US3473496A - Drive assembly to drive an automatic pattern-stitch sewing machine - Google Patents

Description

Oct. 21, 1969 T. HESZ 3,473,496

DRIVE ASSEMBLY TO DRIVE AN AUTOMATIC PATTERN-STITCH SEWING MACHINE Filed Dec. 29, 1966 4 Sheets-Sheet 1 I I l l Theodor Hesz Invenfor.

Attorney Get. 21, 1969 Filed Dec. 29, 1966 T. HESZ DRIVE ASSEMBLY TO DRIVE AN AUTOMATIC PATTERN-STITCH SEWING MACHINE 4 Sheets-Sheet 2 Fig.2

Theodor Hesz lnvenfor.

B m rl 6R0 Attorney Oct. 21, 1969 T. HEsz 3,473,496

DRIVE ASSEMBLY TO DRIVE AN AUTOMATIC PATTERN-STITCH SEWING MACHINE Filed Dec. 29, 1966 4 Sheets-Sheet 5 Fig.5c

Theodor Hesz Inventor.

6 53 By Y- Attorney T. HESZ 3,473,495 DRIVE ASSEMBLY TO DRIVE AN AUTOMATIC PATTERN-STITCH SEWING MACHINE Filed Dec. 29, 1966 4 shoetswShe-ot -t Theodor Hesz Invenfor.

5' 001 Attorney United States Patent M 3,473,496 DRIVE ASSEMBLY TO DRIVE AN AUTOMATIC PATTERN-STITCH SEWING MACHINE Theodor I-Iesz, Vienna, Austria, assignor to Arthur Schmid, Kreuzlingerstrasse, Grundweg, Romanshorn, Switzerland, a corporation of Switzerland Filed Dec. 29, 1966, Ser. No. 605,934 Claims priority, application Switzerland, Dec. 30, 1965, 18,177/65 Int. Cl. 1305b 11/00 F1611 3/08 US. Cl. 112-118 3 Claims ABSTRACT OF THE DISCLOSURE A pattern-stitch sewing machine for quilting and the like wherein the fabric is moved on a fabric guide rela tive to the needle bed by a pattern disk or cam, the guide carrying fabric-engaging rollers which are driven in step with the pattern guide. A shiftable guide transmission is interposed between the pattern-disk drive and the fabricadvance rollers and can be shifted between a normal gear ratio, a slightly larger gear ratio and a slightly smaller gear ratio for compensating for slip and stretch fabric. A periodically operable clutch can be interposed between the output of the transmission and the fabric-advance rollers when the fabric guide is to be shifted transversely to the direction of advance of the fabric.

The invention refers to a drive assembly for an automatic pattern-stitch sewing machine with continuous operation of the main drive shaft for the actual pattern device and its incorporated needles and shuttles and a stepped switching device integrally connected therewith for the staged drive of a pattern disc displacing the material guide back and forth and the movement of the material-feed rollers.

As is well known, in such automatic pattern-stitch or quilting sewing machines, the feed movement always takes place in rhythm (in cadence) with the sewing process in such way that it is carried out when the needles have been retracted from the material and the presser foot has released the material.

The movement of the material at right-angles to the axis or major dimension of the material web is controlled by the pattern disc, while feed in a longitudinal direction is carried out by the material-feed rollers. Where the automatic machine operates with several rows of needles, in the case of each pattern cycle (Le. a single complete revolution of the pattern disc) the feed-advance distance d must be in a definite relation to the fixed interval or spacing n of the needle rows, for example d=2n, as otherwise the pattern will be distorted. It may be remarked in passing that, when operating with one row of needles only, small variations in the feed-advance distance are less noticeable.

Even when the feed movement of the material-feed rollers is precisely correct, errors in the stitched pattern may still arise, for example because the material slips on the feed rollers or because it stretches. In fact the material to be pattern stitched usually consists of three layers, for example of one layer of cotton wool batting or wedding which is placed between two webs of cloth. Such materials vary considerably both with respect to the thickness of the intermediate layer and to the smoothness of the covering cloths. In order to allow for a given degree of slip or stretch it is possible to select the feed-advance distance or stroke, to which the pattern cycle is related, in an amount slightly larger than the theoretically accurate length and then to attempt by exerting more or less powerful braking effects on the storage roller to ar- 3,473,496 Patented Oct. 21, 1969 rive at the correct advance length or distance for stitching. But when working with a material that slips only slightly, the feed-advance distance or stroke is then too great.

The object of the present invention is to provide a drive assembly that permits the compensation of these errors and the setting of a feed-advance length or stroke suitable to the characteristics of the material.

The drive assembly according to the invention is characterised by the fact that it incorporates a switching mechanism by means of which the switched steps of the material feed rollers can be corrected. The drive can now either be designed to incorporate positive steps (with increased feed advance length) by comparison with the theoretically accurate feed advance length or negative steps by comparsion with a theoretically excessive feedadvance length. If the theoretically correct feed advance length is allotted the figure the following possibilities result:

It is possible to incorporate additional stages beyond the illustrative number of three.

It is an advantage if the drive assembly is provided with a device by means of which the feed advance can be cut out periodically in cadence with the cycle of the pattern disc. This enables, in particular, the stitching of checked patterns the seams of which run both parallel and at right-angles to the material web.

In the drawing an automatic pattern-stitch sewing machine with the new drive assembly is shown in simplified. In the drawing:

FIG. 1 shows an automatic pattern-stitch sewing machine With its drive assembly viewed from above;

FIG. 2 shows the drive in perspective;

FIG. 3 shows the switching gear thereof viewed from above;

FIGS. 4a-c and 5ac show various stitched patterns produced with two rows of needles;

FIG. 6 shows a checked pattern;

FIG. 7 shows a diagram of movements; and

FIG. 8 shows a pattern disk for the drive of the invention.

In FIG. 1 an automatic pattern-stitch sewing machine is shown in simplified form in which, for the sake of clarity, the actual stitching device with the rows of needles that move up and down etc. has been omitted. The automatic machine has a frame A on the right-hand side of which a drive housing B with the new drive assembly is mounted; the drive assembly is driven by the motor C. On the frame a material guide E slides within trestle arms D. The material-guide has mounted on it a material feed roller F and a roller G onto which the material web is rolled after having been pattern-stitched. It also bears the material-feed rollers H and the materialfeed-advance rollers J. On the frame is located a needle bed K with two rows or arrays of needles N and N the needle bed K also carries the main drive shaft L, which drives the actual stitching device (not shown).

The shaft L is driven by drive assembly B directly by way of a rigid (jaw) clutch Q. The number of revolutions per minute of this main drive shaft determines the speed with which the automatic machine operates. By using a V- belt drive with variable gear ratios, the operating speed of the automatic machine can be adjusted. (In the diagram a non-variable V-belt drive has been shown for the sake of simplicity.) On top of the drive housing B under a hinged cover R is located an easily interchangeable pattern disc U of a type well known. Its shape determines the pattern M stitched by the automatic machine. In fact it carries out a directing control on the back-and-forth movement of the material guide E, to which purpose the latter is displaced by one stitch interval at a time in the cadence of the pattern stitching by the drive assembly by way of a push rod V. By means of a handwheel Y, the feed-advance length per stitch or, alternatively, the total feed-advance length related to the pattern cycle can be corrected to conform to the material currently being processed. The switch lever Z permits the mechanism governing the periodical starting and stopping of the feed advance to be put into operation or cut out.

FIGURE 2 shows the drive assembly with the continuously driven main drive shaft L, the shaft X with stage by stage drive for the feed advance of the material guide and the push rod V which is moved back and forth step for step by the pattern disc U. The step by step movement it is provided by a stepped switching mechanism. This comprises a cam disc 1 rigid with the shaft L and moving a push rod 3 by means of a cam-follower roller 2.

By means of a pawl (not shown) and a U-shaped pivoting lever 4 the latter steps a toothed ratchet wheel 5 which turns forward the shaft 6 by one increment at a time. The roller 2 and the push rod 3 are held by means of the plate lever 7 so as to pivot and a spring 8 bearing on this plate presses the roller 2 onto the cam disc 1 and pulls the push rod 3 back after each travel stroke. By means of a set of conical toothed wheels (bevel gears) 10, 11, the shaft 6 drives the vertical shaft 12, at the upper end of which is fitted the pattern disc U which can be changed according to the pattern desired. Thus members 1 through 12 constitute a stepping mechanism operable by the main shaft L to incrementally advance the pattern disk U. This pattern disc drives a slide 14 by means of a roller 13 running on its circumference and this slide is connected with the push rod V.

The conical toothed wheel 11 also meshes with a toothed pinion 15 which by reason of the gear ratio selected for the shaft 16 drives it through twice the angular stepping of shaft 12. Torsionally rigid with the shaft 16 is a set of toothed wheels 17, 17', 17" which mesh with the toothed wheels 18, 19, 20. The center toothed wheel 19 is keyed to but axially displaceable on the grooved (splined) shaft 21 (see FIG. 3), while the wheels 18 and 20 are capable of turning freely on the shaft 21. The shaft 21 is fitted to a disengageable clutch 22 the secondary or output side of which drives the shaft X (FIG. 2).

The toothed wheel 19 can be displaced by means of the pivoted lever 23 which is forked at both ends. For this purpose, the pivoted lever can be pivoted about a fixed axle 24. Pivoting is carried out by means of a handwheel Y which protrudes from the front of the drive housing B. It is fitted with a disc 25 and a pin 26 mounted eccentrically thereon and received in the forward fork of the lever 23. If the centre toothed wheel 19 is moved to the left, first the mesh between the teeth of the wheels 1917' is disengaged and thereafter the switching teeth 19a mesh with the switching teeth 18a of the wheel 18 and a new ratio has been established (FIG. 3). There is a similar result when the toothed wheel 19 is displaced to the right. The number of teeth to the wheels is so selected that for example the following ratios can be selected:

Mesh 17-19 ratio=u=l03% d Mesh 17-18 ratio=u-34=l00% d Mesh 17"20 ratio=u+3%=l06% 0! Thus by comparison with the mean figure 103%, (l a somewhat larger and a somewhat smaller ratio are possible. Accordingly, the feed advance length for a particular fabric relative to the pattern cycle, can also be corrected or adjusted.

The clutch 22 is capable of being switched in and out periodically by means of the cam plate 30 which turns with the shaft 16. This is effected by means of a switching lever 31 and a roller 32 which can be brought within reach of the cam plate. In FIG. 2 this switching lever is shown out of action. It can be thrown out of action by means of the switching lever Z. For this purpose the disc 34 mounted eccentrically on the shaft 33, is turned and the lever 31 pressed downwardly. It then pivots about the bearing pin 35 of the plate 36 and the rear end of the lever with the roller lifts far enough for the roller 32 to come within reach of the cam plate 30. With every revolution of this cam plate, the lever will then be moved once laterally back and forth, pivoting about the pin 37 of the plate 36 and, by means of the switching fork 38 fixed to it, cutting the clutch 22 in and out. Finally, a spring 39 ensures that the roller 32 comes up against the cam disc 30 and that the lever 31 falls back into its original position.

By reference to FIGS. 4a-c and 5ac, the effect exerted by the corrections or adjustments on the feed-advance length d relative to the pattern cycle can be explained. In FIG. 4a the automatic machine is operating with two rows of needles Where however the needles are offset from one another. The interval or spacing (in the direction of material feed) between the rows of needles is n and the feed-advance length is d. In FIG. 4b the feed-advance length is exactly correct, namely d='2n and the peaks of the stitched zigzag seam touch one another so that a precise, diagonally arranged checked pattern is produced. The movement of the material takes place in the direction of the arrow d, the length of which corresponds to the feed-advance length (211). To stitch a pattern of this type a heart-shaped pattern disc, similar to that illustrated in FIGS. 1 and 2, is used. If the feed-advance length is greater or smaller than 2n, the peaks of the zigzag seam no longer touch one another, as FIGS. 4a and 40 show. It is also possible to work with two rows of needles and the needles arranged in line as shown in FIGS. 5ac. Using the same zigzag seam, a smaller checked pattern is then produced, the seams crossing one another. This obviates the sources of error where there are crossing points but the sources of error where the peaks should touch remain significant, as is shown by FIGS. 5a and 5c.

FIGURES 6 to 8 refer to the stitching of a rectangular checked pattern. This will be stitched with a single row of needles, as shown in FIG. 6, so that errors on the feed-advance length are less obvious. On the other hand, the difficulty now arises that the web of material has alternately to be advanced only or moved laterally only.

Control of such cross-movement can easily be achieved by means of a pattern disc in accordance with FIG. 8. If the rollers 13 (FIG. 2) run on that part of the pattern disc marked a a the material guide remains stationary. If on the contrary they run on the portion marked [3 -5 the material guide moves either to the right or to the left. This is shown schematically in FIG. 7. At the points marked with an a or an e the material-feed rollers must be cut out or in respectively. Thus in the course of a single revolution of the pattern disc the material-feed rollers must be cut in twice and out twice. This is effected by the switching cam 30 (FIG. 2) which periodically switches the clutch in and out. In fact the shaft 16 makes two revolutions during the period in which the vertical shaft 12, which bears the pattern disc, completes a single revolution. It is obvious that in place of the drive shown with only three stages one with more than three stages can be utilized. The switching can also be carried out in another manner, for example in the manner of a Norton transmission or by means of a draw wedge. The drive housing B is preferably filled with oil so that the drive is at all times lubricated. The pattern disc U is located above the cover of the housing beneath the hood R in air and is therefore easy to change. The shafts for the operating controls Y and Z (shaft 33) are ducted through the housing wall to the exterior through an oil-seal.

I claim:

1. In a pattern-stitch sewing machine having a needle bed, a fabric guide shiftable relative to said needle bed in a fabric-advance direction, fabric-engaging rollers on said guide and adapted to displace the fabric therealong, and a pattern disk for controlling the cyclical displacement of said guide, the improvement which comprises:

a drive assembly including a main drive shaft;

a stepping mechanism operable by said main drive shaft for incrementally displacing said pattern disk to shift said guide;

stepped transmission means between said mechanism and said rollers, said transmission means having a normal transmission ratio, a slightly higher transmission ratio and a slightly lower transmission ratio for rotating said rollers in step with the drive of said pattern disk;

means for selectively shifting said transmission means between said ratios to vary the rotational degree of said rollers with respect to the rotation of the pattern disk in accordance with the fabric stitched; and

periodically operable clutch means interposed between said transmission means and said rollers for periodically preventing rotation thereof by said transmission means in the cadence of operation of said pattern disk, said stepping mechanism comprising a pattern-disk drive shaft, a stepping shaft provided with a ratchet wheel, gear means connecting said stepping shaft with said pattern-disk drive shaft, a push rod reciprocable for stepping said ratchet wheel, and a cam carried by said main drive shaft and acting upon said push rod for reciprocating same;

said stepped transmission means including a further shaft provided with a gear meshing with said gear means, an output shaft operatively connected with said rollers, a first set of toothed wheels on said further shaft, and a second set of toothed wheels rotatably entraining said output shaft and mounted thereon with freedom of axial displacement of at least one of the toothed wheels of said second set whereby such axial displacement shifts said transmission means between said ratios; and

said means for shifting said transmission means including a shifting fork engaging the axially shiftable toothed wheel for selectively displacing same along said output shaft.

2. The improvement defined in claim 1 wherein said clutch means includes a clutch having an output side connected with said rollers and an input side connected with said output shaft, one of said sides being axially shiftable relative to the other of said sides to couple and decouple said clutch means selectively, and a cam carried by said further shaft for displacing the shiftable side of said clutch means.

3. The improvement defined in claim 2 wherein said clutch means further comprises a clutch lever engageable with the shiftable side of said clutch means and displaceable selectively between a position wherein said clutch lever engages said shiftable side and a position wherein said clutch lever clears said shiftable side, cam follower means on said clutch lever in the path of said cam, and manually operable means for selectively shifting said clutch lever between said positions.

References Cited UNITED STATES PATENTS 2,218,785 10/1940 Boettcher 112117 2,707,446 5/ 1955 McCutchen 112 118 X 3,051,012 8/1962 Sato 74333 X 3,238,904 3/1966 Hinko et al. 112118 3,249,077 5/1966 Schwarzberger 112-1 18 2,840,019 6/1958 Beasley 11279 2,855,879 10/1958 Minning et al. 11279 3,100,466 8/1963 Ledford et al. 112-79 MERVIN STEIN, Primary Examiner GEORGE V. LARKIN, Assistant Examiner US. Cl. X.R. 74333

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