent in that it affords .beta.-methylnaphthalene of a chemical grade with a high yield.

Abstract: Catalytic hydrodealkylation by means of a catalyst which comprises microporous particles having a catalytic species carried thereon. Particulars of the microporous particles are disclosed.