Abstract: The cutting force applied between the cutting tool and the workpiece of a machine tool is periodically pulsated to expedite removal of material from the workpiece. The periodic cutting force pulsation is produced by periodically varying the spindle speed or the feed rate or both. In one embodiment, the periodic speed variation is produced by universal joints in the spindle drive and worktable drive. In a second embodiment, the periodic speed variation is produced by elliptical gears in the spindle drive and worktable drive.

Abstract: A fuse mounting arranged to isolate live electric parts and provided with grounded exposed parts comprises a housing structure, a hingedly mounted fuse panel disposed within said housing structure and normally forming a part of a fuse isolating wall within said housing structure, fuse mounting means secured to the interior of said fuse panel so as to isolate a fuse mounted on said fuse mounting means, conducting means in the form of an electric bushing and its associated bushing well mounted on and projecting through said fuse panel and forming a connection between one terminal of the fuse, disjointable connecting means in the form of an elbow connector engageable with said bushing on the exterior of said fuse panel and outside said isolating wall to form a disjointable electric connection with said bushing, and latch means movably mounted on said fuse panel and engageable with a locking slot formed in said isolating wall for removably securing said fuse panel in its normal position in said isolating wall.

Abstract: A surge arrester of compact construction includes a housing formed preferably of elastomeric material through which a pair of spaced terminals protrude and between which a stack of metal oxide varistor discs is disposed and connected in series therewith. Disposed below the lower one of the discs and in contact therewith is a conductive base plate and an electrode is spaced somewhat from the lower surface of the base plate to form a gap and is provided with shunt means connecting the electrode with the upper surface of the lower disc so that an overvoltage surge condition and the resulting arc across the gap establishes a shunt circuit around the lower disc.

Abstract: A toolholder adapter has a cylindrical body, a cylindrical shank extending axially from one end of the body, a cylindrical flange extending radially from the body, a tapered socket within the body for receiving a tapered shank toolholder, and a clamping nut on the body which has inwardly projecting tabs that are positioned to bear against the flange of the tapered shank toolholder to clamp it in the socket. The toolholder adapter is dimensioned to fit in the tool storage magazine of a machine tool and to be handled by the automatic tool changer thereof.

Abstract: A tool storage drum which is adapted to receive and store a plurality of toolholders is rotatably mounted on top of the upright of a horizontal machining center behind the spindle thereof. A tool changer carriage carrying a tool change arm is pivotally mounted on the upright above the spindle and is pivotable between a parked position in which an end of the tool changer arm is adjacent to the tool storage drum and an exchange position in which an end of the tool changer arm is adjacent to the spindle. The tool changer arm is slidably mounted on the carriage for movement between an extended and a retracted position to remove toolholders from their sockets or insert them therein and is rotatable through 180.degree. to interchange its ends for the purpose of exchanging a tool in the spindle for a tool previously removed from the tool storage drum.

Abstract: Two pairs of crossed tool change arms are mounted adjacent to four spindles which are rotatably mounted on a common spindlehead. Each pair of crossed tool change arms is mounted on a common shaft which is rotatable and is movable along its axis and is positioned to simultaneously insert a pair of tools into or remove a pair of tools from the corresponding pair of spindles. A tool storage chain carrying a plurality of tool storage sockets is movably mounted on a frame in position to interact with the tool change arms which are operable to transfer tools from the tool storage sockets to the spindles and vice versa. Each tool storage socket is pivotally mounted for movement between a vertical storage position and a horizontal tool change position. Four tool storage sockets are pivoted from the vertical storage position to the horizontal tool change position for each tool change operation.

Abstract: A rotary table is driven by a pair of perpendicularly disposed linear slides which are each driven by a ballscrew drive. One of the linear slides is mounted on the movable member of the other linear slide and is coupled to the rotary table by a crank stud. The linear slides are driven at speeds which vary in accordance with the sine and cosine of the table angle to translate the linear slide motion into rotary motion.

Abstract: The feed rate of a computer controlled machine tool is periodically calculated every 9.6 milliseconds to produce a horsepower equal to a target horsepower at the cutting tool during a milling operation. When the feed rate rises above a predetermined level, the target horsepower is progressively lowered, and when the feed rate drops below a predetermined level, the target horsepower is progressively raised. The total amount of cutting time for each tool is measured and the amount of cutting time under increased target horsepower is also measured. When the amount of cutting time under increased target horsepower exceeds a predetermined percentage of the total cutting time for any given tool, a DULL TOOl signal is generated and the designated tool is subsequently replaced. If no cutting time is recorded, a BROKEN TOOL signal is generated and the broken tool is replaced.

Abstract: A Drawbolt is rotatably mounted within the spindle of a machine tool to secure a toolholder to a socket in the front end of the spindle. First and second spur gears are formed on the rear end of the spindle and drawbolt, respectively, and are positioned side by side. The two spur gears are equal in diameter, but have differing numbers of teeth. A planetary gear cage surrounds the spur gears and has pinion gears which are meshed with both spur gears. The planetary gear cage is attached to the armature of an electric motor which, when energized, rotates the cage and thus causes rotation of the drawbolt at a reduced speed. The speed reduction depends on the difference in the number of teeth in the two spur gears. The armature is axially shiftable to move a locking ring on the planetary gear cage into and out of engagement with the spur gear on the spindle.

Abstract: A method and apparatus for transferring digital data between a mass memory and a random access memory. The mass memory has a plurality of memory loops, each having a plurality of memory cells, and a read/write device which either outputs data from the memory cells or inputs data to the memory cells. Each memory cell is identified by an address that specifies its place in the loop sequence starting from a reference cell. A loop position counter is set at zero when the reference cell of the selected memory loop is at the read/write device. The loop position counter is advanced by one count each time the next memory cell in the sequence is moved into operative relationship with the read/write device. Transfer of data between the mass memory and the random access memory is accomplished without any delay under the control of a random access memory address counter which is synchronized with the loop position counter.

Abstract: The spindle head of a gantry type vertical spindle machining center is slidably mounted on a spindle base which is pivotally mounted on the saddle for rocking movement about a horizontal axis to cause the axis of the spindle to tilt from the vertical. A tool storage magazine is mounted on the spindle base and is tiltable along with the spindle to enable toolholders to be transferred between the spindle and tool storage magazine at any spindle tilt angle. A tool changer arm is mounted on the tool storage magazine for transferring tools between the spindle and the tool storage magazine.

Abstract: A numerically controlled machining center has a tool magazine, automatic tool changer, workpiece shuttle, and a workpiece magazine which holds enough workpieces for operation by the machining center for an entire shift of approximately eight hours. The numerical controls are programmed to perform predetermined machining operations on each workpiece, in turn, and to replace each finished workpiece with a fresh workpiece at the end of each machining program. A proximity switch is mounted on the machining center for checking tools to detect broken or incorrect tools. The tools are positioned adjacent to the proximity switch and are rotated while the output of the proximity switch is counted for one complete rotation of the tool to determine the number of radially extending teeth on the tool. If the tool has too few or too many teeth, thus indicating a broken or incorrect tool, it is replaced by another tool of the same type.

Abstract: The bed and upright of a machine tool are made of structural steel tubes which are welded together to form unitary structures. Each of the structural steel tubes is substantially rectangular in cross-sectional shape.

Abstract: The worktable and pallet shuttle of a machine tool are driven by a common motor which is mounted on the worktable base. The motor is coupled to the worktable by gears which engage when the worktable is raised to be indexed and disengage when the worktable is lowered. The motor is coupled to the pallet shuttle by gears which engage when the worktable base is moved into the shuttle position and disengage when the worktable base is moved out of the shuttle position.

Abstract: A tool storage drum which is adapted to receive and store a plurality of toolholders is rotatably mounted on top of the upright of a horizontal machining center behind the spindle thereof. A tool changer carriage carrying a tool change arm is pivotally mounted on the upright above the spindle and is pivotable between a parked positon in which an end of the tool changer arm is adjacent to the tool storage drum and an exchange position in which an end of the tool changer arm is adjacent to the spindle. The tool changer arm is slidably mounted on the carriage for movement between an extended and a retracted position to remove toolholders from their sockets or insert them therein and is rotatable through 180.degree. to interchange its ends for the purpose of exchanging a tool in the spindle for a tool previously removed from the tool storage drum.

Abstract: A tool changer drum is rotatably mounted on a machine tool for rotation about an axis which is perpendicular to the spindle axis thereof. A plurality of tool changer arms are swingably mounted on the tool changer drum for swinging movement along radii of the drum between a storage position parallel to the central plane of the drum and a transfer position perpendicular to the central plane of the drum. A pneumatic cylinder is used to index the tool changer drum to place any selected tool changer arm in the ready position. Another pneumatic cylinder is used to swing the ready tool changer arm from its storage position to its transfer position to transfer a toolholder from storage to the spindle and later to swing the tool changer arm back to the storage position to return the toolholder to storage. Before the tool transfer operation, the spindle is moved to a tool transfer position in which the swinging movement of the tool changer arm either places a toolholder in the spindle or removes a toolholder therefrom.

Abstract: The tape in a tape reader is braked to a stop relatively slowly instead of being stopped on one character. Two sprocket reading photocells are mounted on the tape reader to provide quadrature sprocket waveforms which are applied to a bi-directional sprocket counter coupled to the address conductors of a buffer memory. The data read off the tape by the tape reader is written into the buffer memory at the addresses indicated by the sprocket counter. An output pointer counter is also coupled to the buffer memory address conductors in parallel with the sprocket counter through a time division multiplexer. During the time interval in which the output pointer counter is connected to the buffer memory address conductors, data can be read out of the buffer memory at the address indicated by the output pointer counter independently of the sprocket counter.

Abstract: An electronic data processing system which utilizes a variable timing period that is varied in accordance with the access time of the digital devices or circuits utilized in each step of the data processing program. In one embodiment, the data processing system is a computer which performs the basic arithmetic and logical operations. The computer utilizes three memories which have different access times. One memory stores instruction words specifying steps in a computer program for performing basic arithmetic and logical operations involving predetermined data words; another memory stores the data words; and, the third memory stores control words specifying the various machine operations required to execute the corresponding instruction. The three memories can be read out simultaneously, two at a time, or one at a time. In each case, the timing strobe which initiates the next step in the program is generated immediately after the slowest memory utilized in that step is ready for the next readout.

Abstract: A plurality of machine tools are linked together by a material handling system which carries workpieces from one machine tool to the next in line along a conveyor. The workpieces are clamped to pallets which are carried on conveyor carts between machine tools and which are shuttled onto the machine tools under the guidance of a material handling computer which controls all of the conveyor carts and pallets in the system. The limit switches which indicate the position of the carts and pallets are wired to the material handling computer over a novel data communication link which uses only two pairs of conductors for each machine tool and each section of the material handling system.