One-direction Rotating Blade For Sewing Machines Cutters

Abstract

A cutting mechanism for use on sewing machines having a single unidirectionally, movable cutter blade that cooperates with a fixed or stationary blade, the movable blade being rotatable upon command and being automatically and positively braked after rotation past the cutting position.

Description

BACKGROUND OF THE INVENTION

It can readily be appreciated that in the use of sewing machines, and particularly in the area of those machines used for the industrial production of clothing and related articles, that the working speed of the machine is one of the most important factors. This is true because the speed with which the machine will operate affects the economics of the production of the final sewn articles. A principal limitation to increases in sewing or seaming speed has been due to the use of scissors-type cutters in which one movable scissor blade oscillates back and forth in cooperation with a fixed or stationary blade. More particularly, in sewing machines utilizing the oscillating scissor construction, the movable or oscillating blade for a finite length of time blocks the fabric that is being sewn and prevents its movement further down the working table. This occurs not only during the cutting operation but also during the time that is required for the movable blade to move back to its original rest position.

It is therefore a principal object of this invention to provide an improved cutter for use with sewing machines that does not block the continuous movement of sewn articles from the working station.

Another object of this invention is to provide an improved cutter that utilizes a movable blade that travels only in one direction when performing its cutting function and when returning to a rest position.

Other objects and advantages of this invention will be in part obvious and in part explained by reference to the accompanying specification and drawings.

BRIEF DESCRIPTION OF THE DARWINGS

FIG. 1 illustrates in schematic plan the present cutter mounted on a sewing machine and also the electrical control circuit for the cutter;

FIG. 2 shows a transverse sectional view of the clutching-drive means and the braking apparatus;

FIG. 3 shows a top plan view partially in section showing the way in which the movable blade is mounted;

FIG. 4 is a side elevation of the apparatus shown in FIG. 3 indicating the path of travel of the movable cutter blade; and

FIG. 5 is a top elevation showing the cooperating cutting blades in cooperating position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 of the drawings there is shown a sewing machine 1 made up of a standard or arm 2, a supporting base 3, an arm 4 and a work supporting surface 5. At the end of arm 4 there are located a needle bar 6 and a presser foot 7 that cooperates with the needle bar 6 to perform the seaming operation. It can also be seen in FIG. 1 that the sewing machine 1 has on it an auxiliary puller 8 that assists in drawing the fabric through the sewing station.

The cutter of the present invention is of the type where a fixed blade 9 cooperates with a movable blade 10. As was previously mentioned, this type of cutting operation is essentially that of a pair of scissors, but unlike the conventional scissors where one blade is oscillated back and forth to cooperate with the stationary blade, the present movable blade 10 travels in a complete circle so that when it has moved past the cutting station it is completely removed from the plane of the fabric. The fixed blade 9 is mounted on the machine by a conventional means which here are shown as rivets 11 in FIG. 5 of the drawings. In this case the rivets are secured to a small bar 12 that is secured by means of screws 13 to support 14 which support is in turn secured to the base 5 of sewing machine 1.

A shaft 15, FIG. 3, is mounted in support 14 for rotation to carry the movable cutting blade 10. Also on shaft 15 there is a cog wheel 16 which is keyed to the shaft and is responsible by means of toothed belt 17 for the rotation of the shaft 15. On the other end from the cog member 16 the shaft is provided with a radial projection 18 that retains a biasing spring 19 within the recess 20 formed in the support 14. The purpose of this biasing spring is only to assure that close contact is maintained between the cooperating pairs of cutter blades 9 and 10. The cog wheel is driven and it in turn affects rotation of the shaft 15 by means of the toothed belt 17 that extends from member 16 to a clutching arrangement (to be described) and ultimately to the suitable drive means which is shown in FIG. 1 as an electric motor 36.

More specifically, the cog wheel 16 is by means of belt 17 connected with a cog wheel 21 that is securely attached to an elongated drive shaft 22. Shaft 22 is common to an electromagnetic clutching arrangement and also to braking means which are located on the opposite end of the shaft 22. The entire clutching and braking mechanisms are shown generally by the numerals 23 and 24. Shaft 22 is rotatably mounted within the bearings 26 on frame 25. Turning first to the electromagnetic clutch 23, this clutch includes a first conductive part 27 which is attached to shaft 22 by means of the set screw 28. The conductive part 27 also includes a frictional face disc 30 which is suitable to make good frictional engagement with a second conductive part 29. It can be seen that part 29 can slide in a direction parallel with the longitudinal axis of the shaft 22. Part 29 is mounted directly on the hub of pulley 31 which is in turn mounted for rotation on shaft 22 by means of bearings 32. The pulley indicated by numeral 31 is connected by means of the belt 33 to pulley 34 that is keyed on the shaft 35 of the drive means comprised of electric motor 36. The electromagnetic clutch 23 includes an excitation coil 37 which is contained in frame 25.

The brake 24 is also electromagnetically operated and includes a braking part 38 which is stationarily affixed to the frame 25. Part 38 of the brake 24 includes a friction material 40 that is suitable to engage the element 39. Element 39 is mounted in such a way that it must rotate with rotation of shaft 22 but can at the same time move in a direction parallel to the longitudional axis of shaft 22. Sliding occurs on a wheel 41 which is affixed to the shaft by means of the set screw 42. The numeral 43 indicates the excitation winding of the brake 24 and this winding is carried on the frame 25 in the same fashion as coil 37 of the electromagnetic clutch.

Referring again to FIG. 1 of the drawings, it can be seen that the circuit used to energize the excitation coils 37 and 43 include as important components a rectifier bridge 46, a condenser C, a manual actuating switch 47, a diode 48 and a cam operated switch 49. Also involved are switches R1, R2 and a relay R. It is the function of the switch 47 to either connect the bridge rectifier 46 to the condenser C for the purpose of charging the condenser or to close the other of the two circuits that it is connected with. There it allows the condenser C to discharge through the diode 48 and then into one of the coils 37 or 43, depending upon which way switch R2 has been closed. Assuming that the switch 47 is moved from the position shown in FIG. 1 to the other of the two positions, then condenser C will discharge and send excitation current to the winding of relay R which will then close the first contact R1 and then the contact R2 to energize winding 37 of the electromagnetic clutch. Under these conditions, coil 37 is fed with current and the part 27 attracts the element 29 which is driven by the motor 36. This causes rotation of shaft 22 and then by means of tooth belt 17 the cog wheel 16 is rotated and the movable blade 10 begins its rotation about shaft 15. At the time this action has occurred, the movable blade will move from the position indicated by the dotted line in FIG. 4 and designated by numeral 10a to the position shown and indicated by the numeral 10b. When blade 10 has reached the position 10b, it will be apparent that at this point it has ceased its cutting function since it has traversed the entire width of the permanently mounted cutting blade 9. At this point in time, the cam 44 acts upon switch 49 so that the relay R will be de-energized and cause contact R1 to open while at the same time contact R2 is closed to permit the energization of coil 43 of the brake 24. When cam 44 has brought about this change in conditions the part 38 (FIG. 2) attracts element 39 and thereby interlocks the parts to shaft 22. Thus, by means of tooth belt 17 a positive connection is made to the movable blade 10. When this occurs, the movable blade 10 is as indicated in FIG. 4 moved from the position indicated by numeral 10b to the position indicated by numeral 10a, the rotation in all cases being clockwise as viewed in FIG. 4. Obviously even if switch 47 is kept in the position which could cause discharge of condenser C, no such discharge can occur because the condenser must be recharged by first returning it to the original position shown in FIG. 1. Thus the blade 10 is essentially locked in the position shown by the numeral 10a and cannot move on to perform another cutting position.

Although the present invention has been described in connection with preferred embodiment, it is to be understood that modifications and variations can be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and the appended claims.

Claims

What we desire to claim as new is:

1. A workpiece cutter for sewing machines comprising:

a. a stationary cutter blade mounted in fixed position on said sewing machine;

b. a movable cutter blade mounted operatively adjacent said stationary cutter blade for unidirectional turning in a cutting direction about an axis of rotation whereby said workpiece is cut between said movable and stationary blades;

c. an elongated drive shaft having means connected thereto for rotating said movable cutter blade;

d. a first conductive clutch plate fixedly secured to said elongated drive shaft;

e. a drive pulley mounted for free rotation about said drive shaft;

f. a second conductive clutch plate mounted on said drive pulley for rotation therewith, said second plate being movable axially parallel to the axis of said elongated drive shaft to engage said first clutch plate;

g. drive means operatively connected to said drive pulley to effect constant rotation thereof;

h. braking means operatively connected to said elongated drive shaft; and

i. means causing said first and second clutch plates to engage each other when rotation of said movable cutter blade is desired and to disengage each other when said brake means is operated.

2. A workpiece cutter as defined in claim 1 wherein said means to engage and disengage said first and second clutch plates includes cam means effective to stop rotation of said movable cutting blade after it has moved unidirectionally past said stationary blade.

3. A workpiece cutter as defined in claim 2 wherein said cam means is mounted on the same shaft as said first conductive clutch plate and said braking means.

4. A workpiece cutter as defined in claim 1 wherein said first and second clutch plates and said braking means are electromagnetically actuated.