Abstract: A main spindle device includes: a main spindle; a rod accommodated in the main spindle, the rod being capable of moving to an unclamp position in a direction toward the first end, and when the main spindle is holding a tool, being capable of moving to a clamp position in a direction toward a second end; a biasing unit that biases the rod in the direction toward the second end with respect to the main spindle and that biases the rod to the clamp position when a collet is holding the tool; and a biasing force detector that detects a biasing force of the biasing unit which biases the rod in the direction toward the second end after the rod is moved in the direction toward the first end with respect to the main spindle to the unclamp position by force larger than the biasing force of the biasing unit.

Abstract: A main spindle device includes: a main spindle; a rod accommodated in the main spindle, the rod being capable of moving to an unclamp position in a direction toward the first end, and when the main spindle is holding a tool, being capable of moving to a clamp position in a direction toward a second end; a biasing unit that biases the rod in the direction toward the second end with respect to the main spindle and that biases the rod to the clamp position when a collet is holding the tool; and a biasing force detector that detects a biasing force of the biasing unit which biases the rod in the direction toward the second end after the rod is moved in the direction toward the first end with respect to the main spindle to the unclamp position by force larger than the biasing force of the biasing unit.

Abstract: The damping property of a rear rolling bearing (133) is adjusted by controlling a damping force that is applied by damping application means (5, 134) based on, for example, the type of a tool (T). Thus, it is possible to provide the optimum damping properties for various tools that differ in natural vibration, and to suppress the generation of chattering of the various tools. As a result, it is possible to increase the cut amount per unit time to increase the productivity.

Abstract: By controlling an amount of preload applied to a rolling bearing that supports a spindle in accordance with the change of state of the spindle in actual machining, the rotation of the spindle is controlled in an optimal state, and the service life of the bearing is extended while the required stiffness of the spindle is ensured. When a corrected preload amount falls outside a range of a preload as a controllable region, the corrected preload amount is corrected so as to fall within the range of the preload. That is, an actually controlled preload is regulated to fall within the preset range of preload. Therefore, it is possible to ensure the stiffness of the rolling bearing or prevent heating and excessive increase in contact pressure of the rolling bearing.

Abstract: The damping property of a rear rolling bearing (133) is adjusted by controlling a damping force that is applied by damping application means (5, 134) based on, for example, the type of a tool (T). Thus, it is possible to provide the optimum damping properties for various tools that differ in natural vibration, and to suppress the generation of chattering of the various tools. As a result, it is possible to increase the cut amount per unit time to increase the productivity.

Abstract: By controlling an amount of preload applied to a rolling bearing that supports a spindle in accordance with the change of state of the spindle in actual machining, the rotation of the spindle is controlled in an optimal state, and the service life of the bearing is extended while the required stiffness of the spindle is ensured. When a corrected preload amount falls outside a range of a preload as a controllable region, the corrected preload amount is corrected so as to fall within the range of the preload. That is, an actually controlled preload is regulated to fall within the preset range of preload. Therefore, it is possible to ensure the stiffness of the rolling bearing or prevent heating and excessive increase in contact pressure of the rolling bearing.

Abstract: In order to detect accurately a seating of clamped body and a clamping force at a seating, the workpiece supporting device has plural seating mechanisms 40. Each of the seating mechanisms 40 includes a load sensing element 45 receiving a clamping force or a fixing force. The load sensing element 45 consists of a material having a characteristic that said load sensing element is not substantially deformed by an applied load, especially it consists of a composite material dispersing a material having a pressure resistance effect or a magnetic resistance effect in a matrix of an electric insulation ceramics material. An abnormal clamping or fixing of the clamped body and an abnormal overload are detected by detecting an output from plural load sensing elements 45 supporting the clamped body.

Abstract: In order to detect accurately a seating of clamped body and a clamping force at a seating, the workpiece supporting device has plural seating mechanisms 40. Each of the seating mechanisms 40 includes a load sensing element 45 receiving a clamping force or a fixing force. The load sensing element 45 consists of a material having a characteristic that said load sensing element is not substantially deformed by an applied load, especially it consists of a composite material dispersing a material having a pressure resistance effect or a magnetic resistance effect in a matrix of an electric insulation ceramics material. An abnormal clamping or fixing of the clamped body and an abnormal overload are detected by detecting an output from plural load sensing elements 45 supporting the clamped body.

Abstract: In a machine tool having a worktable feed mechanism of the type that a worktable is moved in a horizontal direction relative to a tool spindle along a pair of guideways in parallel with the horizontal direction, there is provided a cutting chips collection space formed between the pair of guideways fixed to a base. A pair of ball screws are arranged outside of the cutting chips collection space for moving the worktable relative to the tool spindle in the horizontal direction. The cutting chips and coolant generated by contacting a tool with a workpiece drop into the cutting chips collection space directly without being heaped onto a cover mechanism of the worktable feed mechanism.

Abstract: A rotary table with an index apparatus. The index apparatus includes first and second circular coupling gears disposed on a table in coaxial relationship with the rotational axis of the rotary table. The first coupling gear is fixed to the rotary table via a circular support member made of an elastic material while the second coupling gear is fixed to the table base. A third circular coupling gear is further disposed between the first and second coupling gears and the rotary table. The third coupling gear is moved by a cylinder mechanism between a first position in which the third coupling gear is separated from the first and second coupling gears and a second position in which the third coupling gear is brought into engagement with the first and second coupling gears while the force produced by the cylinder mechanism is transmitted to the rotary table via the third gear, first gear and support member so that the periphery of the rotary table is pushed against the guide surface of the table base.

Abstract: A tool change mechanism in a machine tool includes a tool change arm arranged to attach a protection cover member to the forward end of a spindle head for protection of a ring secured to the forward end of a tool spindle in the spindle head and to remove the protection cover member for replacement with a tool holder of large diameter. The tool change arm is further arranged to insert the tool holder into the tool spindle and remove it from the tool spindle, the tool holder having a ring gear secured thereto for meshing engagement with the ring gear of the tool spindle and a protection cover part integrally formed therewith to be coupled with the forward end of the spindle head for protection of the ring gears meshed with each other when the tool holder has been inserted into the tool spindle. The tool change arm has a pair of tool grippers each having a first grip portion for engagement with the protection cover member and a second grip portion for engagement with the tool holder.

Abstract: A pallet exchange apparatus for a machine which includes a base, a pallet exchange arm rotatably mounted on the base, a turntable rotatably mounted on the base, an engaging mechanism provided on the turntable and a pallet guide mounted on the turntable. The pallet guide is shifted between a first position where a pallet supported thereon engages with an engaging portion of the pallet exchange arm and disengages from the engaging mechanism and a second position where the pallet engages with the engaging mechanism and disengages from the engaging portion of the exchange arm. The pallet exchange arm is rotated so as to exchange the pallets engaged with the engaging portion thereof between the turntable and a table of the machine.

Abstract: A pallet changer including an arcuate clamp rail adapted to engage and support a pallet slidably, the arcuate clamp rail being provided in a work table in a machining center, and a plurality of arcuate support rails adapted to engage and support pallets slidably, the arcuate support rails being provided on a pallet pool so that they can be indexed to a pallet changing position. The support rail indexed to the pallet changing position completes a circular track for pallet conveyance conjointly with the clamp rail. Further, a swivel arm is disposed for rotation between the work table and the pallet changing position, the swivel arm being provided at both ends thereof with engaging hooks each capable of engaging an engaging block of each pallet disengageably. By the rotation of the swivel arm, two pallets are exchanged simultaneously along the above circular track between the work table and the pallet changing position.

Abstract: A machine tool having an automatic tool changer for transferring tools between a tool magazine and a horizontal tool spindle rotatably mounted in a spindle head and which includes a vertical head which rotatably carries a vertical tool spindle and a horizontal drive shaft connected thereto is removably mounted on a vertical head support. In advance of a machining operation on a top surface of a workpiece, relative movement between the vertical head support and the spindle head is effected in a vertical direction and first and second horizontal directions, so that the vertical head is mounted on the spindle head, with the drive shaft being drivingly connected with the horizontal tool spindle. A tool support station mounted on the vertical head support is provided with two tool grippers each for vertically holding a tool.

Abstract: In a machine tool with an automatic tool change function, a rotatable tool spindle carries a key engageable with a key-way formed on a tool. A tool change arm, serving as a tool support device, rotatably supports at least one tool to selectively insert and remove the same into and from said tool spindle. When a tool change operation is to be performed, the rotation of the spindle is changed into a predetermined speed suitable for the key-way engagement. An operating device is provided for causing relative movement between the tool change arm and the spindle to insert a tool into the spindle. However, the relative movement thereof is stopped by a stopping device just before the engagement of the key with the key-way. Subsequently, when a first detecting device detects that the key has reached a predetermined angular position, the relative movement of the tool change arm is permitted to thereby make engagement of the key with the key-way.

Abstract: A contact detecting apparatus for detecting the contact between a workpiece and a tool in a machine tool which includes a coil mounted on a spindle head and connected to an AC power source for generating an induced current in a looped secondary circuit including the workpiece, a work table, a machine body, a spindle head, a brush, a clamp bar for clamping the tool on a tool spindle, springs interposed between the spindle and the clamp bar, the tool spindle and the tool, when the workpiece and the tool are moved relatively into contact with each other. The brush is kept contact with the clamp bar at the rotational axis of the tool spindle. A detector is connected between the AC power source and the coil for detecting a change in an electric signal caused by the contact between the workpiece and the tool.

Abstract: A tool exchanger wherein an exchange arm fixed on one end of a rotatable and axially slidable shaft is formed with a pair of semi-circular openings at opposite ends thereof. A pair of gripping plungers slidably received in the exchange arm are spring-biased toward opposite ends of the arm for gripping tools held in the semi-circular openings. A pair of guided pins are protruded respectively from the gripping plungers. A cam engageable with the guided pins is disposed in position to inwardly retract either of the gripping plungers which approaches a tool socket of a tool magazine, against the force of an associated bias spring, when the exchange arm is pivoted from a parked position toward a grip position for gripping tools received respectively in a machine tool spindle and the tool socket.

Abstract: A control system having a touch sensing circuit for emitting a contact detection signal when contact is made between a workpiece and a touch sensitive tool received in a tool spindle of a machine tool. An auxiliary controller is also provided for controlling movement of the tool spindle relative to the workpiece along orthogonal axes by applying feed pulses and axis designation signals to a numerical controller after switching the operational mode of the numerical controller. The auxiliary controller responds to the contact detection signal to align the tool spindle with the center of a workpiece bore when receiving a centering instruction and to measure the diameter of the workpiece bore when receiving a measuring instruction. The system is further provided with a motor control circuit which controls a motor to rotate the tool spindle during the centering operation. The motor control circuit inhibits the rotation of the tool spindle during the measuring operation.

Abstract: An automatic centering controller for centering the axis of a tool spindle of a numerically controlled machine tool on the axis of a reference circumferential surface of an article mounted on the machine tool. The controller comprises a touch sensing device mounted in the tool spindle for detecting the touch of a probe thereof with the reference circumferential surface, a pulse generator for applying feed pulses to servomotors through a numerical controller so as to move the tool spindle along X and Y-axes, and a pulse control device connected to the touch sensing device, the numerical controller and the pulse generator.

Abstract: In a pallet exchange apparatus for a machine tool, a rotary member carried to be rotatable in a horizontal plane mounts thereon a pallet support means which in turn supports a pallet unloaded from the machine tool and a pallet to be loaded into the machine tool. Each pallet is provided with an engaging hook. A transfer member is provided with a transfer hook engageable with the engaging hook to move the pallet to be loaded on the machine tool toward the machine tool. A fixed hook is provided to be engageable with the engaging hook. The rotary member is rotated to move the engaging hook of the pallet to be loaded on the machine tool into engagement with the transfer hook and to move the engaging hook of the pallet unloaded from the machine tool into engagement with the fixed hook.