Howa Machinery, Ltd.

Yoshiaki Mase

Tetsuya Oketani

Yukihiro Sakakibara

Hirotaka Nishikawa

Norimitsu Araki

Toshio Ito

Tools are classified into small type tools that can pass through the space between a pair of grippers in its open position and large type tools that cannot pass through the space between the pair of grippers in the open position, when the headstock supporting a spindle holding a tool is moved to a position corresponding to a tool change position. When the next tool to be used is of the small type, the tool is moved through a standby position to the tool change position during a machining operation using the tool on the spindle, the headstock is moved to the position corresponding to the tool change position in response to a tool changing instruction and a predetermined tool changing operation is carried out. When the next tool is of the large type, the next tool is positioned and held at the standby position during a machining operation, the headstock is moved to the position corresponding to the tool change position, the next tool is moved to the tool change position and the tool changing operation is carried out.

Tool changing method and apparatus

A tool magazine disclosed is fundamentally the same in construction as a corresponding prior art tool magazine but is capable of handling tools of diameters greater than those of tools which can be handled by the prior art tool magazine. The tool magazine comprise a magazine body provided with an endless guide groove, and a plurality of tool pots each for holding a tool, fixedly provided with guide members engaging the endless guide groove for sliding movement along the guide groove. Idlers are disposed between and in contact with adjacent tool pots, respectively, and supported in the endless guide groove so as to move along the endless guide groove. A feed mechanism moves the tool pots and the idlers along the endless guide groove with the idlers in contact with the guide members of the adjacent tool pots, respectively. The idlers are substantially the same in shape and dimensions as the guide members. The surface of each guide member is coated with an abrasion-resistant film having a small coefficient of dynamic friction.

Tool magazine for machine tool

A toolholder device for a machine tool comprises a holder body driven by a machine tool drive spindle, and a toolholder supported on the holder body so as to be circumferentially and axially displaceable. The holder body and the toolholder are provided with displacement detection elements which are arranged circumferentially in interdigitating relation. A support shaft extends from either member of the holder body and the toolholder toward the other member. The outer surface of the support shaft and the inner surface of a support hole of the other member to be fitted over the support shaft are formed with helical guide grooves which are opposite to each other and slopingly extends with respect to the rotational axis of the toolholder device. Balls are interposed between the opposite guide grooves to form a displacement translation mechanism which converts a rearward axial displacement of a tool and the toolholder due to overload axial thrust into a circumferential relative displacement between the adjacent detection elements. The relative displacement of the detection elements is detected by a detection unit which issues a warning signal. A compression spring in the device resists the axial displacement of the toolholder unless the axial thrust exceeds a predetermined value.

Toolholder device for machine tools

A toolholder assembly is divided into a drive toolholder coupled to the drive spindle of a machine tool, and a driven toolholder carrying a cutting tool such as a drill. The driven toolholder is coupled end to end to a drive toolholder so as to be rotatable relative to the same through a preassigned angle about the toolholder axis. A coiled torsion spring acts between the drive and the driven toolholders for torque transmission from the former to the latter. The drive and the driven toolholders have interdigitating teeth with clearances therebetween. A phase detector such as a proximity switch detects a relative phase displacement that will occur between the interdigitating teeth against the force of the torsion spring upon development of abnormal torque load on the cutting tool. Preferably, the interdigitating teeth have bevels in sliding engagement with each other for causing a relative phase displacement between the teeth upon axial displacement of the driven toolholder toward the drive toolholder, so that not only abnormal torque load but also abnormal thrust load on the cutting tool is detectable by the phase detector.

Torque and thrust overload detection system for a machine tool

An indexing apparatus for a rotary table has a support shaft rotatably supported by a base member in which indexed terminal positions of the rotary table is determined by abutment of a stopper member provided on the rotary table against positioning members provided on the base member. The indexing apparatus comprises a rack-pinion mechanism comprising a rack and a pinion fixed around the support shaft of the rotary table for rotating the same, a feed screw shaft rotatably supported by the base member and extending along the rack in a direction of the movement thereof, a breakable electric motor for driving the feed screw shaft, and a feed nut engaging the feed screw shaft. The rack and the feed nut are arranged so that either one of them has integral portions disposed at both sides of the other with spaces left on both the sides in the direction of the movement of the rack. Annular springs are disposed in each space. As the rotary indexing operation approaches the terminal position, the spring is elastically deformed in the direction of the movement of the rack so that shocks due to the abutting are prevented. Immediately before the indexed terminal positions, the speed of the motor is reduced and then the motor is braked.

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Gifu, Japan

Yoshiaki Mase