Patent GB-837098-A (GB)
Title: Fully automatic electrical control for a crankshaft milling machine
IPC: G05B19/06
Filed: 1956-03-27
Abstract: 837,098. Milling crankpins. MAECKER, K., [trading as ELEKTROANTRIEB K. MAECKER]. March 27, 1956 [March 28, 1955], No. 9547/56. Class 83 (3). In a crank-shaft milling machine having electrically-operated means for rotating a crankshaft supported in position to be milled, an electrically-operated milling tool carried by a tool support, electrically-operated displacement means for displacing the tool support lengthwise of the crank-shaft to be milled, and electricallyoperated feed-means for effecting transverse relative movement of the tool support and the crank-shaft to be milled, an electrical control system comprises a number of bars mounted on the machine frame in parallel spaced dispositions, and each has a series of abutments spaced along its length. The system also includes firstly, a number of limit-switches mounted on the tool support of the milling-machine in positions such that each of them is movable, with the tool support, along the length of a corresponding one of the abutment bars so as to be actuated by the abutments on the latter and, in response to such actuation, to arrest longitudinal displacement of the tool support at successive milling-positions, each corresponding to one of the crank-pins in the crank-shaft to be milled; secondly for each milling position in the machine, switching means including a selector device which determines, for that milling position, the angular position into which the crankshaft is indexed; thirdly, for each milling position in the machine, switching means including a selector switch which determines the number of feed movements at that position so as to effect one or more milling operations with, in the case of two or more milling operations, intermediate longitudinal displacement of the tool support, and finally a step-switch mechanism which is operatively connected with said switching means so as to control the sequential operation thereof, and which is adjustable by a selector switch so as to control displacement of the tool support, in response to actuation of said limit-switches, between successive milling positions between any milling position and the final end position. In the Figure, SSW represents the step-switch enabling up to eight pins to be machined, the desired number being set by the rotatable selector-switch P3, shown set for four pins. Switches N1-N8 are the switching means which determine whether one or two cuts are to be taken, the closing of switch N4 indicating that two cuts are to be taken on the fourth pin. Two or more cuts are necessary when the width of the pin exceeds that of the cutter. The cutter has a radius greater than the throw of the crank-pins and is reciprocated, in time with rotation of the crank-shaft about its axis, by the electric motor which rotates the shaft. This motor, running at a lower speed, also serves to index the crank-shaft when it has been declutched from the cutter-reciprocating means. When the milling-slide is in a withdrawn position and at the end of a traverse, a switch is operated to start the traverse motor at the higher of its two speeds. There are two abutment-bars which are alternately rendered effective, either automatically or by pushbutton control, the two bars enabling consecutive-abutments to be positioned more closely to one another than is possible with a single bar. Each abutment has two steps which are effective to operate the high and low speeds of the traverse-motor respectively. When the slide approaches a working position, an abutment first actuates a switch to slow the motor, and then its second step stops the motor and releases a magnetic clutch to disconnect the slide from the motor. Coaxial with the workpiece is a drum carrying a number of dogs set according to the angular position of each pin to be machined. The stepping-switch is not operated until the work has been indexed to the correct angular position for the next pin.