US2939414A - Sewing machines - Google Patents

Description

June 7, 1960 Filed Oct. 23, 1957 w. H. SLINN 2,939,414

SEWING MACHINES 3 Sheets-Sheet l INVENTOR fi alfsi' Eerie??? 6222a BYfMMw/ W ATTORNEY June 7, 1960 Filed Oct. 23, 1957 w. H. SLINN 2,939,414

SEWING MACHINES 3 Sheets-Sheet 2 u, INVENTOR ATTORNEY June 7, 1960 w. H. SLINN 2,939,414

sawmc MACHINES Filed Oct. 23. 1957 3 Sheets-Sheet 3 FMW W ATTQRNEY United States Patent 2,939,414 SEWING MACHINES Walter I lerbert Slinn, London, England, assignor to Trubemsed (Great Britain) Limited, London, England This invention relates to sewing machines and similar devices, and more particularly to a sewing machine incorporating means for effecting greater control of the stitching line produced by a sewing machine.

My United States Patent No. 2,684,651 describes apparatus for guiding a workpiece under the needleof a sewing machine along a predetermined stiching line. In this apparatus a work holder, or carriage for supporting a removable frame in which the work is held, is mounted upon guides which allow the carriage to move in a plane in two mutually perpendicular directions. Movements of the carriage in these two directions are respectively effected by a pair of cams mounted on a common shaft,

disposed below the plane of movement of the carriage. The follower of each cam is connected to an intermediate point on a lever, or operating arm, which is pivotally mounted at its lower end has its upper end connected (directly or indirectly) to the carriage.

In the form of apparatus described and illustrated in the above mentioned specification, one operating arm is of telescopic construction and has its upper end pivotally and slidably engaged with a rod which is secured to the carriage and extends parallel to the direction of the movement produced by the other operating arm. Owing to practical difficulties of manufacture, mechanism so constructed does not always work smoothly, but is subject to sticking or jamming.

My United States Patent No. 2,796,034 is concerned with an improved form of operating arm of telescopic construction in which a linkage arrangement is provided for extending the telescopic operating arm. This improved form of operating arm is not subject to the above defect.

Apparatus for guiding a workpiece under the needle of a sewing machine, such as is described in the above mentioned patent specifications, may be used for the manufacture of mens collars and the two mutually perpendicular directions in said plane will be referred to herein as horizontal and vertical. These terms do not refer to the actual directions of movement of the work holder; they are technical terms taken from the standard way of fixing a collar in said work holder, that dimension of the collar which when worn is substantially vertical being called vertical, and that dimension which when worn is substantially horizontal (i.e. the longest dimension) being called horizontal.

Since in a collar the horizontal dimension is much greater than the vertical dimension, special arrangements are preferably made for transferring a straight line motion produced by the respective cam to a straight line motion of the workpiece. For this purpose the telescopic lever arrangement described in our United States Patent No. 2,796,034 may be used. 'Alternatively a link pantograph as described herein may be used, the pick up point of the pantograph being mechanically coupled to the cam follower of the cam for producinghorizontal movement (hereinafter referred to as the ,h'orizontal V 2,939,414 Patented June 7, 1960 cam") of the work holder as described in more detail later. a

Different sets of cams may be provided for different standard sizes of collars to be sewn. It is sometimes desirable to produce sizes between these standard sizes, for example, in order to compensate for shrinkage. The vertical dimension of a collar being smaller and less important as regards fitting may be neglected. To produce these sizes between the standard sizes, according to the present invention, ratio adjusting means are interposed between the pick up point of the pantograph, for example, and the cam follower of said horizontal cam. As will be seen later adjustment of the ratio adjusting means enables the travel of the cam follower to be increased or reduced slightly before being imparted to the pick up point of the pantograph.

One preferred form of the present invention will now be described in detail by way of example only, reference being made to the accompanying drawings. In these drawings:

Figure 1 is a perspective view of an automatic sewing machine provided with a work holder and means for guiding the work holder relative to the needle;

Figure 2 is a perspective view of parts of the machine, showing the work holder and means for guiding and moving it;

Figure 3 is an elevation on a larger scale of the pantograph operating arm and ratio adjusting means;

Figure 4 is a plan view of the mechanism shown in Figure 3, and

Figure 5 is an end view, looking from the left of Figures 3 and 4 showing further details of the ratio adjusting mechanism;

Figure 6 is a section on the line 6-6 of Figure 5, and

Figure 7 is a section on the line 7-7 of Figure 4.

Referring first to Figure l, the apparatus illustrated comprises a sewing machine 5 of conventional construction supported upon a framework 6, which accommodates the means for driving the sewing machine and the apparatus (described below) for moving under the needle of the sewing machine a frame 7 holding the work to be stitched.

As best seen from Figure 2, the frame or work holder 7 is supported in a carriage 8, which is mounted for movement in two mutually perpendicular directions in a horizontal plane. The carriage is supported for sliding movement (in the direction which has been referred to hereinbefore as the horizontal direction) upon a pair of parallel rods 9. The ends of the rods 9 are rigidly secured to a pair of sleeves 10, supported for sliding movement (in the direction which has been referred to hereinbefore as the vertical direction) upon a pair of rods 11, fixed in the framework 6.

Vertical movement of the work supporting carriage 8, together with rods 9 and sleeves 10, is effected by a pair of levers 12, secured upon the ends of a shaft 13, which is jonrnalled in bearings 14, provided in the fixed framework of the machine. The upper end of each lever 12 is pivotally connected about a horizontal axis to a block 15, which engages between a pair of vertical cheeks 10a formed on the corresponding sleeve 10, whereby the upper ends of levers 12 are firmly connected to sleeves 10 for movement in a vertical direction, but longitudinal movement of levers 12 relative to blocks 15 is permitted.

Levers 12 are rocked about their pivotal axis on bearings 14 by the engagement of a pin 16 on one lever in the groove of a disc cam 17 (i.e. the vertical cam). This cam is secured on a shaft 18, supported in the framework 6 and driven through gearing 19 from the driving means to the sewing machine 5. l 7

Movement ofthe carriage 8 in the horizontal direction is effected by the movement engages in a vertical walled channel provided on the underside of the carriage 8' and extending in its other (vertical) direction of movement. As best seen in Figure 4, vertically disposed rollers 21, rotatably mounted in the head 20, project from twoopposite faces of the head and engage thewalls of the channel in the carriage. The carriage is thus constrained to partake of the horizontal movements of the head, but can move freely in a vertical direction relative to the head and can also move vertically (with respect to Figure 4) relative thereto. The other two side faces of the head 20 carry vertically projecting trunnions, formed by the end of a pivot pin 22, which are pivotally received in the forked upper end of an operating arm 23a of a link pantograph designated generally by the reference 23.

The link pantograph 23 comprises the operating arm 23a to one end of which ishinged a first link 23b. A short distance from this end of the arm 23a is hinged a second link 23c. The outer ends of these links are jointed by a third link 23d. The three links 23b, and d and the end portion of the arm 23a form a parallelogram. The joint between the first and third links is fixed tothe framework 6 of the machine as the fulcrum, indicated at 33, of the pantograph. At a point indicated generally at 34 on the second link 23c lying on a line joining the fulcrum 33, and the outer end of the arm 23a is. the end remote from the link arrangement, the pantograph pickup point is arranged. Owing to the properties of such a pantograph any movement of the pick up point will be reproduced an an enlarged scale by the outer end of the operating arm.

The pick up point 34 of the link pantograph is mechanically coupled by a transfer means comprising two links. 41 and 42, pivotally connected at their outer ends to the ratio adjusting mechanism indicated generally at 40 and which will be described in detail later, to a slide 36 mounted for horizontal movement upon stationary guide rods 37 forming part of framework 6. Slide 36 carries a stud 38 which engages in the helical groove of a cylinder cam 39 (the horizontal cam) fast upon the shaft 18. Rotation of shaft '13 thus causes both vertical movement of the carriage 8, through the action of cam 17 and levers 12, and horizontal movement of the carriage, through cam 39, slide 36, links 41 and 42, pantograph 23 and arm 23a.

The inner end of the link 41 is connected by means of a pivot pin 43 tothe slide 36. The outer end of link 41 is pivotally connected to the upper end of a rocking lever 44 by means of a fixed fulcrum pin 45. The lever 44 is pivotally mounted at its lower end in a bracket 46, attached to the frame 6 of the machine, by means of a pivot pin 47 to which said lever 44 is fixedly secured. Thus horizontal movement of slide 36 causes horizontal movement of link 41 which rocks lever 44 about its pivot pin 47. Movement of the upper end of lever 44 is transferred to the pick up point of the pantograph by means of the link 42. To this end, the inner end of link 42 is pivotally connected to the pick up point 34 of the pantograph by means of pivot pin 43, sleeves 4? on either end of this pin being slidably engaged in slotted apertures 50 formed in a bracket 51 attached to the slide 36. By slidably mounting the sleeves 49 in the apertures 50 in this way the movement of the pantograph linkage is substantially stabilized. The outer end of link 42 is connected to lever 44 via a pivot pin 52 which can be adjusted vertically (Figures 3 and up and down the lever 44. If the axis of pin 52 is further away from the axis of pin 47 than is the axis of pin 45 then the lever 44 will magnify any motion of the cam stud 38 before it is passed to the pantograph. Conversely if the axis of pin 52 is nearer to the axis of pin "47 than is the axis of pin 45, the motion of cam stud 38 will be reduced before it is passed to the pantograph.

Vertical adjustment of pivot pin 52 is effected by of a block or head 20- which I V V '4 means of a knob 53 which is secured to the upper end of a threaded shaft 54 and prevented from movement axially relative to lever 44. This shaft 54 threadably engages a cross head 55 to which the inner end of pin 52 is attached, the cross head 55 being slidably engaged in a vertically wall channel 56 formed in the lever 44. This rotation of the knobrfifiimoves the cross head 55 in a vertical direction up and down its channel 56. On the outer threaded portion of pin 52' is provided a lock nut 57 which, when tightened pulls the member 55 to the right (Figure 6) against the walls ofits channel and prevents excessive thrust being placed on the shaft 54. A scale and index pointer 58 are provided to facilitate adjustment of the ratio adjusting means 40.

It is usual in sewing machines for sewing mens collars to arrange for the final stitch always to be in the same position. Ratio adjustment by the means just described will displace both the starting and final stitch. To compensate for this a datum adjuster is interposed between the pivot pin 52 and the link 42. The datum adjuster is indicated generally at 59 and comprises a bearing block 60 which receives the pivot pin 52 and which is mounted in the bifurcated end portion of link 42 so as to be slidable relative thereto. Attached to the outer end of block 69 is a threaded shaft 61 and an adjusting wheel 62 is threadably engaged on this shaft between an end plate 63 for the link and an end cap 64. Rotation of the wheel 62 causes movement of the bearing block to the left or right (Figure 4) thus either increasing or decreasing respectively the effective length of link 42. A lock nut 65 is provided on the outer end of the threaded shaft 61.

From the foregoing it will be evident that rotation of knob 53 shifts the pivot pin 52, bearing block 60 and the bifurcated end of link 42 lengthwise of lever 44 (Figs. 4, 6 and 7) thereby changing the ratio between horizontal and vertical movement. Likewise rotation of wheel 62 shifts the bearing block 60 lengthwise of link 42 thereby effecting the datum adjustment.

I claim:

1. In apparatus for guiding a workpiece under the needle of a sewing machine along a predetermined stitching line, the combination comprising, a frame, a work supporting carriage on said frame for motion in a plane, two drive means on said frame for moving said carriage in each of two mutually perpendicular directions in said plane respectively, transfer means interposed between said drive means and carriage for transferring the movement produced by each of said drive means to said carriage, and ratio adjusting means included in one of said transfer means for adjustment of the ratio between the movement produced by the drive means for said one transfer means and the resultant movement between said carriage and said needle.

2. Apparatus according to claim 1, in which said one transfer means comprises a cam follower, a first link pivotally connected at its inner end to said cam follower and extending to said ratio adjusting means, and a second link extending from said ratio adjusting means in the direction of said first link and substantially parallel thereto, the inner end of said second link being pivotally connected to means for moving said carriage in one of said two directions.

3. Apparatus according to claim 2, further comprising a rocking lever, said rocking lever being pivotally connected at its lower end to the frame of the machine and at its upper end to the outer end of said first and second links, said first link being pivotally connected to said rocking lever by means of a pivot the axis of which is fixed relative to said rocking lever, while said second link is pivotally connected to said rocking lever by a pivot the axis of which is movable, by means of said ratio adjusting means, in the same plane as the axis of the pivotal connection between said rocking lever and said first link and in a direction perpendicular to said secondlink. a

4. Apparatus according to claim 3, in which said ratio adjusting means includes a cross head and a pivot pin secured to the crosshead, said pivot pin forming the pivotal connection between said second link and said rocking lever; in which said rocking lever has a vertically,

walled channel for-med therein, said crosshead being adapted for sliding movement in said direction in said vertically walled channel formed in said rocking lever; and in which a first shaft threadably engages said cross head whereby, rotation of said first shaft will cause movement of said cross head vertically along said channel to vary the ratio between the movement produced by the drive means for said one transfer means and the resultant movement between said carriage.

5. Apparatus according to claim 4, further comprising a knob which is fixedly secured 'to the upper end of said first shaft and which is prevented from movement axially relative to said rocking lever, whereby rotation of said first shaft can be eifected.

6. Apparatus according to claim 3, further comprising a datum adjuster for varying the distance between the pivotal connection'between said rocking lever and said second link and the pivotal connection between said second link and said means for moving said carriage in said one direction.

7. Apparatus according to claim 4, further comprising a datum adjuster for varying the distance between the pivotal connection between said rocking lever and said second link and the pivotal connection between said second link and said means for moving said carriage in said one direction, said datum adjuster including a bearing block for receiving said crosshead pivot pin, said block being mounted in the outer end of said second link so as to be capable of movement longitudinally of said second link, a second shaft secured at its inner end to said block, and an adjusting wheel threadably engaged on said second shaft and which is prevented from movement axially relative to said second link, whereby rotation of said wheel causes movement of said block relative to said second link, for varying said distance.

8. Apparatus according to claim '2, in which said means pivotally connected to the inner end of said second link for moving said carriage in said one direction comprises a link pantograph, said pantograph having a fixed pivot point secured to the frame of the machine, said pivotal connection between said second link and said means for pick up point of the pantograph.

References Cited in the file of this patent UNITED STATES PATENTS 268,804 Keith et al Dec. 12, 1882 875,614 Parkes Dec. 31, 1907 2,597,686 Turner et a1. May 20, 1952 2,624,302 Meister Ian. 6, 1953 2,672,110 Christopherson Mar. 16, 1954 2,682,239 Klema et al June 29, 1954 2,684,651 Bihaly July 27, 1954 2,724,896 Mich Nov. 29, 1955 2,734,271 Moriarty Feb. 14, 1956 2,806,440 Schenkengel Sept. 17, 1957

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