Device for orienting the needles of an automatic sewing machine

Abstract

 The present invention relates to a device for orienting the needles of an automatic sewing machine, comprising means (1) adapted to operate in the end portion of the raising stroke of the needle bearing bar (2) to rotate through a half of turn, in a direction,and then relocate,in the other direc­tion,a movable assembly including a rod (3),a clamp bearing block (4),clamp members (5) and the needles (6).

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a device for orienting the needles in an automatic sewing machine.

[0002] As is known in the automatic sewing machine field there are included those sewing machines provided with a pair of needles which are arranged in an adjoining relationship and at the same level, and which jointly move so as to form,supplied from the same "crochet",seaming stitches.

[0003] Also known is the fact that,by reversing the positions of the needles,it is possible to form particular types of stitches,such as,for example decorative or pattern stitches.

[0004] A drawback of these machines is that the orien­tation of the needles does not remain unchanged in the assumed positions,as it would be necessary.

[0005] Another drawback is the difficult of controlling the exchange of the needles,for example in a modern computer controlled sewing machine.

SUMMARY OF THE INVENTION

[0006] Accordingly,the task of the present invention is to overcome the above mentioned drawbacks,by providing a device which can be easily associated with or controlled by a computerized unit so as to afford the possibility,with a given needle exchange operations,of providing a high number of different stitches,in succession.

[0007] Within the scope of the above task,a main object of the present invention is to provide such a device which can be easily and quickly appli­ed to existing sewing machines without the need of replacing the vertical operating rod of the sewing machine or changing its vertical movement and which moreover comprises movable parts of very reduced weight so as to provide a high speed operation of the sewing machine.

[0008] According to one aspect of the present invention,the above mentioned task and objects,as well as yet other objects,which will become more apparent hereinafter,are achieved by a device for orienting the needles in an automatic sewing machine, characterized in that it comprises means operating during the end portion of the raising stroke of the needle bearing bar so as to rotate through a half turn,in a direction,and then re-locate,in the opposite direction,the movable assembly comprising therein a rod member , the clamp bearing bloc,the clamps and the needles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Further characteristics and advantages of the device according to the present invention,will become more apparent hereinafter,from the following detailed description of a preferred embodiment thereof,which is illustrated,by way of an indicative but not limitative example,in the figures of the accompanying drawings,where

Figure 1 is a cross-sectional front view of the needle orienting device according to the present invention;

figure 2 is a top plan view,partially cross-sectioned,of the needle orienting device ac­cording to the invention;

figure 3 is a schematic view illustrating the clamps of the sewing machine which are rotated in a direction;
and

figure 4 is a schematic view illustrating the relocating step of the clamps.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0010] With reference to the figures of the accompany­ing drawings,the device for orienting the needles of a sewing machine according to the present invention comprises means 1 adapted to operate during the end portion of the raising stroke of the needle bearing bar 2 to rotate for a half turn,in a direction, and relocate,in the opposite direction,the sewing machine movable assembly consisting of the rod 3, the clamp bearing or holding block4,the clamps 5 and the needles 6.

[0011] The reciprocating movement of the needle bar 2 is obtained by means of known systems,for example a linkage system,and causes the needles 6 to operate so as to form the stitches.

[0012] The mentioned means 1 essentially consist of an axial cam shaped tubular element 7 which, on its outer surface,bears two front helicoidal profiles 8,which start from a top point 33,one in the left direction and the other in the right direction,and two longitudinal slots 9 having a greater length than the vertical stroke of the bar 2 and arranged with a diametrically opposite relationship.

[0013] The bar 2 supports,in its inside,the rotat­ing rod 3 which projects at both ends and the bottom portion of which supports the clamp bearing block 4,whilst its top portion supports the tubular element 7 which,as aforesaid,forms the rotating "cam".

[0014] The disclosed mechanism can be easily coupled to a very reliable computerized unit able of driving only the engaging operation or clutch operation, whereas the rotation through 180°,for exchanging the needles 6,is carried out by exploiting the last portion of the raising stroke (as the needles are disengaged from the material to be stitched) of the bar 2 which,as aforesaid,is driven with a reciprocat­ing vertical movement driven by known means.

[0015] Since the rotation mechanism is of a positive type,the rotation path,as it is started,will be surely completed.

[0016] The mentioned slots 9 are communicated by another double helicoidal profile 10.

[0017] As,during the rotation of the cam 7,one of the profiles 8 starts to slide on a portion of a clutch outer assembly 11,a pin 52,engaging with one of the slots 9,will start to slide on one of the profiles 10 so as to engage with the other diametrically opposite slot.

[0018] The outer clutch assembly comprises two clutch members 13 which are mutually coupled and adapted to alternatively engage either one or the other of the helicoidal front profiles of the cam 7,transverse­ly of its axis.

[0019] The rod 3 is provided,at the top,with a tapered portion 12 which,during the raising stroke of said rod 3,before the engaging of one of the two clutch members 13 with one of the other front profiles 8,will be located so as to prevent a not controlled displacement of the outer assembly 11 from occur­ring.

[0020] The helicoidal profile 10,which has preferably the same pitch as the profiles 8,starts so as to be rightward directed at one side and leftward directed at the other side,starting from a point 34.

[0021] Said profile 8 ends with an enlarged portion which acts as a discharging portion,at one of the mentioned slots 9.

[0022] The outer clutch assembly 11 is moreover provided,at a middle position,with an element 14 adapted to prevent not controlled engagements of said assembly 11 from occurring;more specifically the element 14 is so shaped as to prevent the assembly 11 from disavantageously impacting against the tapered portion 12 at the top of the rod 3,in the case of an erroneous driving.

[0023] The cam 7 is provided with further safety means, consisting of a movable locating element 15,which preferably consists of a ball,provided with a spring return element 16.Said element 15 is adapted,by a transversal movement,to alternatively engage in one of the two longitudinal slots 9,so as to hold a constant orientation of the cam 7,even in the case of possible rotations caused on said rod 3 by stresses occurring on the needles 6 during the seaming operation.

[0024] The clamp bearing block 4,which is rigid with the rotating rod 3 is provided,at the bottom thereof,with two blind longitudinal holes 17 which have axes equally spaced from the axis of the rod 3. Said blind holes 17 house two needle bearing clamps 5 which are able of freely rotating about their axes, which is parallel to or slightly slanted with respect to the axis of the rod 3.

[0025] The clamps 5 are surely affixed, against possible displacements, by pins 18 or other restraining elements which have preferably a semicircular cross-­section,said pins 18 being adapted to engage in the side wall of a slot formed in the stem 19 of each said needle bearing clamps 5.

[0026] Preferably the stem 19 has a cylindrical shape and is so shaped as to abut,by a projecting portion 20,against rotation limit elements,which are also able of orienting said clamps 5.

[0027] The elements 21 comprise the walls of a radially extending slot 23,defined on a tubular gui­de 24,which is arranged outside and coaxially of the clamp bearing block 4 and being rigid with the bar 2.

[0028] The mentioned elements 21 comprise moreover two pins 25 which are force engaged in longitudinal recesses formed in the clamp bearing block 4,so as to project from the lower surface of said block 4; as shown the pins 25 are arranged at diametrically opposite positions on a connecting line which is perpendicular to the axes of the holes 17 anchoring the clamps 5.

[0029] These needle bearing clamps 5 bear,each, at their bottom portion,a hole 26,therein a needle 6 is mounted the axis of which is spaced,with respect to the axis 19 of the clamp 5,respectively,one toward the projecting portion 20 and the other in the opposite direction.The needles 6,in particular,are preferably slightly slanted and converge toward the tips so as to define with the axis of the rod 3,there­with they are not coplanar,a small angle adapted to facilitate the stitch forming operation.

[0030] With this inclination of the needles 6, said needles are prevented from bending during the penetration into the fabric material to be stitched, in particular as this material is folded in order to form,for example,a rib shape.

[0031] At the reference number 27 there is indicated the frame of the sewing machine to the bottom portion of which there is locked the tubular element 28 which operates as a guide for the displacement of the tubular element 29,which is in turn locked at the top portion of the frame 27.

[0032] The element 29 also acts as a support for the tubular casing 30 which is included in the disclos­ed rotation mechanism,which also comprises the mention­ed cam 7.

[0033] The two clutch elements 13 are mutually coupled by the slide 31 which bears at the top,at its center, the point 14 facing the cam 7 and able,as it is operat­ed by any suitable mechanical or electromagnetic suitable means,or by a pneumatic cylinder the rod of which is indicated at 32,of carrying out the displace­ment shown in figure 1.

[0034] From the above disclosure,it should be apparent that the invention fully achieves the intended task and objects.

[0035] In particular it should be pointed out that the tapered portion 12 does not cross the transversal path of the element 14 during the displa­cement of the slide 31.

[0036] This occurs as the bar 2 is arranged at the middle and bottom portion of its stroke,whereas, during the raising stroke,the tapered portion 12 will cross the transversal trajectory of the element 14,before the engaging of one of the two clutch elements with the front helicoidal profile 8,thereby generating the rotating movement.

[0037] Thus the clutch element 13,engaging with one of the front helicoidal profiles of the cam 7, will be safely prevented from disengaging from said profile,for example because a malfunction of the system driving the slide 31,before the overtaking by the guide element 52 of the critical point 34 of the double helicoidal slot 10,along the side,which could cause the breakage of operating elements.

[0038] Another important aspect of the present invention is that the locating element 15 (ball), urged by the spring 16,prevents possible rotary displacements from occurring at the top of the cam 7 stroke caused by stresses acting on the needles 6 or on the clamps 5.

[0039] With respect to the orientation of the clamps 5 and,accordingly,of the needles 6,with refe­rence to figures 3 and 4,it should be apparent that, by rotating the block 4 anticlockwise, the clamp 5′ will be arranged at the position of figure 3,whilst the other clamp 5˝ will be arranged at the opposite position,and said clamps will be prevented from rotating by the pins 25′ and 25˝ and by the walls 22 of the guide element 24 which is rigid with the bar 2 and,because of this fact,it can not rotate.

[0040] By rotating clockwise the block 4,it should be apparent that,during the first portion of this rotation,the clamps 5,disengaged from the walls 22 of the slot 23 formed on the element 24 (which does not rotate) are free of moving so as to be oriented again, during the last portion of the rotation stroke,by the wall 22 of the slots 23 and by the pins 25.

[0041] At the end of the 180° clockwise rotation, therefore,the clamp 5′ will be arranged at the position of figure 4 while the clamp 5˝ will be arranged at the opposite position.

[0042] It should moreover be pointed out that,owing to the offset of the needles 6 from the axis of the bar 2,the yarn will be engaged in an easier way during the operation of the sewing machine,thereby providing an improved cooperation of the needles 6 and crochet.

[0043] While the invention has been disclosed and illustrated with reference to a preferred embodiment thereof,it should be apparent that the disclosed embodiment is susceptible to many modifications and variations all of which will come within the spirit and scope of the appended claims.

[0044] In particular,in practicing the invention, the used material,provided that they are compatible with the intended use,as well as the contingent shapes and size can be any according to requirements.

Claims

1- A device for orienting the needles of an automatic sewing machine,characterized in that it comprises means (1) adapted to operate during the end portion of the raising stroke of the needle bearing bar (2) to rotate through a half turn,in a direction,and then relocate,in the other direction,a movable assembly consisting of a rod (3),a clamp bearing block (4),clamps (5) and needles (6)

2- A device for orienting needles according to the preceding claims,characterized in that said means (1) consist of a tubular element (7) having on its outer surface two front helicoidal profiles (8), respectively extending one in a rightward direction and the other in a leftward direction,and two diametrically opposite longitudinal slots (9) which have a lenght greater than the vertical stroke of said bar (2).

3- A device for orienting needles,according to one of the preceding claims,characterized in that said longitudinal slots (19) are coupled by other two helicoidal side profiles (10),respectively directed in a rightward direction and in a leftward direction, so that as said cam is rotated one of said front profiles (8) slides on a portion of an outer clutch assembly (11) and simultaneously a pin (52) engaging with one of said longitudinal slots (9) starts to slide on one of said side profiles (10) so as to engage with the other diametrically opposite longitu­dinal slot.

4- A device for orienting needles, according to one or more of the preceding claims,characterized in that said rod (3) which is rotatably supported by said bar (2) and projects from both ends of said cam (7), is provided,at the top thereof,with a tapering portion(12) which,during the raising stroke of said rod (3),before one of two clutch members (13) engages one of said front helicoidal profiles (8) of said cam (7),is so arranged as to prevent said outer clutch assembly (11) from being displaced in a not controlled way.

5- A device for orienting needles,according to one or more of the preceding claims,characterized in that said outer clutch assembly (11) comprises two mutually coupled clutch members adapted to alternatively engage either one or the other said front helicoidal profile of said cam (7) transversely of its axis.

6- A device for orienting needles,according to one or more of the preceding claims,characterized in that said outer clutch assembly is provided,at a middle portion thereof,with an element (14) for preventing said clutch assembly from disengaging in a not controll­ed way said element having a pointed shape.

7- A device for orienting needles,according to one or more of the preceding claims,characterized in that said cam (7) is provided with safety means consisting of a movable locating element (15) including spring return means (16),adapted to be transversely displac­ed for alternatively engaging in one of said longitu­dinal slots (9) so as to hold said cam (7) in a set position.

8- A device for orienting needles,according to one or more of the preceding claims,characterized in that said clamp bearing block (4),rigid with said rotating rod (3),is provided,at its bottom,with two longitudinal blind holes (17) having axes equally spaced from the axis of said rotating rod (3) and slightly converging toward the tip portions of said needles (6).

9- A device for orienting needles according to one or more of the preceding claims,characterized in that said longitudinal blind holes (17) houses two needle bearing clamps (5) which are able of freely rotating and are restrained by a pin (18),having a semicircular cross-section,adapted to engage in the side wall of a slot,formed on the stem (19) of each said needle bearing clamps (5).

10- A device for orienting needles according to one or more of the preceding claims characterized in that said needle bearing clamps (5) are provided with a cylindrical stem (19) having a shaped body adapted to abut,by a projecting portion (20) against rotation limit elements (21).

11- A device for orienting needles according to one or more of the preceding claims,characterized in that said clamps are each provided,at the bottom thereof, with a hole (26) therein a respective needle (6) is engaged,the axis of said holes being spaced,with respect to the axis of said stem (19) of said clamp respectively one in the direction of said projecting portion (20) and the other in the opposite direction.

12- A device for orienting needles according to one or more of the preceding claims, characterized in that said needles (6) are slightly slanted and converge toward the tip portions thereof so as to define,with the axis of said rod (3),therewith they are not coplanar, a small angle.

13- A device according to one or more of the preceding claims,characterized in that said rotation limit elements comprise the walls (22) of a radially extend­ing slot (23) formed on an outer tubular element (24) which is coaxial to said clamp bearing block (4) and rigid with said bar (2).

14- A device according to one or more of the preceding claims,characterized in that said elements (21) comprise two pins (25) force fitted into longitudinal recesses of said block so as to project from its bottom at diametrically opposite positions and on a coupling line perpendicular to the axes of said holes (17) for anchoring said clamps (5).

Drawing