Abstract: A drill press having a safety device for reducing the power to the motor when a drill bit becomes stuck, and a switch for temporarily overriding the safety device, when the latter is triggered by the drill bit becoming stuck, to temporarily increase the power to the motor for freeing the stuck drill bit. The switch has an actuating member, preferably a push-button, located at the end of the control lever whereby the operator can actuate the switch without letting go of the control lever. The front of the drill press preferably has a control panel with input and operating keys.

Abstract: In an electropneumatic drill or chipping hammer with an air cushion transmitting driving force of an exciter piston to a percussion piston, a clutch is provided to interengage a drive motor with the exciter piston. The clutch can be selectively engaged by an axially displacing holding sleeve which positions a tool on the front end of the drill or hammer.

Abstract: A power tool in which feed rate information is used as a means of changing cutting implement speed to maintain an optimum chip rate removal. As the tool is loaded by a feed rate increase, the motor speed will increase to that point empirically determine to provide a good finish for the material and cutting implement size selected. If the load decreases, the motor speed will correspondingly decrease to that speed which will provide a good finish for the material and cutting implement size selected with out overheating of the material. A limit would be set to indicate to an operator when he is at the upper limit of the speed and feed rate range and turn off the tool after a short period of time to prevent destructive overheating.

Abstract: A tool holder assembly which includes a support and a chuck for a tool is disclosed in which the tool holder may be responsive to either torque or thrust overload, or a combination of both. The tool holder includes a movable signal member in the form of a longitudinally movable sleeve which may be actuated rearwardly to actuate a proximity switch to stop rotation of the tool holder assembly, for example. Spring means acts between the chuck and the support, with this spring means being preloaded. A hemispherical projection and a conical recess act between the chuck and the support so that if a longitudinal thrust is provided on the tool and chuck, it is transmitted directly through this projection and conical recess to additionally prestress the spring means and to rearwardly move the signal member sleeve.

Abstract: A power tool has an electric motor with a motor shaft having a spiral gear through which the motor drives the tool. A pressure sensor is disposed so as to be subjected to the axial thrust of the motor shaft created by the spiral gear during operation of the tool. A torque control device is connected to the pressure sensor for influencing the motor in response to such axial thrust, for example to control or limit the torque of the motor. Preferably, the pressure sensor comprises a disk of electrically conductive plastic and is located between a thrust bearing of the motor shaft and an axial support therefor. Such disk is disposed between a pressure plate and an electrode plate having spaced apart electrodes.

Abstract: When a drill is overloaded, while cutting a hole in a workpiece, a torque limiter disconnects the drill from a main spindle. As the drill is disconnected from the main spindle, the torque limiter generates high-level elastic waves. The elastic waves are converted by a transducer into a voltage signal. The level of the voltage signal is compared with a threshold value.

Abstract: A servo system for the rotary spindle of a machine tool in which the spindle is driven by a drive motor through a gear train having shiftable gears for changing the rate of rotation of the spindle. The transducer for the servo system is mounted directly on the motor drive shaft in order to avoid all backlash between the resolver and the drive motor. However, the transducer is arranged to regulate the angular orientation of the spindle and must therefore be maintained in synchronism with the spindle. This is accomplished by arranging the shiftable gears so that when they are moving into engagement with a new gear, engagement with the previously engaged gear is maintained until initial engagement with the new gear is achieved. Further shifting movement into full engagement with the new gear operates to release the previously engaged gear. Thus, during the initial engagement with the new gear, the shiftable gear is momentarily in engagement with both gears.

Abstract: An electronic power tool provided with a microprocessor operated speed control system and having a multiple gear reduction drive mechanism is provided with a gear ratio indicator system employing a dual purpose cam shaft for coordinating the mechanical gear shifting and electrical microprocessor systems. The cam shaft is provided with a first cam element for performing the gear shifting function and a second cam element, operably interconnected with the first cam element for automatically moving a switch between positions corresponding to the gear engagement selected. The switch is electrically interconnected with the microprocessor to communicate the gear ratio selected thereto.

Abstract: A drill employed for drilling holes in airframes is provided with means to rotate the drill bit during retraction and means to control the rate of retraction of the drill bit from the hole in a manner to prevent the formation of axial scratches in the wall of the hole.

Abstract: A mechanism for reversing the direction of rotation in a drilling apparatus comprising a feeding beam (1) and a drilling machine (3) supported by the beam for longitudinal movement back and forth along the beam in a drilling direction (A) and an opposite return direction (B) by a feeding mechanism (4). The drilling machine is provided with a pressure medium driven rotating device (9) for rotating a drilling rod and with a reversing valve (13) connected to the pressure medium system of the rotating device. The reversing valve is provided with a spindle rotatable between two positions in which the rotating device rotates the drilling rod in opposite directions. The reversing mechanism comprises two actuating elements (24,27) rotatable with respect to each other. One element (24) is in rotational engagement with the spindle and is moved axially together with the spindle at least at the end of the return direction of the drilling machine.

Abstract: A tapping machine provided with a quill for rotatably supporting a spindle which holds a tap on one end thereof, a reversible electric motor for rotating the spindle and axially reciprocating the quill, an overload release clutch mounted in a power transmitting mechanism which is disposed between the quill and the motor, for suspending the power transmission between the quill and the motor when an overload is applied on the quill, and pulse signal generating means mounted between the clutch and the quill in the power transmitting mechanism for generating one pulse signal in response to each one pre-set unit distance of the quill during the forward motion thereof. The tapping machine performs a working cycle in good order wherein the spindle advances from the start position while being forwardly rotated until the number of pulse signals generated from the pulse signal generating means accords with a pre-set number and returns while being backwardly rotated back to the start position.

Abstract: A speed control device for portable power tools having particular applicability to electric drills. The speed control device is adapted to automatically adjust the speed of the motor in accordance with changes in the diameter of the tool bit used. The device includes a sensor that senses the opening and closing of the jaws of the chuck. The sensor is mechanically coupled to a potentiometer circuit whose output signal is varied in accordance with movement of the sensor. The output signal of the potentiometer circuit controls the firing angle of a thyristor 34, which in turn controls the current supplied to the motor. In addition, the preferred embodiment includes a speed select switch which is connected to the potentiometer circuit to set the appropriate speed range for the motor, given the particular type of work material.

Abstract: An improved drafting instrument is provided for scribing small dots on a drafting medium comprising a substrate provided with a removable surface coating. The drafting instrument includes a drive motor and rotatable cutter which are slidably mounted as a unit for vertical movement toward and away from the drafting medium. A manually operable actuator is provided for moving the drive motor downward to bring the cutter into engagement with the surface coating of the drafting medium. A control switch responds to downward movement of the drive motor and cutter by a predetermined distance for automatically actuating the drive motor before the cutter is moved into engagement with the drafting medium. The drafting instrument includes an adjustable depth limit feature to control the depth of penetration of the cutter into the surface coating of the drafting medium. The operation of the drive motor and rotation of the cutter are automatically terminated when manual pressure on the actuator is released.

Abstract: This invention relates to a retrofit system for automatically selecting and continuously controlling the rotational speed of a typical machine tool. A plurality of sensors are provided adjacent to the storage receptacles for each of the tools or tool holders. When a tool is removed from the storage location, a pre-set speed reference signal is generated responsive thereto for controlling the rotational speed of the machine tool. A rotational speed sensor may also be included for continuously correcting the rotational speed of the machine tool for speed variations due to loading, voltage variations, etc.

Abstract: Drilling apparatus for driving a drill bit in one pass through several plies of material having different hardness characteristics, and in which the speed of rotation of the drill bit is selected automatically by the thrust resistance encountered by the drill bit. The automatic selection of drill bit speed is accomplished by a feed back system responsive to drill bit thrust for changing the governor control on the drive motor, whereby the increase in thrust effects drill bit speed reduction and a decrease in thrust effects an increase in drill bit speed.

Abstract: A hydraulic drill unit for drilling multimaterial, thick layer stock having a conventional hydraulic drill modified to have its feed controlled by a servo valve and its spindle speed controlled by a servo valve. A linear encoder is attached to the drill to provide an indication of drill position. The linear encoded provides 20,000 forward and reverse pulses per inch, depending upon the direction of travel, which are used to determine net feed rate. The net feed rate signal is compared with a command feed rate to control the feed servo valve. A magnetic pickup is used to provide a pulse signal proportional to RPM. This signal is compared with a command speed signal to control the spindle speed servo valve. Differential pressure transducers are used to measure pressure across the hydraulic feed pistion and the hydraulic drill motor to provide signals which can be used as indications of chip packing or a dull drill.

Abstract: A chuck unit for boring, drilling or cutting tools having a safety clutch so as to prevent overload resulting from broken or dull tools and wherein when the clutch is actuated by an overload a transmitter in the tool support is actuated to radiate a signal which is detected by a receiver so as to indicate the malfunction and/or stop the tool so as to prevent damage to the tool or workpiece.

Abstract: An electric motor driven drill and a battery therefor are mounted within a toolholder for a machine tool. The battery is coupled to the motor through a centrifugal switch which closes when the toolholder is rotated about its axis above a predetermined speed and opens when the rotary speed of the toolholder falls below the predetermined speed. The toolholder is mounted in the spindle of a machine tool and the drill turns on when the spindle is rotated and turns off when the spindle stops, the rotary speed of the spindle being added to the rotary speed of the drill in one direction of spindle rotation and subtracted from the rotary speed of the drill in the opposite direction of spindle rotation.

Abstract: A rotary power drive is provided for delivering a substantially constant horsepower over a wide speed range in one direction of rotation comprising two or more constant displacement hydraulic motive means operatively associated with a shaft to be driven thereby, an overrunning clutch operatively interposed between at least one of such motive means and said shaft, and means for supplying hydraulic drive fluid to such motive means in different combinations over different shaft speed ranges to provide a multiple displacement hydraulic motor drive apparatus.