US2178531A - Sewing machine - Google Patents

Description

ct. 31, 1939.. N. F. HOPKINS I 291735531 SEWING MACHINE Filed Jan. 7, 1937 3 Sheets-Sheet. l,

38 1 e O o 20 0 lllmn HT mum @at 33, 3339, N. F. HOPKINS w filfl SEWING MACHINE Filed Jan. 7, 1937 3 Sheets-Sheet 2 N HGPKXNS SEWI m moan;

Filed Jan. '7, 1937 5 Sheets-Sheet 5 Patented Get. 31, 1939 SEWING MACHHNE Nathan Freeman Hopkins, Rockland, Mass, as-

signcr to United Shoe Machinery Corporation, Borough of Flemington, N. .15., a corporation of New Jersey Application January 7, 1937, Serial No. 119,445

4 Claims.

The present invention relates to wax thread shoe sewing machines, and is intended primarily as an improvement in a lockstitc'n outsole shoe stitcher or" the type described in the U. S. Patent application of Haas, Serial No. 76,924, filed April 29, 1936, in which a measured amount of locking thread is drawn from the supply for use in each stitch by changing the position relatively to the work of the thread case in which the supply is contained.

In the machine of the Haas application referred to, after the measured amount of locking thread rendered available for use in a stitch, the length of locking thread between the thread 5 case and the work becomes loose so that the needle loop, as it is drawn from the thread case, frequently engages the locking thread in an irregular manner, causing successive stitches to be formed imperfectly and with the lock between the two threads at dilierent locations in the work. In the Wing machine disclosed in U. S.

patent application of Haas Serial No. 118,622

filed December 31, 1936, this difficulty is avoided by holding irictionally the measured amount of 5 locking thread against movement towards the work after being rendered available for use. The locking thread is measured in the latter machine by deflecting the thread between a pair of locking thread grippers, one of which acts to hold the amount measured against movement towards the work until drawn towards the work by the needle loop. In the machine of application Serial No. 76,924 the locking thread is drawn oir from the supply in the thread case of the machine by rotating the thread case so that the opening through which the thread passes towards the work is moved away from the work. With this arrangement, it is impractical to apply a frictional tension device to the thread case for holding the measured amount of thread against movement towards the work and to provide such a device elsewhere would crowd the space surrounding the point of operation of the stitch forming devices so as to interfere with the proper operation of the other devices.

The object of the present invention is to simplify the construction and improve the mode of operation of a wax thread lockstitch shoe sewing machine having means for measuring locking thread for each stitch, and particularly to pro-- vide a sewing machine or" the type disclosed in application Serial No. 76,924, in which the locking thread, after the measured amount is ren dered available for use in a stitch, will be held rigid between the supply and the work without (Cl. Ill-58) undesirably affecting the operation of the machine in other respects.

With these and other objects in view, a feature of the present invention contemplates the provision in a hook needle lockstitch sewing machine having a loop taker, a thread case, a takeup and means for drawing off and rendering available for each stitch, a measured amount of thread from a supply in the thread case, of yielding means for taking up the measured amount of thread when said amount is rendered available, so that the length of locking thread between the thread case and the work is held rigid without the use of a frictional tension device for that purpose. In the form of the invention illustrated, the yielding means comprises a thread engaging arm of relatively light construction on the thread case arranged yieldingly to take the locking thread so as to follow accurately the neasuring movements of the thread case to take out the looseness in the locking thread between the thread case and the work at all times.

Other features of the invention, including certain novel and improved constructions and arrangements of parts, are herein described in the following detained specification and more particularly pointed out in the appended claims.

In the drawings Fig. l is a view in front elevaiton of a portion of the machine embodying the features of the present invention; Fig. 2 is a plan view of the supporting and actuating portions of the shuttle and thread case of the machine; Fig. 3 is a sectional view, taken along the line S-3 of Fig. 2; Fig. 4 is a detail plan view of the thread case; 5 is a developed view of a side portion of the thread case, indicating the relations of the parts for guiding and taking up the measured locking thread; Figs. 6 to 9 inclusive, are detail views illustrating successive relative positions of certain of the stitch forming devices during the operation of the machine; Figs. ill and ll sectional views on an enlarged scale of a portion of work illustrating the formation of the seam being sewed in the machine and Fig. 12 is a detail view of a threadgripping member employed on the thread case.

Except as her fter described, the machine illustrated in the drawings is the same in construction, arrangement and mode of operation of its various parts the machines disclosed in the Haas application Serial No. 76,924, hereinbefore referred to, and in the U. S. patent to Haas No. 2,045,644, of June 30, 1936. As in the machines of the patent application referred vature or the side wall of amount or" to, the sewing devices comprise a curved hook needle 2, a curved awl 4, a rotary shuttle or loop taker 6 for passing a loop of needle thread about a thread case 8, shown in Figs. 3 and 4, a main take-up [0, an auxiliary take-up l2, a work support I4, and a presser-foot [6. The thread case is rotatably mounted within the shuttle, and is held from rotation with the shuttle by two reciprocating pins l8 and 2D alternately engaging notches 22 at the upper edge of the thread case. The take-up acts to draw each needle loop from the thread case and to pull the interlocked threads into the work before each stitch is set. Within the thread case is mounted a bobbin 24 on which the loo-king thread 26 is wound, and the locking thread is led through an opening 28 (see Fig. in the side of the thread case, beneath a leaf spring tension device 30 and along one side of the thread case towards the work. As it passes along the side of the thread case, it it engaged by a pair of grippers comprising, as in the machine of application Serial No. 76,924, a movable gripping member 32 (Fig. 12) and a cooperating fixed block 34 on the thread case for gripping the looking thread as each stitch is being set so that thread will not be drawn off from the thread case by the needle loop. The movable gripping member 32 is curved to correspond with the curthe thread case and is pivoted on a stud 36 mounted in the thread case. It is held in engagement with the thread by means of a compression spring 31.

In the machine of Serial No. 76,924, a measured locking thread is drawn off from the thread case to provide sufficient thread for a stitch and during measurement the thread is released from the grip of the gripping member corresponding to member 32 in the present machine. To measure the thread, the thread case is rotated slightly, first in one direction, causing the thread to be drawn through the opening 28 in the thread case, and then in the reverse direction to render the measured amount available for use in a stitch. To rotate the thread case, the reciprocating pins [8 and 20 are mounted, as in the machine of Serial No. 76,924, in a carrier 38 rotatable in a support 40 secured to a circular guideway 42 for the shuttle. The carrier 38 is rotated in its support and the gripping member 32 is actuated to release the thread by mechanism including a link 4| connected to the carrier and other connections more fully described in said application.

In the machine of the application Serial No. 118,622 the locking thread is drawn off from the thread case for each stitch by deflecting a portion or the thread as it passes along the side of the thread case. While the locking thread is being deflected, it is engaged between the point of deflection and the work by a gripper which holds it against movement away from the work so as to prevent displacement of the previously formed stitch in the work. The thread is thus necessarily drawn from the supply in the thread case and when rendered available for use, the gripper member acts as a frictional tension device to hold taut the length of looking thread extending from the thread case to the work. As each needle loop is drawn from the thread case by the take-up, it engages the rigid length of locking thread between the thread case and the work, which guides the movements or the needle loop until the needle loop is drawn tight about the locking thread. In this way the needle loop is prevented from gripping the locking thread against the surface of the work before coming into definite engagement with the locking thread at a fixed distance from the previous stitch.

In certain cases, due to slippage through the locking thread gripper of the machine of application Serial No. 118,622 or to other causes, the length of locking thread between the thread case and the work may become loosened slightly so that the guiding action of the needle loop by the locking thread as it is drawn from the thread case is rendered less effective. To prevent any looseness in the length of locking thread between the thread case and the work, in the machine embodying the present invention, there is mounted on the thread case a thread guiding arm 44 arranged to be actuated yieldingly to take up automatically any looseness in said length of thread. The yielding action of the arm 44 is insufiicient to affect the formation and setting of a stitch, but is sufficient to prevent the needle loop as it is drawn towards the work, from being tightened initially against the locking thread at a point where it is supported by the work, so that the point of engagement between the threads after the locking thread is brought against the work is accurately fixed with relation to the last stitch in the work.

As illustrated in Fig. 10, the positions of the threads are indicated at a point just before a stitch is pulled into the work. At this point the locking thread is shown as being gripped by the needle loop against the upper surface of the work so that considerable resistance is offered to the necessary relative sliding movement between the needle loop and locking thread after this point is reached while the stitch is being pulled in and set in the position illustrated in Fig. 11. If the looseness had not been taken out of the locking thread before the position of Fig. is reached, there would be a tendency to grip the locking thread by the needle loop at an irregular distance from the previous stitch thus requiring an irregular sliding movement of the locking thread through the tightened needle loop before the stitch was set. The action of the yielding arm 44 prevents the slightest looseness of the locking thread before the position of Fig. 10 is reached so that difiiculty from the cause referred to is eliminated.

The thread engaging arm 44 is mounted to swing on a pin 46 at the lower end of the looking member 32 on the thread case. To guide the thread, the arm 44 is formed with oppositely disposed slots 48 and 50 (see Fig. 5) extending lengthwise of the arm in positions to receive the locking thread as it leaves the grip of the member 32. For actuating the arm 44 yieldingly to take up the thread, the lower end of the gripper member 32 is recessed to receive a compression spring 52, one end of which engages the end of a recess and the other end of which engages a lug portion 54 of the arm 44.

The operation of the yielding arm 44 will be apparent from an inspection of Figs 6 to 9 inclusive, which illustrate the different positions of the arm as a stitch is being formed and set. At the time each needle loop is being drawn from the thread case towards the work, it takes an indefinite course, being guided only by the length of locking thread between the thread case and the work. During its continued movement, the needle loop is rapidly closed upon the locking thread and the locking thread, as indicated in Fig. 6, being held taut by the arm 34i, causes the needle loop to be drawn tight. Before the position of the threads shown in Fig. 10 is reached, the threads are free to slide along each other until the needle loop is tightened on the locking thread at a definite distance from the previous stitch. The stitch thus formed is pulled into the work and set, causing the thread engaging arm d to be swung about the pin d5 into a more nearly vertical position, as illustrated '7. Thereafter, the member 32 releases the locking thread and the thread case is rotated in a counter-clockwise direction to draw oiT a measured amount of thread for the succeeding stitch, as shown in Fig. 8. After the new supply of thread has been measured, the member 32 again grips the thread, as illustrated in Fig 9, the measuring arm l l still being in the position of Fig. '7. As the measured amount of locking thread is rendered available for use in a stitch by rotating the thread case in a clockwise direction, the arm dd immediately swings upwardly, taking up the measured amount of thread to maintain rigidity in the length extending from the thread case to the Work, as shown in Fig. 6.

ihe nature and scope of the invention having been indicated and the specific embodiment oi the features of the invention having been desoribed, what is claimed is:

1. A lockstitch sewing machine having, in combination, a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case towards the work, means for drawing from the supply a measured amount of locking thread and for rendering the measured amount available for use in a stitch, and yielding means for taking up the measured amount of locking thread as the measured amount is rendered available.

2. A lockstitch sewing machine having, in combination, a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case towards the work, means for drawing from the supply a measured amount of locking thread and for rendering the measured amount available for use in a stitch, and a yielding arm on the thread case for taking up the measured amount of locking thread as the measured amount is rendered available.

3. A lockstitch sewing machine having, in combination, a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case towards the work, mechanism for rotating the thread case in one direction during each stitching cycle to draw off from the supply a measured amount of locking thread and for rotating the thread case in the reverse direction to render the measured amount available for use in a stitch, and a yielding arm on the thread case for taking up the measured amount of locking thread after the thread case is rotated in a direction to render the measured amount available.

4. A lockstitch sewing machine having, in combination, a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case towards the work, means for rotating the thread case to draw from the supply a measured amount of locking thread and to render the measured amount available for use in a stitch, a thread gripping member on the thread case arranged to release the locking thread while the thread case is being rotated to draw off thread, and a yielding arm on the thread gripping member for taking up the measured amount of locking thread as the thread case is rotated in a direction to render the measured amount available.

NATHAN FREEMAN HOPKINS.

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