US2394655A - Servo-motor - Google Patents

Description

Feb. 12, 1946. J BETTER 2,394,655

SERVOMOTOR Filed Dec. 1, 1942 2 Sheets-Sheet 1 Fig? l a /N\/ENTUR/ i 372M Jim F. J. BETTER SERVO-MOTOR Feb. 12, 1946.

Filed Dec. 1, 1942 2 Sheets-Sheet 2 Patented Feb. 12, 1946 SERVO-MOTOR Francis J. Better, Beverly, Mass., assignor to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application December 1, 1942, Serial No. 467,482

1 Claim.

This invention relates to servo-motors by which work-portions may be pressed together in preparation for an operation upon them. An example of a machine to which the invention may,

usefully be applied is furnished by that disclosed in Letters Patent of the United States No. 1,971,344, Hardy, August 28, 1934, though it may find other desirable applications.

In the machine of the above patent, a heel and a lasted shoe are positioned for the attachment of the heel to the heel-seat of the shoe, and are then clamped for the operation upon them when a treadle is depressed .by the operator. This brings a clamping member into contact'with the crown of the last-cone, and then applies a sufficient force to maintain the parts in the relation in which they have been placed. To obtain this initial. engagement promptly, the treadle must be moved through a considerable distance, and, in doing this, the attention of the operator may be distracted from the proper holding of the shoe and heel in position upon the support. When clamping pressure is applied, a substantial force must be exerted by the operator and held for a considerable time.- An object of my invention is to provide for the clamping of the work by simple, compact and effective hydraulic mechanism, which will minimize the necessity for attention and effort on the part of the operator, a slight movement initiating the operation and the clamping force being applied under power. In the attainment of this object, the hydraulic mechanism or servo-motor has a cylinder and a piston operating therein. To the cylinder of the motor, used as previously indicated or in other connections, a pressure-conduit delivers. and the piston in the cylinder has surfaces of different effective areas to which pressure is applied from the conduit. A spring-actuated valve, carried by the piston, controls the application of pressure to these surfaces to vary the force exerted by the motor. A spring-actuated valve-sleeve is shown as surrounding the. piston and governing the introduction to and discharge of fluid from the cylinder through an inlet-andoutlet opening to permit the proper action of the piston. Both of these valves are Within the cylinder and upon the piston- In the accompanying drawings illustrating a particular embodiment of the invention,

Fig. 1 shows a heel-attaching machine with my improved servo-motor in side elevation;

Fig. 2, a front elevation of the controlling treadle and connected valve;

Fig. 3, an enlarged central vertical section through the motor with the elements in their normal positions corresponding to Fig. 1, the upper portion of the cylinder above the dash-dot line being turned through 90 from the actual relation, to better show the inlet-and-outlet-connection;

Fig. 4, an enlarged central vertical section through the motor, with the clamp and a portion of its connections in side elevation, and illustrating the elements upon contact of the clamp with the crown of the last, aportion offthe hydraulic connections being indicated diagrammatically;

Fig. 5, a partial centralvertical section through the motor with the elements as related during the application of clamping pressure; and

Fig. 6, a diagrammatic view of the hydraulic connections, with the operator-actuated valve in exhaust-position.

Upon a frame l0 (Fig. 1) is mounted a support 3 for a shoe S and heel 1-1,. This support is shown as having a plate l2 upon which the tread-surface of the sole of the shoe may rest, a member l4 receiving contact of the treadsurface of the heel and a back-stop l6 for said heel. A clamping member 18, movable into engagement with the crown of a last L within the shoe, is carried by a yoke 20 hung upon a pair of arms 22 pivoted at 24 upon a portion of the support s. The lower ends of the yoke-arms are, joined to spaced arms 26 of an actuating lever l fulcrumed at 28. To

the pivotal connection between the yoke-anus and the actuating lever may be joined treadleconnections, such as those of the previously mensideration here.

The clamp-actuating mechanism of the present invention, organized for ready substitution for the treadle mechanism, is furnished by a servomotor M, having a cylinder 30 attached at its lower end and forward side by screws 32 to the bottom and front wall of a tank 34. This tank has projecting from its wall lugs 36 attached by hooked bolts 38 to a tie-rod 40 of the frame. Extending forwardly from the top of the tank is a horizontal shelf 42 secured to a bar 44 bolted between the sides of the frame. Upon the shelf are a rotary pump 46 for supplying under pressure the motor-fluid, preferably such a liquid as oil, and an electric motor 41 by which the pump is driven. The cylinder 30 of the motor'M has,

crown or the last L within the shoe will be enbores of two diameters, the upper 48 being larger than the lower 50 (Figs. 3, 4 and 5). In the cylinder-portion 48, a piston 52 is movable with the usual sliding fit. Depending from the piston is an extension 54 spaced from the cylinder-wall by a surrounding valve-sleeve 55, sliding within the bore 50 and about the piston-extension. The concave under surface 58 of the piston 52 surrounding the extension 54 has an eflective area greater than the end surface'58 of the extension 54. This compound piston 52, 54 has a rod 60 projecting upwardly from it, this being connected through a slot 82 to an arm 84 of the actuating lever l, the arms 28 of which are Joined to the work-clamping yoke 20. An expansion-spring 86 interposed between the piston 52 and the head 88 of the cylinder 30 hold said piston normally lowered, as appears in Fig. 3 of the drawings. Here, the lower extremity of the extension 54 is just above a port ll, through which a conduit delivers liquid from the pump 46 to the bottom of the cylinder 30. The valve-sleeve 55 is urged normally down upon a shoulder 12 in the cylinder, just above the port II, by an expansion-spring l4, abutting against a shoulder 18 upon the valve-sleeve and upon a ring 18 fixed to the bottom of the cylinderbore 48. This spring lowers the upper edge of the valve-sleeve below an inlet-and-outlet-port 80 near the top of the cylinder-bore 50, this port being connected by a conduit 82 to a body of oil 0 in the tank 34. In the piston-extension 54 are passages joining the upper and lower cylinderportions. These passages are shown as a plurality of grooves 84, formed in the extension from points somewhat above its lower end to merge into the piston-surface 56, the lower extremities of the grooves being connected to an axial bore 86 in the extension by openings 88 through the extension-wall. Flow of liquid through these passages is controlled by a valve-plunger 80 sliding in the bore 86 and held normally down against a stop-screw 82 threaded into the end of the extension, by an expansion-spring 84 surrounding the stem 86 of the plunger and seated against the upper end of the bore.

The conduit 10 is connected through a threewhich pressure is supplied by the pump 46. By actuation of this valve, pressure may be applied to the cylinder 30 or cut off and the conduit 10 connected for exhaust'of the cylinder into the tank through a conduit I 02. During exhaust, the oil, drawn from the tank through a conduit I03 by the continuously operating pump, escapes through an adjustable relief-valve I04 to the conduit I02. To shift the valve I00 between its two positions, there is fastened to its plug an arm I06 Joined by a link I08 to an arm IIO, fast upon one end of a shaft II2 journaled in hangers H4, H4 depending from tie-rods H6, H8 at the bottom of the frame I0. Upon the forward extremity of the shaft is secured a double treadle II8, limited in its oscillation in opposite directions by stop-screws I20, I20 threaded vertically through the adjacent bracket. If the right-hand side of the treadle is depressed by the operator, the valve I00 is set for exhaust from the cylinder (Figs. 2 and 6) Opposite movement of the treadle positions the valve to apply pressure to the cylinder (Fig. 4).

- I With the valve I00 as illustrated in Fig. 2, the

operator applies a heel H to the heel-seat or a shoe 8, and places them together upon the support 3, contact of the rear of the heel with the back-stop I8 determining the point at which the Saged by the clamp. At this time, the clamp is elevated by its connection to the piston 52, 54, which is lowered by the spring 66, exhaust from the cylinder 30 to permit this having occurred through the port II, conduit 10, valve I00, and conduit I02 to the tank 34. The valve-sleeve 55 has been depressed by the spring 14, so the port extension 54. The cylinder-space below the pie-- 80 is open, and theplunger-valve 80 closes the openings 88 to the passages through the piston- 1 ton 52 is filled with oil, drawn in from the tank through the conduit 82 and port 80. This is as ilin Fig. 4. The piston rises rapidly and, through.

lustrated in Fig. 3. The discharge from the pump 46 is wasting back to the tank through the conduit I02. The operator, having determined that the relation of the cup of the heel to the heelseat of the shoe is correct, depresses the left-hand side of the-treadle H8. The valve I00closes, the connection between the exhaust-conduit l02'and the conduit 10 leading to the cylinder, and applies pressure from the pump 46 to the surface 58 of the cylinder-extension 54, as may be seen piston 52 was filled with oil, as already explained,

and this condition is continued during the elevation, the oil entering from the tank 34 through the port 80. As soon as contact of the clamp with the last occurs, the rise of the piston is stopped with the elements related as appears in Fig. 4. The pump-pressure through the port II now becomes effective upon the surface I 22 of the valve-sleeve 55, where it projects beyond the cylinder-shoulder l2, and also upon the surface I24 of the valve-plunger 90. The sleeve is raised to close the port 80, while the plunger frees the openings 88 (Fig. 5). The pressure is thereupon exerted through these openings and the grooves 84 on the larger piston-surface 56, andapplies to the clamp I8 a much increased force to hold the work securely for the operations upon it.

When the chosen maximum clamping pressure has been attained, the oil from the pump blows off through the relief-valve I04 by way of the conduit I02. The attachment of the heel having been completed, the operator restores the treadle 8 to the position of Fig. 2. Pressure is now cut oil the cylinder 30, and this is connected through the conduit 70 and the valve I00 to the exhaustconduit I02. The spring 84 lowers the valveplunger to close the openings 88 and the springs I4 and 66, respectively, restore the valvesleeve 55 and the piston 52, 54 to their initial positions, the valve-sleeve opening the port 80.

The oil, which entered during the elevation of the piston, is displaced through the ports H and 80 nitude with little eflort on his part. There should further be observed, the simplicity of the hydraulic motor, with its valves compactly arranged within the cylinder.

Having described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

In combination, a cylinder having portions of diflerent diameters, there being an inlet-andoutlet opening in the portion of smaller diameter at the end adjacent to the portion of greater diameter, a conduit delivering fluid under pressure to the portion of smaller diameter, a workclamping piston movable in the cylinder-portion of greater diameter and having an extension lying in the portion of smaller diameter, there being passages in the piston-extension connectin: the cylinder-portions, a spring-closed valve movable in the extension and opened by pressure supplied through the conduit to admit such pres sure through the piston-passages to the larger cylinder-portion, and a sleeve surrounding the piston-extension within the smaller cylinderportion and controlling the flow through the inlet-and-outlet opening, said sleeve being springactuated in one direction to open said inlet-andoutlet opening and admit fluid to the cylinder and actuated in the other direction by pressure admitted through the conduit to close the inletand-outlet opening, increase in pressure in the smaller cylinder-portion then opening the spring-closed valve for the application 01 workclampinz pressure from the conduit to the piston.

, FRANCIS J. BE'I'I'ER.

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