US3272161A

US3272161A - Presser foot actuating mechanisms for sewing machines

Info

Publication number: US3272161A
Application number: US309018A
Authority: US
Inventors: Otto R Haas
Original assignee: United Shoe Machinery Corp
Current assignee: United Shoe Machinery Corp
Priority date: 1963-09-16
Filing date: 1963-09-16
Publication date: 1966-09-13
Anticipated expiration: 1983-09-13

Description

p 13, 1966 o. R. HMS 3,272,161

PRESSER FOOT ACTUATING MECHANISMS FOR SEWING MACHINES Filed Sept. 16, 1963 5 Sheets-Sheet 1 Inventor P 13, 1955 o. R. HAAS 3,272,161

PRESSER FOOT ACTUATING MECHANISMS FOR SEWING MACHINES Filed Sept. 16, 1963 5 Sheets-Sheet 2 0 Z0 40 60 80 0 I20 I40 16 I50 2.0 E20 2'10 260 260 300 320 40 560 mznsuama UPPER at LOWER LOCK Sept. 13, 1966 o. R. HAAS 3,272,161

PRESSER FOOT ACTUATING MECHANISMS FOR SEWING MACHINES Filed Sept. 16, 1963 5 Sheets-Sheet 5 Sept. 13, 1966 Filed Sept. 16, 1963 0. R. HAAS PRESSER FOOT ACTUATING MECHANISMS FOR SEWING MACHINES E 0 E 240 290 E80 b am 340 5 Sheets-Sheet 4 THREAD 0 2o an no :20 mo 1 mznsunme CLOSE I UPPER LOWER LOCK OPEN Sept. 13, 1966 o. R. HAAS 2,

PRESSER FOOT ACTUATING MECHANISMS FOR SEWING MACHINES Filed Sept. 16, 1963 5 Sheets-Sheet 5 166 O 164 J66 I United States Patent 3,272,161 PRESSIER FOUT ACTUATING MECHANESMS FOR SEWING MACHINES (ltto R. Haas, Wenhani, Mass., assignor to United Shoe Machinery Corporation, Boston, Mass, a corporation of New Jersey Filed Sept. 16, 1963, Ser. No. 3tl9,18 11 Claims. (Cl. 112-38) This invention relates to improvements in shoe outsole stitching machines and more particularly to presser foot actuating mechanisms for clamping work in sewing position in such machines, examples of which are disclosed in United States Letters Patent No. 1,169,909, granted February 1, 1916, upon application of Fred Ashworth, No. 1,337,992 granted April 27, 1920, upon application of Fred Ashworth No. 2,271,611, granted February 3, 1942, upon application of Fred Ashworth and Carl F. Whitaker, and No. 2,148,197, granted February 21, 1939, upon application of the present inventor.

In the machines of the patents above referred to the work is clamped at the operating point of a set of stitch forming devices by a presser foot actuated toward and from the work engaging surface of a work support to prevent displacement of the work and to release the work as the work is fed in each stitch forming cycle of machine operation. To accommodate different thicknesses of work ranging from a small fraction of an inch to slightly more than an inch, the presser foot is oscillated toward and from the work support by means of a cam actuated lever and a differential mechanism comprising a floating lever connected to the cam lever at one point, to a releasable lock at another point, and to the presser foot at a third point. The lock acts to release the foot momentarily away from and into re-engagement with the work under the influence of a spring, so that it may assume a new clamping position in each sewing cycle. The initial position assumed when the presser foot reengages the work under the influence of the spring determines the amount of pressure exerted in clamping the Work.

One difliculty with a presser foot mechanism acting in this manner is that a relatively complex lock is required, which is both expensive to manufacture and critical to control, especially in the presence of accumulated dust, oil and other contaminants usually found in areas where such machines are utilized. If the presser foot fails initially to engage the work securely or bounces under the influence of the spring from its position of re-engagement with the work while the lock is becoming effective, the work may not be clamped properly. Furthermore, other operations, such as thread measurement also are dependent upon the initial clamping position of the presser foot on the work, so that if the clamping action is improper, the amount of thread measured will be incorrect and the accuracy of seam formation may be affected adversely.

The present invention has for an object the provision of a presser foot actuating mechanism for an outsole stitching machine, in which there is no need for a complicated lock, so constructed as to be influenced by the presence of dust or contaminating materials. More specifically, other objects are to provide a presser foot actuating mechanism which does not depend upon the position initially assumed by the presser foot as it re-engages the work under the influence of a spring to determine how much pressure will be exerted in clamping the work or how much thread is measured for each stitch being formed.

To the ends noted, the invention resides in a shoe outsole stitching machine having a frame, stitch forming devices in the frame, a main sewing shaft for actuating the stitch forming devices, a work support, a presser foot and mechanism driven by the sewing shaft for actuating the presser foot to clamp and release the work, 'in which machine a presser foot lever actuated by a cam on the sewing shaft is connected through a train of adjustable connections between a cam lever and the presser foot lever, the adjustment of the connections being accomplished by a light weight feeler acting independently of the initial position assumed by the presser foot while re-engaging the work periodically throughout the insertion of a seam. By the use of a feeler acting independently of the presser foot the thickness of the work may be calipered continuously by the feeler to change the adjustment of the presser foot actuating connections, so that a more reliable, accurate and sensitive control for the foot is obtained independently of the mass of the presser foot or its actuating connections.

The invention is equally applicable to any machine whether the machine acts to feed the work for performing an operation on work in a step-by-step manner or continuously without interruption and whether the work is fed by an awl or by joint movements of the work support and presser foot acting as a clamp, or by both awl and clamp for a continuous feeding movement of the work. In any type of operation performing machine, regardless of the nature of work feed employed, the feeler may engage the work continuously, so that accurate response in the position of the presser foot is obtained or the feeler may disengage the Work intermittently for brief intervals in order not to interfere with work feed or to abrade or otherwise injure the surface of the work as the result of relative frictional movement between the work and the feeler. Even with brief intervals of disengagement a more accurate calipering action is possible by using an independent feeler than where an almost instantaneous engagement and locking action is required as a presser foot is finding its own initial position in prior machines.

The use of a feeler movable independently of the presser foot is of further benefit not only because it avoids the necessity for the presser foot to find its own initial position on the work under spring action before clamping it but also because the separate calipering action of the work requires no more than a relatively light pressure, so that the feeler may be arranged to adjust reliably the measurement of thread for each stitch at a time and with a pressure on the work, which is a small fraction of that needed for the presser foot clamping action. To secure heavy work the presser foot is required to engage and clamp the work with relatively heavy pressure at critical times in each stitch forming cycle and the work frequently exhibits wide variations in compressability and resiliency, so that thread measurement in prior machines is often affected adversely from this cause.

These and other features of the invention, as hereinafter described and claimed, will be apparent readily to those skilled in the art from the following detailed description, taken in connection with the accompanying drawings in which:

FIG. 1 is a view in front elevation of a portion of a shoe outsole stitching machine head embodying the features of the present invention;

FIG. 2 is a detail view in right side elevation of presser foot actuating and thread measuring mechanisms, show ing the positions of the parts while operating upon relatively thin work in the machine of FIG. 1;

FIG. 3 is a detail plan view of a work calipering feeler for adjusting the movements of a presser foot showing its relation along the line of work feed with a needle and an awl employed in the machine;

FIG. 4 is a detail view in right side elevation and on a somewhat enlarged scale of a portion of a presser foot adjusting cam in the mechanisms of FIG. 2;

FIG. 5 is a time chart showing relative movements of the thread measuring mechanism including a pair of thread locks employed therein;

FIG. 6 is a right side elevation similar to that of FIG. 2, illustrating the position of the parts while operating upon relatively thick work;

FIG. 7 is a sectional plan view of a step type awl feed mechanism employed in the machine, as seen from the line VIIVII of FIG. 6;

FIG. 8 is a view in front elevation of portions of a clamp feed machine utilizing a feeler controlled presser foot;

FIG. 9 is a time chart showing the relationship of thread measuring mechanism and upper and lower thread locks employed therein when utilizing a clamp feed in the machine, as illustrated in FIG. 8;

FIG. 10 is a modified form of the invention, illustrating in right side elevation portions of a feeler controlled presser foot mechanism to be utilized in connection with the machine of FIG. 1, in which the feeler is moved away from the work during back feed of a work feeding awl; and

FIG. 11 is a detail sectional view on a somewhat enlarged scale, showing a frictional device employed to stabilize a thread measuring mechanism employed in the modified form of the invention illustrated in FIG. 10.

Except as hereinafter described, the machine illustrated in the drawings is generally the same in construction, arrangement of its parts and mode of operation as the machines disclosed in Patent No. 1,169,909 or No. 2,271,- 611 above referred to. More specifically, the machine is provided with a stitching head having a frame 12, in which is mounted a pair of main shafts, one being indicated at 14, for actuating lock stitch forming devices including a curved hook needle 16, a curved work feeding awl 18, a needle looper 20, a thread finger 22, a take-up 24, a shuttle 26, containing a case 28 for a supply of locking thread, and a pair of thread locks, commonly identified as front and

rear locks

30 and 32, between which the needle thread is acted upon by a thread measuring pulloif 34. To measure the proper amount of needle thread for each stitch in accordance with the thickness of the work being operated upon the pull-off 34, which is given a stroke during each sewing cycle regulated by a needle thread measuring mechanism, the pull-off acts between a pair of fixed thread guides 36 (FIG. 2). From the front lock the thread is carried upwardly over a guide roll 38 downwardly beneath the take-up 24 and upwardly to the needle looper 20.

In the machine of the prior Patent No. 1,169,909, the work is clamped during the formation and completion of each stitch between the work engaging surfaces of a fixed work support 40 and a vertically movable presser foot 42. The presser foot is secured to the forward end of a presser foot lever 44 actuated by a self-adjusting cam actuated mechanism, the adjustment of which is accomplished by the initial position assumed by the presser foot under the yielding action of a spring during a very brief interval of time in each sewing cycle. During the interval of the spring action the presser foot is left free to engage the work, after which the presser foot quickly is locked securely in position and usually is given an additional squeezing movement to compress the Work forcibly, thereby clamping it against the work support. Since the clamping force of the presser foot on the work frequently may reach as high as several hundred pounds the self-adjusting action of the presser foot mechanism by initial engagement with the work has always presented a critical problem. This is particularly true when it is realized that the self-adjusting action of the presser foot mechanism not only determines the amount of additional work clamping movement imparted to the foot but also controls the action of the thread measuring mechanism. If either the presser foot mechanism by itself or with the thread measuring mechanism are improperly adjusted, obviously the formation and tightness of stitches in a seam will be affected adversely. If there is any tendency for the presser foot mechanism adjustment to be retarded or for the presser foot to bounce as the result of resiliency in the work, irregular stitches are certain to result or parts of the presser foot mechanism may be strained unduly and subjected to pressures beyond which they are intended. These conditions are complicated still further by the movement of the presser foot in squeezing the work. Such squeezing movement can be adjusted manually and may indirectly affect the thread measuring mechanism, so that whenever the squeezing movement is changed the thread measuring mechanism also requires readjustment.

In accordance with the present invention the presser foot mechanism is so arranged that it no longer is necessary for it to adjust itself and instead reliance is placed upon a movable light weight feeler separate from the presser foot and arranged to engage the work more or less continuously between the work support and presser while being operated upon by the stitch-forming devices. By the use of a light weight feeler arranged in this way an instantaneous determination of the work thickness is possible at practically any time during each sewing cycle, so that proper adjustment of other dependent devices are possible from the feeler and the mechanisms for actuating the dependent devices, such as those for measuring thread need no readjustment and no compromise or modification in the program of timing with relation to the various stitch-forming functions is necessary.

Under some circumstances it may be desirable to impart to the feeler movement away from the work on the work support, so that the feeler will not drag along the work frictionally, either in a manner to abrade the work or otherwise to retard the feeding movement. Even with these restrictions the feeler still is free to find its own position on the work with a relatively light yielding force for a duration of time in each sewing cycle which is conducive to accuracy in calipering action on the work. Accordingly, the entire stitch-forming cycle of operations is improved with better results in a completed seam inserted. Also, the necessity is avoided for finding a satisfactory presser foot lock, which will be secure under all conditions, quick to respond in locking or unlocking the parts, durable in use and inexpensive to manufacture.

The work calipering feeler is indicated at 46 (see FIG. 2) and comprises a light weight vertical rod slidable freely along a guide in the form of a block 48 secured to an extension on an arm of a lever 50 (see also FIG. 7) comprising a portion of a mechanism for imparting a feeding movement to the awl, as more fully described in the Ashworth patent referred to. The feeler 46 is urged yieldingly at all times against the upper surface of a work piece disposed between the work support and the presser foot, so that it maintains a continuous calipering action on the work, changing its position immediately in accordance with a varying thickness of the work.

The lower end of the feeler 46 engages the work within the U of a U-shaped lower end on the presser foot 42. In order not to interfere with the operation of the needle 16 and the awl 18 the feeler engages the work in advance of their locations, as illustrated in FIG. 3, and the awl acts to form a perforation for the needle and then moves the work sufficiently to bring the perforation into line with the needle path. By reason of the block 48 carried by the feed lever 50 the spacing in the direction of work feed between the feeler 46 and the awl 18 is kept constant, so that no possibility of interference exists. In this way it is possible to transfer an indication given by the feeler 46 to the presser foot actuating mechanism and to the thread measuring mechanism in accordance with the thickness of the work, adequately in advance of the time in each sewing cycle when the thread is drawn into the work to insure use of the measuring thread exactly at the point where the work is calipered. Thus, no delay occurs in delivering measured thread to the stitch-forming devices it and a much more accurate thread measurement is possible than heretofore.

The adjustable presser foot actuating mechanism comprises a link 52 pivotally connected between the presser foot lever 44 and one of a pair of concentrically pivoted

levers

54 and 56. The

levers

54 and 56 are loosely fulcrumed concentrically on a shaft 58, the lever 54 being provided with a follower 60 engaging a presser foot cam 62 on a sewing shaft 64 and one arm of the lever 56 being pivotally connected to the link 52.

The

levers

54 and 56 comprise mechanism for actuating the presser foot to clamp and release the work supported on the work support body and between the levers there is a train of adjustable connections arranged to change the relationship between the levers as the thickness of the work varies between successive stitches. To adjust the connections between the

levers

54 and 56 the work calipering feeler 46 acts directly on the connections.

The train of adjustable connections between the

levers

54 and 56 consists of a cam plate 66 rotatably mounted by means of a pin 68 on a downwardly extending arm of the lever 56. The cam plate has an arcuate slot 7!) disposed in eccentric relation to the axis of the pin 68, the arrangement being such that the radius of the slot 70 in a clockwise direction constantly decreases and in a counterclockwise increases. The slot 70 is engaged by an arcuate slider 72 pivotally supported on a downwardly extending arm of the lever 54. The changing radius of the cam slot 70 is insuflicient to impart movement of the cam plate about its pin 68 when force is applied between the levers 54- and 56. However, the cam plate may be shifted about the pin 68 by a relatively light force exerted by the feeler 46.

To connect the feeler 46 with the cam plate the upper end of the feeler has pivoted to it a handle link 74 by a stud 76 fixed in a forwardly extending arm of a threearrn lever 78 fulcrumed on a screw 80 secured, in turn, to the frame 12 of the machine. To insure that the feeler will engage the work continuously during operation of the machine the forward arm of the lever 78 is engaged by an upwardly extending yieldable rod 82 pressing downwardly on the forwardly extending arm of the lever 78. To enable the downward pressure on the feeler to be adjusted the rod 82 is surrounded at its upper end by a threaded sleeve 84 having a knurled collar and the lower end face of the sleeve presses against a resilient spring 86 compressed between the sleeve and a head on the lower end of the rod. The sleeve 84 is threaded into an opening in the frame 12 and is secured in adjusted position by means of a check nut 88.

When the feeler 46 is raised it moves the cam plate 66 through the action of the lever 78 and an arcuate link 90 pivotally connected between the lever 78 and the cam plate. When the feeler is raised manually by the handle link 74- it disengages the presser foot also from the work. Assuming that the lever 54 remains stationary, as when the machine is brought to rest, upward movement of the feeler causes the arcuate link 96 to move downwardly and the cam plate 66 to move in a direction, in which the slider 72 engages a smaller radius portion of the cam slot '70, thus drawing the lower end of the lever 56 toward the lower end of the lever 54-. In so doing the upper end of the lever 56 is moved toward the right, pulling on the link 52 and raising the presser foot. If the feeler 46 is lowered a reverse movement of the cam plate 66 takes place and the presser foot 44 is brought into engagement with the work, the force of the spring 86 normally being sufficient to produce the work engaging movement of the presser foot. By the spring 86 the feeler is kept constantly in engagement with the work, so that the position of the presser foot is always maintained in proper relation to the work.

The action of the cam follower 60 during rotation of the cam 62 produces a movement of the presser foot toward or away from the work in timed relation to the movements of the other work engaging and stitch forming devices in the machine, the lower end of the feeler being slightly rounded to avoid abrasion or marking of the work. Under normal conditions any movement of the feeler toward or away from the work support 40 produces a similar movement in the presser foot, except for a periodic work clamping and releasing movement imparted to the presser foot by the cam 62.

When the machine is stopped, upward movement of the handle link 74 causes both the feeler 46 and the presser foot 44 to be raised together in order to release the work and to enable replacement with a new work piece. The positions of the parts with the feeler and presser foot raised are shown in FIG. 6, while the corresponding positions with the feeler lowered are shown in FIG. 2.

To insure that the feeler 46 will in no way impede the feeding movement of the work when the work is fed by engagement of the awl 18, the guide block 48 for the feeler is moved with the work each time it is fed in such manner that the lower end of the feeler has a slightly greater movement in the direction of work feed than the work itself. This feed movement of the feeler is the result of a swinging movement at the distal end of the lever 50 which is fulcrumed on a shaft 92, shown in FIG. 7. Between the distal and fulcrum ends of the lever 50', it is provided with a projection which engages one end of a sliding stud 94 on which the curved work feeding awl 18 is mounted.

To permit the feeler 46 to move in the direction of work feed the handle link 74 has a fork across which is fixed a pin 95 and the upper end of the feeler 46 is mounted for sliding movement on the pin 95 (FIG. 1). By reason of the greater work feed movement imparted to the feeler than to the awl there is no possibility for engagement between the feeler and the work to retard work feed. During back feeding movement of the awl 18 while the work is securely clamped there is no likelihood that any reverse feeding effort exerted on the work will overcome the grip of the presser foot and work support. In other respects the work feeding mechanism is the same as disclosed in the Patent No. 1,169,909.

To enable the feeler and the presser foot to be raised from engagement with the Work automatically an upward-1y extending arm of the lever 78 is pivotally connected to a rearwardly extending link 96, the rearward end of which is similarly connected to an arm on a lever 98 in an auxiliary operation performing mechanism. The auxiliary operation performing mechanism acts through a link 99 and other connections during the final few degrees of rotation of the sewing shaft 64- in the manner disclosed in Patent No. 1,337,992 to raise the presser foot and the feeler together from engagement with the work.

To insure that the amount of thread measured by the measuring mechanism corresponds to the length required for each stitch in a seam regardless of the thickness of the work, the pull-off 34 is in the form of an angularly bent arm rotatable about a fixed shaft 100. The pull-off arm has formed in it a slot 1112 engaged by a roll on a pin 1114 mounted in a lower arm of a lever 106 rotatable on a fulcrum stud 107. In its upper arm the lever 106 has an arcuate slot 108, in which is slidably mounted an extending end of a pivot 110. The pivot 110 is secured in one end of a horizontal link 112, the other end of which is similarly connected at 113 to a downwardly extending arm of a vertical lever 114 fulcrumed on a shaft 116 and provided at its upper end with a roll 118 engaging a cam slot 120 in a cam 122, the cam being secured to the sewing shaft 64.

When the position of the feeler 4-6 is shifted by changes in the thickness of the work the angle of the plate 66 on its mounting pin 68 is made to correspond with the position of the feeler. At the same time the position of the pin 110 in the slot 108 is shifted through a connection 8 link 124 pivot-ally connected to the lever 78 concentrically with the link 90. Thus, the effective length of the upper arm of lever 106 is changed and the amount of movement imparted to the pull-off arm 34 by the cam 122 is increased or decreased in accordance with the thickness of the work.

The advantage of a continuous calipering action by the feeler on the work for the purpose of adjusting the thread measuring mechanism is illustrated in FIG. 5. In this figure the upper curve labeled THREAD MEASURING indicates that it is relatively easy to provide a slow uniform movement in the pull-off arm 34 between 20 and 320 of rotation in the main sewing shaft 64 and a. maximum time period of 300 may be utilized in actuating the pull-off arm. During this period the upper lock 30 is closed and the lower lock 32 (FIG. 2) is held open, so that a reliable thread measuring action may take place without any sudden impulse being imparted to the thread. The timing is illustrated by the curves labeled UPPER AND LOWER LOCKS. Accordingly, a much more uniform thread measuring action can be accomplished than where the thread must be measured in a briefer interval. The only time in which the upper thread lock 30 needs to be held open is during the last 20 of rotation in the sewing shaft 64 while each stitch is being set by tensioning the thread with the take-up 24.

The relative positions of the needle 16, awl 18 and feeler 46 along the line of a seam, as best shown in FIG. 3, the work being fed from right to left. From this figure it is apparent that the feeler 46 engages the work approximately a stitch length in a advance of the point of operation of the needle and awl, as the work moves in the direction of feed, indicated by the arrow 125. The feeler is thus able to caliper the work before the effective thickness is modified by the penetrating action of either the needle or awl. Also, during each sewing cycle, in the illustrated machine, the feeler engages the work in advance of the needle and awl, regardless of the type or shape of presser foot employed. For this reason the thread measuring mechanism is capable of being adjusted in ample time to furnish a length of measured thread for a stitch inserted at the same location at which the work was calipered rather than at a position one or more stitches beyond the calipering location, as occurs in prior machines in which the presser foot must perform its own work oalipering action. The use of the present presser foot mechanism with a work calipering feeler is of advantage not only in the operation of a sewing machine having a work feeding awl but is also of benefit in a machine, in which the work is fed by a clamp, as in the machine illustrated in Patent No. 2,271,611, above referred to.

An application of a feeler adjusted presser foot and thread measuring mechanisms to a clamp feed machine is illustrated in FIGS. 8 and 9. In the case of a clamp feed machine the work calipering feeler is maintained in a fixed position along the line of a seam and the work is fed while it is being gripped in the clamp, comprising a work support 126 and a presser foot 128, both of which are mounted in a carrier 129 for moving them while clamping the work. In a clamp feed machine the needle indicated at 130, and the awl at 132, are mounted for oscillating movement in a common fixed path toward and from the work and no feeding movement need be imparted to either one. The feeler, indicated at 134 in this machine, is positioned close to the common path of the needle and awl and is slidable for movement toward and from the work within a guide 136 fixed to the frame of the machine. At its upper end the feeler 134 is pivotally connected to a handle link 138, which, in turn, is similarly connected to a fork on the forward end of a three-armed lever 140, corresponding to the lever 78 shown in FIGS. 1 and 2. In this case the lever 140 is acted upon by a spring pressed rod 142 similar in construction to the rod 82in FIGS. 1 and 2.

With the use of the calipering feeler 134 in a clamp feed machine, in which it is guided in fixed relation to the needle and awl, advantages similar to those in an awl feed machine are obtained. By reference to FIG. 9, it is evident that a thread measuring movement of the pull-off arm, as illustrated in the uppermost curve labeled THREAD MEASURING, may take place during a full 300 time period of rotation for the main sewing shaft. The upper and

lower thread locks

30 and 32 are actuated during the times indicated by the curves UPPER AND LOWER LOCKS. An added advantage in the use of a clamp feed machine results in maintaining the length of feed more uniformly than with an awl feed machine, the rigidity of the work support and presser foot being greater than that of an awl. In this way closer conformity with the requirements is possible because where the feed is nonuniform, variations in thread requirements are bound to occur.

In the operation of the work calipering feeler in either an awl or clamp feed machine, as thus far described, the feeler is in continuous engagement with the work during operation of the machine. In order to avoid retarding the feed of the work by reason of frictional engagement with the feeler it may be desirable to disengage the feeler from the work during feeding movement of the awl in an awl feed machine or during back feeding movement of the clamp in a clamp feed machine. To these ends the machine of FIGS. 10 and 11 provides mechanism for actuating the work calipering feeler in this way. The disengagement of the work by the feeler in a machine having a feed of either type should occur while the presser foot releases its grip on the work. Thus, the time of disengagement of the work calipering feeler would be the same in the two types of machine.

Referring more particularly to FIGS. 10 and 11, the machine illustrated is of the awl feed type, as shown in FIGS. 1 to 7, inclusive, while the general arrangement of the operating parts in the presser foot and thread measuring mechanisms are also the same. The principal difference between the machine of FIGS. 1 to 7, inclusive, and that of FIGS. 10 and 11 is in the arrangement of the cam plate forming the train of adjustable connections between the two concentrically mounted actuating levers 54 and 56. In the machine of FIGS. 10 and 11 these presser foot connections have been changed in their general arrangement.

As shown in FIG. 10, the machine is provided with a presser foot lever 144 pivotally mounted on a shaft 146 in a fixed portion of a machine frame 148. To urge the presser foot into engagement with a work piece carried by the work support a downwardly extending arm of the lever 144 is connected with one end of a resilient tension spring 150, the other end of which is attached to a pin 152 on the machine frame 148. The spring not only causes the presser foot to move downwardly into engagement with the work but also causes the feeler to be pressed yieldingly against the work through reaction on the train of adjustable connections.

The work calipering feeler in the machine of FIGS. 10 and 11 is indicated at 154 and is similar in construction to that of the machines in FIGS. 1 to 9, inclusive. The feeler 154 consists of a vertical rod slidingly mounted in a guide block 156 secured to the distal end of a feed lever 158, similar to that indicated at 50 in FIG. 7, the lever intermediate its ends having a projection to actuate an awl supporting stud 160. The work support is indicated at 162 and is secured to the machine frame.

The work calipering feeler 154 is pivotally connected at its upper end to a handle link 164, which, in turn, is pivotally connected to a three-armed lever 166 fulcrumed at 168 on the machine frame 148. A rearwardly extending arm of the lever166 is connected through a link 170 to a pivot 172 on a cam plate 174, having a generally horizontal arcuate slot 176 within which is loosely guided a slider pin 178. To provide adjustable presser foot connections the slider pin 178 is secured to one arm of a lever 180 fulcrumed on a shaft 182 concentrically fulcrumed with a second lever 183, a forwardly projecting arm of which carries a pivot 184, the cam plate 174 being rotatably mounted on the pivot 184. A rearwardly extending arm of the lever 183 supports a cam roll 186 engaged by a cam on a sewing shaft 188, similar to that in the machines of FIGS. 1 to 9, inclusive. As in the machines described the connections between the work calipering feeler 154 and the presser foot lever 144 through the cam plate 174 cause the feeler and presser foot to move together, except when the lever 183 is actuated by the cam on the sewing shaft.

By reason of the arrangement of the cam slot 176 in the plate 174 at approximately a horizontal position rather than a vertical one, movement of the cam plate in a vertical direction causes the feeler 154 also to move vertically rather than to remain stationary, as in the previously described machines. The action of the spring 150 through the connections between the presser foot and the feeler exerts a relatively light force on the feeler, so that the spring causes the presser foot to engage the work with a heavy pressure, whereas the previously described feeler may engage the work with a heavier pressure.

The action of the lever 183 in raising the presser foot from engagement with the work causes the feeler 154 to be pressed against the work and then to impress a swinging movement on the cam plate 174 about its mounting pivot 184, thus changing the adjustment of the mechanism. If the thickness of the work remains the same from one stitch to another no movement of the cam plate about its mounting pin 184 occurs.

The cam for actuating the roll 186 on the lever 183 is so shaped that it causes the feeler to disengage the presser foot from the work, so that the work may be fed by the awl without retarding the work by engagement with the feeler. The feeler is moved into engagement with the work just before the presser foot, so that it may caliper the thickness of the work before it is compressed by the presser foot. Thus, the feeler is given -at least one complete reciprocation toward and from the work during each sewing cycle.

In order to adjust the measurement of thread in accordance with the thickness of the work in the machine of FIGS. 10 and 11, the feeler acts through the link 170 and a bar 190 pivotally supported on the pivot 172 and having a lower end of reduced diameter sliding within a bore formed in a guide rod 192 with a telescoping engagement. The lower end of the rod 192 is pivotally connected by a pin 194 to the forward end of a link 200 actuated by a cam lever 20 2 through a pivotal connection 204. The pin 194 connecting the

links

192 and 200 is slidingly mounted in an arcuate slot 206 in a lever 208. The lever 208 is fulcrumed on a fixed shaft 210 and has secured in a downwardly extending arm a pin 212. A roll on the pin 212 is slidingly engaged in a vertical slot formed in a pull-off arm 214, which is rotatable on a shaft 216 secured in the machine frame. The pulloff arm 214 acts on the thread between two guide eyes 218 in the manner explained in the above-described machines and pull-off action is adjusted by connections including the

bars

190 and 192.

The

bars

190 and 192 are connected together through a limited lost motion joint by reason of their telescoping engagement. To limit the lost motion between the bars the reduced end of the bar 190 carries a cross pin 22!) extending through slots 222 at opposite sides of the bar 192. The length of the solts 222 is suificient to enable the feeler 154 to be reciprocated freely toward and from the work without actuating the bar 192 so long as the feeler always re-engages the work in the same position. When the position of the feeler is changed from one stitch to another by reason of a variation in the thickness of the work the cross pin 220 is pressed by one end of 10 the slot 222 and moves the bar 192 to adjust the thread measuring movement of the pull-off 214.

To retain the bar 192 in its adjusted position when no movement is imparted to it, it is surrounded 'by a friction guide consisting of a pair of semicylindrical fiber pieces 224 (see FIG. 11). The fiber pieces 224 are supported in a pair of grooves, one of which is formed within a support block 226 having a cylindrical projection and the other of which is formed within a cap plate 228 secured yieldingly in co-operative relation with the block 226, in order to impart friction to the bar 192.

To enable the friction on the bar 192 to be regulated the block and the cap plate are perforated to receive a bolt 230, around which is coiled a spring 232 compressed between the cap plate 228 and a thumb nut 234 threaded on the bolt 230. During operation of the machine as the lever 208 swings about the shaft 210 the friction device, comprising the block 226 and the cap plate 228, may move horizontally to some extent to accommodate the swinging movement of the lever 208. To enable free horizontal movement the cylindrical projection of the block 226 is slidingly mounted within a passageway 236 in the machine frame 148.

Although the

feelers

46 and 154 are shown in the drawings as being arranged to engage the work operated upon directly in line with a seam inserted it may be advantageous under some conditions to arrange the feelers at a location out of line with the seam. Location of the feeler out of line with the seam may be desirable when the In chine is operated to sew outsoles or other heavy materials.

While the use of a feeler separate from a presser foot in a heavily constructed shoe outsole stitching machine is of benefit in adjusting both the clamping action of the presser foot and the pull-off action in a thread measuring mechanism, when the adjusting connections are of mechanical construction a separate feeler also is of marked advantage when a hydraulically operated presser foot is employed. In the latter instance the feeler is connected to a servo valve for adjusting the opera tion of the presser foot while the presser foot clamping and releasing movement may be accomplished by a simple piston and cylinder arrangement actuated by a cam on the main sewing shaft of the machine. Such hydraulic adjustment and actuation are of further benefit in avoiding lost motion normally occurring in mechanical mechanism and connections. A hydraulic system, thus, is enabled to reach higher speeds of machine operation without sacrificing accuracy of adjustment. In fact, in many instances a hydraulic adjusting system for the presser foot can be operated more uniformly and with less wear and abuse of the moving parts than is possible with a purely mechanical presser foot adjusting and actuating mechanism.

The present invention has been described as being applied to an outsole stitcher, but the features of invention relating to a feeler controlled presser foot may also be utilized effectively in a stitch separating machine of the type disclosed in United States Letters Patent No. 1,357,- 511, granted November 2, 1915 on application of Perry. Instead of stitch forming devices of an outsole stitcher, that machine is provided with operating devices including an indenting tool. In other respects a presser foot and a work support are utilized in that machine for purposes similar to those of the present sewing machine. Thus, the present invention is intended for use with machines for performing operations other than sewing, except for those features relating to thread measurement. With such use the terms operation performing and stitch forming are equivalents.

The nature and scope of the invention having been indicated and several embodiments having been described, what is claimed is:

1. A sewing machine having a frame, stitch forming devices in the frame, a main sewing shaft for actuating the stitch forming devices, a work support, a presser foot and mechanism for actuating the presser foot to clamp and release the work supported on the work support, including a presser foot lever, a presser foot cam on the sewing shaft, a follower engaging the presser foot cam, and a train of adjustable connections between the follower and the presser foot lever, in combination with a feeler arranged to engage the work between the work support and the presser foot for changing the adjustment of the connections between the follower and the presser foot levers as the thickness of the work varies between successive stitches.

2. A sewing machine, as in claim 1, in which there is provided resilient means connected with the feeler for pressing it against the work.

3. A sewing machine, as in claim 1, in which the adjustable connections include a first lever on which the cam follower is mounted, a plate having an arcuate slot, a second lever fulcrumed concentrically with the first lever, the plate being rotatably supported by one of the concentrically pivoted levers, a slider on the other concentrically pivoted lever, said slider engaging the slot in the plate and the feeler being connected to rotate the plate on the lever by which it is supported.

4. A sewing machine, as in claim 1, in which there is provided means for feeding the work comprising mechanism for moving the awl while engaging the work and a guide block for the feeler connected to the feeding mechanism to cause the feeler to partake of the work feeding movements.

5. A sewing machine, as in claim 1, in which there is provided means for feeding the work comprising a carrier for moving the work support and presser foot while clamping the work, and a guide mounted on the frame of the machine to prevent the feeler from moving with the work as the work is being fed.

6. A sewing machine, as in claim 1, in which there is provided resilient means connected with the presser foot acting to press the presser foot and the feeler against the work.

7. A sewing machine, as in claim 6, in which the presser foot mechanism actuates both the feeler toward and from the work to prevent the feeler from engaging the work frictionally.

8. A sewing machine, as in claim 3, in which the slotted plate is so supported on its pivoted lever that movement toward and from the work support is imparted to the feeler to prevent the feeler from engaging the work frictionally.

9. A sewing machine, as in claim 8, in which there are provided adjustable thread measuring mechanism and a lost motion joint between the feeler and the thread measuring mechanism to cause adjustment of the thread measuring mechanism when a change in the thickness of the work occurs and means for retaining the adjustment of the thread measuring mechanism during the relative movement of the parts in the lost motion joint.

10. A sewing machine having a frame, stitch forming devices in the frame, a main sewing shaft for actuating the stitch forming devices, a work support, a presser foot and mechanism for actuating the presser foot to clamp and release the work on the work support including a presser foot cam on the sewing shaft and a train of adjustable connections between the cam and the presser foot lever, in combination with a feeler arranged to engage the work between the work support and presser foot for changing the adjustment of the connections as the thickness of the work varies between successive stitches.

11. A sewing machine, as in claim 10, in which there is provided resilient means connected directly to the presser foot lever for pressing the feeler against the work through reaction on the adjustable connection.

References Cited by the Examiner UNITED STATES PATENTS 1,169,909 2/1916 Ashworth 112-38 2,271,611 2/1942 Ashworth et a1. 11238 2,750,908 6/1956 Odermann et a]. 112-235 FRANK I. COHEN, Primary Examiner.

P. D. LAWSON, Assistant Examiner.