Sewing machine

Abstract

 The zigzag-sewing and feeding system of a sewing machine comprises two step motors (1, 2), one (1) of which is used to effect and control the zig-zag sewing motion of a needle bar holder. The other step motor (2) is used to control the stroke of the back-and-forth movement of the feeder (21) of the sewing machine.
The drive shaft (3) of the first step motor (1) carries a gear in mesh with a rack (4), which is pivoted at one end to one end of a bell-crank lever (5), which at its other end is pivoted to one end of a cranked lever (6) and is operated by the rack (4) to reciprocate said one end of the cranked lever (6). The latter is pivoted at a bend to the machine frame and is pivoted at its other end to a needle bar holder (8) to impart a zigzag motion thereto. The rack (4) is formed with longitudinal slots, which receive pins (11) for guiding the rack (4) during its reciprocating motion.
The drive shaft (12) of the second step motor (2) carries a gear in mesh with a rack (13), which is pivoted to one end of a bell-crank lever (14), which at its other end is pivoted to a connecting rod (15) by a pivot (14') between the upper end lower ends of said rod. A tension spring (16) is connected to the connecting rod (15) above the pivot (14') and urges said rod (15) above the pivot (14') against the eccentric periphery of a cam (17), which is rotated by the main motor (19) of the sewing machine. The lower end of the connecting rod (15) is connected by a transversely extending rod (20) to the feeder of the sewing machine so that said feeder is moved back and forth by said rod (20) when the rotation of the cam (17) causes the lower end of the connecting rod (15) to oscillate about the pivot (14'). The amplitude of said oscillation will be controlled by the step motor (2), which is operable to shift by means of the rack (13) and the bell-crank lever (14) the point of contact between the connecting rod (15) and the cam (17). The rack (13) is also formed with longitudinal slots, which receive pins for guiding the rack (13) during its reciprocating motion.

Description

INVENTION'S DATA

[0001] The purpose of the present Letters Patent application relates to certain developments brought in a zigzag and transporting motion for sewing machines which provides essential characteristics in newness as compared with similar systems known and used to the same purpose. More specially this invention is aimed to the featuring of a zigzag motion operated by means of two single engines of the kind known as stepper motors and accurately synchronized each other in order to obtain the desired results.

[0002] Capabilities of accuracy and control offered by stepper motors have determined the fast spreading of them and their application to the most diverse engineering fields. In the concrete field of the sewing machines there are now at the market some models which featu­re this kind of engine for the performing of some specific operation.

A SHORT DESCRIPTION OF DEVICE

[0003] Developments which are the object of the present invention have foreseen the use of two stepper motors by means of which and through adequate media it is provided in an independent manner the zigzag movement of needle and advance of propelling gear. Therefor, driving shaft of a first stepper motor gears up a rack which by an end couples itself with the end of a lever cranked at some points and pivotable in relation of one of said elbowing points, which at its opposite end also fastens itself in an articulated manner to the supporting part of the needle's bar. The above supporting piece fits by its upper end with pivoting capability in relation with its fas­tening point.

[0004] Second stepper motor gears up its driving axle with a rack which induces a change in the operation, as from its mean point, of a connecting rod which by its upper side keeps a permanen contact to an eccentric thanks to action of a tension spring, such an accentric being driven by the operation of the main motor of the machine while by its lowest end accounts on a driving shaft for the forward and back motion of the carrying means of the machine, setting out such an axle by virtue of the oscillating motion of connecting rod, an arch which larger or smaller amplitude depends on the said raid po­sitioning and which in turn translates itself into a larger or smaller displacement of said conveyor means.

[0005] Controlled actuation of both stepper motors named above shall be performed through electronic media and preferably by means of a microprocessor.

A BRIEF DESCRIPTION OF DEVICE

[0006] Detailed description of the invention subject which follows shall refer notwithstanding to the enclosed drawings where by way of example and without limiting character therefore a preferred form of realization is displayed. By these drawings:

Figure 1 shows an elevational view in section, of a sewing machi­ne which features the developments which are the subject of the in­vention.

Figure 2 shows a ground-plant view of the sewing machine shown by the Figure 1.

Figure 3 illustrates a face elevation view of a cross section made at the sewing machine of Figure 1 in the proximity of the position of the stepper motor which drives the conveyor mechanism of the ma­chine.

[0007] Referring firstly to Figure 1, it can be seen thereat an elevatio­nal view of a longitudinal section made by a sewing machine which features the developments which are the subject of this invention. By this Figure it can be seen a first stepper motor marked with nu­merical reference 1 and a second stepper motor marked with numerical reference 2. Driving shaft 3 of motor 1 operates a reack piece 4 hinged at an end with a middle piece 5, which owns its opposite end likewise hinged with a lever 6 cranked by different points along its length. Said lever 6 fastens itself pivotably to machine chassis by one of its points 7 of elbowing and it has its free end clamped also pivotably, preferably by means of a screw 9 to a piece 8 of suppor­ting of the bar 10 of the needle. Rack piece 4 is driven by its re­ciprocating travel by means of stubs 11 bored in openings made thereat.

[0008] Second motor 2 has its driving shaft 12 connected to a rack piece 13 through a middle piece 14 allowing this way shifting of posi­tioning of connecting rod 15. Upper end of said connecting rod 15 finds itself urged by the traction of a spring 16, then said connec­ting rod leans itself permanently against an eccentric 17 linked with a shaft 18 which gets motion from the main motor 19 of the machine by means of a belt or another type of transmission.

[0009] Connecting rod 15 is interlocked by its lowest end to an horizon­tal axle 20 by virtue of which oscillating movement of said connec­ting rod transforms itself into a travel forward and back motion of the carrying device of the machine. Obviously this oscillating move­ment of connecting rod 15 takes place around shaft 14' of the middle piece 14.

[0010] Shaft 22, driven by the main motor 19 of machine prefarably by means of a belt must provide to carrying device 21 in a known manner the lifting and lowering motion.

[0011] At Figura 2 is represented a view of ground-plant of machine as per Figura 1 where different components are shown of which constitu­tes the subject of invention and relative position kept thereamong. Thus it can be seen the connecting rood 15 which rests by its upper side on eccentric 17 fastened to shaft 18, being able such axle 18 to operate, in a known manner, different organs of the machine; posi­tion of stepper motors 1 and 2 and their associated elements and upper clamping of support piece 8 for the needle bar 10 assured by a short axle 23 in relation of which it can pivot.

[0012] By Figura 3 it can be seen a cross section drawn by the machine in the proximity of the position of the second stepper motor 2. By said Figure may be perfectly seen, position, shape and operation of the different elements associated to said motor 2. This way it can be seen the rack piece 13 geared up the driving axle of the motor 2 and shiftable by it, fastened by the lowest side to the end of a middle piece 14 which opposite end hinges to connecting rod 15. Like­wise it may be seen the spring 16 which exerts traction on the upper end of said connecting rod 15 to keep it permanently resting on the peripheric surface of eccentric 17. On the lower side said connecting rod 15 is connected to carrying device by means of shaft 20.

[0013] Driving of both motors 1 and 2 shall be independent as above quo­ted, and shall be controlled by electronic means. These electronic means can be known or not, and able to be programmed for the opera­tion in the time of both motors 1 and 2 according to results which attainment should be desirable.

[0014] According to above, motor 1 shall be used to provide a zigzag motion to machine needle. Therefor said stepper motor duly controlled by the electronic means shall provide to rack 4 a reciprocating move­ment to be transmitted through the middle piece 5 to the end related to cranked lever 6, which opposite end is hinged joint through screw 9 to support 8 of the needle bar. This way reciprocating motion of rack 4 becomes the zigzag movement desired for the needle.

[0015] This embodiment has the advantage that by means of a minor number of simple elements is possible to come to end the zigzag effect of the needle. It is understandable that a larger or smaller amplitude of the reciprocating motion of rack 4 translates itself respectively in a larger or smaller width of zigzag; then if duly regulated every moment the travel of rack 4 it can be obtained a predetermined shape of zigzag.

[0016] Stepper motor 2 is in charge of regulating the shifting limits of travelling device of the machine. In fact the above travelling devi­ce is subject to the combination of two movements, i.e., one of lifting-lowering and other of forward-back motion. Lifting-lowering movement is provided in a known manner as above quoted by shaft 22 driven by the main motor of the machine. Forward-back motion is operated by shaft 20 when actuating on such travelling device 21 when driven in turn by the connecting rod 15.

[0017] The movement of the shaft 20 is bent-shpaed, of larger or smaller amplitude according to the position adopted by the rack 13. According to Figures 1 and 3, after connecting machine to network, starts motion of shaft 18 which hauls eccentric 17 communicating a recipro­cicating motion to the upper end of the connecting rod 15 and taking place pivoting of that in relation of axle 14' by means of which is connected to middle piece 14. Lowest end of connecting rod draws an arch centered at shaft 14' of pivoting and which amplitude depends on distance between pivoting shaft 14' and the contact point between connecting rod 15 and eccentric 17. For the position shown at Figure 3, arch run by the lowest end of the connecting rod 15 (and also by axle 20) shall have a defined amplitude which translates itself in a concrete shifting of the carrying device. Notwithstanding, actua­ting on motor 2 shall change the position of rack 13 and consequently connecting rod shall be shifted altering the distance existing between shaft 14' of pivoting and the contact point of connecting rod 15 and eccentric 17 resulting in a variation of the amplitud of the arch drawn by the lowest end of connecting rod 15 and by axle 20 resulting in a larger or smaller travelling of carrying device, as the case may be.

[0018] Advantage of this embodiment is that only is necessary to use a reduced number of simple components in order to provide to the carrying device for a forward-back travelling. It must be understood that when operating properly on the said stepper motor 2 either by programming or by any other means it is possible to regulate on time the shifting of carrying device, if desired.

[0019] Effect of combined regulation of both stepper motors 1 and 2 by means of programming or by any other proper means allows obtaining on fabrics any kind of figure or drawing desired.

[0020] Invention have been described according to a preferred embodiment of same. It must be realized notwithstanding that within its essen­tiality might be introduced multiple variations of detail likewise protected which could effect its shape, size or manufacturing mate­rials of assembly or its parts without altering at all the object of the invention.

Claims

1.- Developments brought in a zigzag and transport device for sewing machines characterized by the foreseeing of the embodying of two stepper motors, one of them aimed to performing of zigzag and width regulation of same, and the other assigned to move and regula­te shifting of carrying device of the machine, in order to which, the said first stepper motor gears up its driving shaft in a first rack, trained by means of stubs housed in openings made thereat, which through a middle piece induces reciprocating movement to the end of a crankinglever which has its opposite end pivotably connec­ted to the resting piece of the needle bar, while the second stepper motor has its driving shaft geared up likewise with a second rack connected to an end of its middle piece and to which opposite end pivotably clamps itself a connecting rod which has its upper end urged to traction by a spring for permanently resting on an accentric interlocked to an axle driven by the main motor of the machine while the lowest end of said connecting rod is provided with an axle which when operating on the carrying device of machine causes its shifting.

2.- Developments according to claim 1 characterized because the variation of limits of reciprocating motion of the said first rack induces the variation of the zigzag width attained by the needle of the machine.

3.- Developments according to claims 1 and 2 characterized because the variation of positioning of the said second rack shall induce likewise variation in the height of said connecting rod being conse­quently modified likewise the width of arch run by the lowest end of connecting rod and associated shaft and moreover the limits of shifting of the machine carrying device.

Drawing