VALSECCHI, Mauro (Via Unità d'Italia 31, Gambolo', I-27025, IT)
| CLAlMS
1. A clamp transport system for rocker arm stitching machine, with said rocker arm having, at top, a head (30) containing a crochet (31), rotating with respect to a horizontal axis, coinciding with a swinging axis of the arm (3), with the head (30) situated below the stitching needle (4), kept stationary with respect to the arm (3) swinging, by orientation means and supporting material to be stitched (M), with said clamp transport system (100) characterized in that it includes: said needle (4), going down to pass through said material to be stitched (M) and entering said head (30), as well as swinging on a vertical plane, in time relation with said lowered position, for a prefixed amplitude, corresponding to a stitch pitch of said material (M); a conveying foot (5), situated above said head (30) and being lowered, in time relation with the needle (4) going down, to contact the upper surface of said material to be stitched M, as well as swinging on a vertical plane, synchronously with said needle (4), in same direction and with equal amplitude; a lower gripping jaw (6), housed in said head (30); first operation means (61), situated inside said head (30) and connected kinematically with said crochet (31 ), said first operation means being designed to raise said lower gripping jaw (6) to protrude from said head (30) for contacting the lower surface of the material to be stitched (M,) in time relation with said conveying foot (5) going down; second operation means (62), situated inside said head (30) and rocker arm (3) and connected kinematically to said conveying foot (5), to make said lower gripping jaw (6) swing alternately, with same amplitude and in the same direction as the conveying foot (5), with said clamp transport system (100) clamping said material to be stitched (M) and conveying it for a feeding active stroke corresponding to one stitch pitch.
2. A clamp transport system for rocker arm stitching machine, with said rocker arm having, at top, a head (30) containing a crochet (31), rotating with respect to a horizontal axis, coinciding with a swinging axis of the arm (3), with the head (30) situated below the stitching needle (4), kept stationary with respect to the arm (3) swinging, by orientation means and supporting a material to be stitched (M), with said clamp transport system (100) characterized in that it includes: a conveying foot (5), situated above said head (30) and being lowered, to contact the upper surface of said material to be stitched M, in time relation with the needle taking (4) a raised position, not interfering with the material, as well as swinging on a vertical plane, for a prefixed amplitude corresponding to a stitch pitch of said material (M); a lower gripping jaw (6), housed in said head (30); first operation means (61), situated inside said head (30) and connected kinematically with said crochet (31), said first operation means being designed to raise said lower gripping jaw (6) to protrude from said head (30) for contacting the lower surface of the material to be stitched (M,) in time relation with said conveying foot (5) going down; second operation means (62), situated inside said head (30) and rocker arm (3) and connected kinematically to said conveying foot (5), to make said lower gripping jaw (6) swing alternately, with same amplitude and in the same direction as the conveying foot (5), with said clamp transport system (100) clamping said material to be stitched (M) and conveying it for a feeding active stroke corresponding to one stitch pitch.
3. A clamp transport system for rocker arm stitching machine, with said rocker arm having, at top, a head (30) containing a crochet (31), rotating with respect to a horizontal axis, coinciding with the swinging axis of the arm (3), with the head (30) situated below the stitching needle (4), kept statioanry with respect to the arm (3) swinging, by orientation means and supporting a material to be stitched (M), with said clamp transport system (100) characterized in that it includes: a conveying wheel, situated above said head (30), contacting the upper surface of said material to be stitched (M), and operated to rotate for a prefixed angular amplitude corresponding to one stitch pitch of said material (M), in time relation with the needle (4) raised position, not interfering with the material; a lower gripping jaw (6), housed in said head (30); flrst operation means (61), situated inside said head (30) and connected kinematically with said crochet (31 ), said first operation means being designed to raise said lower gripping jaw (6) to protrude from said head (30) for contacting the lower surface of the material to be stitched (M 1 ) in advance with respect to said conveying wheel rotation; second operation means (62), situated inside said head (30) and rocker arm (3) and connected kinematically to said conveying wheel, to make said lower gripping jaw (6) swing in accordance and synchronously with the conveying wheel rotation, with said clamp transport system clamping said material to be stitched (M) and conveying it for a feeding active stroke corresponding to one stitch pitch.
4. A clamp transport system, according to claim 1 , or 2 or 3, characterized in that said lower gripping jaw (6) has a hole (60), which allows said needle (4) to pass therethrough.
5. A clamp transport system, according to claim 1 , or 2 or 3, characterized in that said first operation means (61) include a cam (610), integral with a crochet operating member (32) driving said crochet (31) into rotation, with said cam (610) engaging with a slot (611), made in the body (6A) of said lower gripping jaw (6).
6. A clamp transport system, according to claim 1 , or 2 or 3, characterized in that said second operation means (62) include: a control lever (620), fastened in radial position to a secondary shaft (21) of said machine (1) and operated to swing alternately, with said control lever (620) connected, by interposition of a connecting rod (621), to a handle (622), carried by said rocker arm (3) and having the rotation axis coinciding with the axis of said rocker arm; a sector gear (623), integral with the handle (622) for operating a gear train (624) contained in the body of said rocker arm (3) and connected to a conical pinion (625), housed in said head (30); a jaw guide box (627), housed in said head (30), coaxial to said crochet (31) and having a conical crown wheel (626), which is in engagement with said conical pinion (625) and has a diametrically extending seat (628) engaging laterally the body (6A) of said lower gripping jaw (6), so as to transmit the alternate swinging motion to it, allowing the body (6A) to perform a vertical travel, imparted by said first operation means (61).
7. A clamp transport system, according to claim 1 , or 2 or 3, or 6, characterized in that said second operation means (62) compensate for the attitude of said jaw guide box (627) and lower gripping jaw (6), making them automatically counter- rotate by an equal angle and in the opposite direction with respect to the inclinations imposed to the rocker arm (3), which inclinations are compensated for, in relation to said head (30), by said orientation means. |
CLAMP TRANSPORT SYSTEM FOR ROCKER ARM STITCHING MACHINE
FIELD OF THE INVENTION
The invention relates to the technical field of two-thread lockstitch machines, aimed at stitching leathers, heavy fabrics, synthetic or semi-synthetic fibers (aramidic, etc.).
DESCRIPTION OF PRIOR ART
In one type of these machines, the needle is operated only in axial direction, with an up-and-down motion, which brings it alternately to go in and out of the material. The material is moved forward, between one stitch and the next one, by conveying means, e.g. feet, wheels or jaws, which act when the needle is outside of the material.
There is also another type of machines, in which the needle not only moves up and down, but also swings on its containing plane according to to and fro strokes, imposed in suitable time relation with the up and down motion; in these machines, the forward movement step occurs when the needle engages the material, in cooperation with the conveying means, associated to the needle.
The last mentioned machines, are called needle feed machines, or double feed, in which the material to be stitched is moved by the combined action of the needle and a transport foot, in combination with a leather holding down foot.
A machine of this type, produced by the Applicant, is particularly indicated for stitching shoe box soles and for stitching articles in leather and the like.
In this machine, like in other similar machines, the needle, as well as the transport and leather holding down feet are vertical and extend from the lower part of the machine head toward a rotating, or swinging hook device, situated below, commonly called "crochet", which in this case is introduced into a head associated to the top of a rocker arm, whose rotation axis coincides with the above mentioned crochet axis. The head, which carries the crochet, is kept in a stationary position, independently from the position assumed by the rocker arm, by interposition of orientation
means, provided for this purpose and aimed at making the head counter-rotate, with respect to the arm swinging, by the same angle.
The needle is operated to move up and down and, in suitable time relation, to swing on a vertical plane, parallel to the one of the crochet rotation, in order to move the material.
The transport foot is also operated to move up and down, by a relevant mechanism, and is fastened to the needle in such a way, as to follow its swinging; the leather holding down foot, situated downstream of the transport foot, is operated only vertically, with an up-and-down motion determined by the same mechanism of the transport foot, in combination with a pneumatic jack or a spring system.
The needle is lowered from a backward position with respect to the feeding direction of the material to be stitched, by passing through the latter and entering the crochet carrying head; likewise, the transport foot is lowered, in suitable time relation, to press the material against the plate formed by the head upper part.
In known way, the lowering of the transport foot determines, by means of the above mentioned mechanism, the raising of the leather holding down foot, which was kept elastically lowered by the jack to hold the material to be stitched during the needle backward stroke; then, the needle and the foot are operated to swing synchronously, to make the material move on the plate, until a prefixed stitch pitch is obtained.
During this step, the needle is situated inside the head and cooperates with the crochet to tie the two threads, one of which carried by the needle itself and the other coming from a bobbin contained in the crochet. The needle and the transport foot are then raised above the material to be stitched, in order to begin swinging in the opposite direction, which defines the return stroke; consequently, the jack is allowed to lower again the leather holding down foot, so as to hold the material in position.
Thus, the conformation of the mechanism operating the transport and leather holding down feet makes their movements interdependent, causing various disadvantages.
Actually, first of all, the transport foot has to press the material, tightening it on the
crochet plate, in order to obtain the derived movement, which allows to raise the leather holding down foot, overcoming the elastic thrust given by the jack; due to the transport foot pressure, the material slides on the crochet plate with difficulty, which makes the transport troublesome. Moreover, an excessive foot pressure can cause permanent marking of the leather or fabric, which is obviously unacceptable.
A further, but not less important disadvantage derives from the fact that the needle takes part in the transport of the material to be stitched, and therefore it is subjected to undesired bending stresses, which can cause its premature breaking and impose the use of suitably dimensioned diameters, which results in holes in the material bigger than necessary.
Due to the above mentioned difficulties in material sliding and/or needle bending, the double transport system can show irregularities in the stitch pitch and requires operator's help by accompanying the material feeding. The just mentioned disadvantages are further amplified if considerable variations of the material thickness occur during the stitching, caused by overlapped edges of flaps, tongues and the like.
The machines with horizontal working top, or with a stationary arm, use transport mechanisms, which engage the material from above (wheel or foot) and from below (lower gripping jaw) during the feeding, which can occur with the needle raised outside the material, if the needle moves only up and down, or with the needle engaged with the material, if it can swing.
This last case is defined as triple transport system (needle, transport foot and lower gripping jaw), which, as it is known to those skilled in the field, is the optimal solution for ensuring good material gripping, which is clamped between the foot and the jaw during the feeding step, so that the feeding is not contrasted by friction and is more regular, thus freeing the needle from those bending stresses which affect the double transport systems.
A triple transport system has not been used up till now in the rocker arm machines, because it is difficult to obtain a technical solution, which has at the same time precise movements and timing, which is strong, has reduced dimensions, and which is wholly compatible with the other mechanisms housed in
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the rocker arm, as well as with its movements.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to propose a clamp transport system for moving material to be stitched, to be associated to a rocker arm stitching machine, in which the needle moves up and down and swings.
Another object of the invention is to propose a clamp transport system for moving material to be stitched, to be associated to a rocker arm stitching machine, in which the needle moves only up and down. A further object of the invention is to propose a clamp transport system, in which the lower gripping element is housed in the crochet-carrying head and is operated by mechanical means, connected to the machine motor shaft, so as to ensure the correct timing with respect to the other machine means.
A still further object of the invention is to house the means for transmitting motion to the lower gripping element inside the crochet-carrying head and the rocker arm, maintaining the dimensions of the arm and in particular of the head, comparable with those of known type.
BRIEF DESCRIPTION OF FIGURES The characteristic features of the invention will become clear from the following description of preferred embodiments of the proposed transport system, in accordance with the contents of the claims and with help of the enclosed figures, in which:
- Figure 1 is a perspective view of the whole rocker arm stitching machine, having the proposed transport system;
- Figure 2 is a perspective view of the machine head, sectioned along a longitudinal vertical plane and with some parts removed in order to better point out others;
- Figure 3 is a perspective front view of the only rocker arm; - Figure 4 is a perspective rear view of the rocker arm, with some parts
sectioned;
- Figures 5A and 5B are exploded, respectively front and rear views of the inner means of the stitching head, situated on the top of the rocker arm;
- Figures 6A, 6B, 6C 1 6D are as many schematic, front views of the stitching means of the machine and of the clamp transport system, in subsequent working moments.
DESCRIPTION OF PREFERRED EMBODIMENTS
Having regards to the above mentioned Figures, reference numeral 1 indicates a two-thread lockstitch stitching machine, formed, in a way known in itself, by a head 2 and a rocker arm 3, situated below.
The rocker arm 3 has, at top, a head 30, aimed at receiving, on its upper part, the material M to be stitched, and containing a rotating hook device 31, the so-called crochet, situated below the stitching needle 4, extended from the lower part of the head 2.
The horizontal axis of the crochet 31 coincides with the arm 3 swinging axis; the head 30 is kept in a stationary position, independently from the position assumed by the rocker arm 3, by interposition of orientation means, aimed at determining, with respect to the arm 3 swinging, a counter-rotation of the head 30 by a same angle.
The above mentioned orientation means, of known type, are not shown in detail, as not relevant to the invention.
The machine 1 is for example needle feed machine, already mentioned in the introductory note, in which the needle 4 is operated to up and down motion, combined with an alternate swinging motion, extending in a vertical plane, parallel to the crochet 31 rotation one.
The needle 4 cooperates with conveying means, operated in time relation, to feed the material to be stitched M. In the shown example the conveying means are formed by a foot 5, operated to move up and down, in combination with a swinging motion, synchronized with the needle 4 motion and having the same direction and the same amplitude.
According to a known technique, the conveying foot 5 is shaped in such a way as to act in a region corresponding to the needle 4, and has suitable hole to allow the latter to pass therethrough; thus, the foot acts also as a guide for the needle, when it goes down and penetrates the material, preventing it from anomalous stresses.
The head 2 of the machine 1 contains a main shaft 20, driven into rotation, and a secondary shaft 21 , operated to swing by the main shaft 20 (Figure 2). The shafts are aimed at imparting, in known way, the respective motions to the needle 4 and foot 5, as well as the rotation to the crochet 31 ; the motion is transmitted to the latter by a gear train 33 contained in the body of the rocker arm 3 and engaging with a crochet operating member 32, housed in the head 30 and coaxial with the crochet 31 (Figures 4, 5A, 5B).
The clamp transport system 100, proposed by the present invention, according to the specific embodiment described above, includes the needle 4, the foot 5 and a lower gripping jaw 6, housed in the head 30.
According to a preferred embodiment, shown in the Figures, the lower gripping jaw 6 acts in a region corresponding to the needle 4, therefore its upper end has suitably a hole 60, which allows the needle 4 to pass therethrough.
The lower gripping jaw 6 is moved vertically, by first operation means 61 , connected kinematically with the crochet 31 via the crochet operating member 32, from a lowered position, inside the head 30, to a raised position, in which it protrudes above, from a window 3OA, made in the head 30.
According to the example, the first operation means 61 include a cam 610, integral with the crochet operating member 32, aimed at engaging a slot 611 , made in the body 6A of the lower gripping jaw 6 (Figures 5A, 5B).
The vertical travel of the jaw 6, caused by the first operation means 61 , does not change.
The lower gripping jaw 6 moves also between two extreme positions, from the right to the left, and vice-versa, due to the action of second operation means 62, connected kinematically to the conveying foot 5 and aimed at imparting, to the body 6A of the jaw 6, an alternate swinging motion on the same swinging plane of the conveying foot 5, of equal amplitude and the same direction with respect
thereto.
According to the example, the second operation means 62 include a control lever 620, fastened to the secondary shaft 21 in radial position, connected, by interposition of a connecting rod 621 , to a handle 622, carried by the rocker arm 3 and having the rotation axis coinciding with the axis of the latter (Figures 1 , 2).
A sector gear 623, integral with the handle 622, operates a corresponding gear train 624 contained in the body of the rocker arm 3 and in engagement with a conical pinion 625, housed in the head 30 (Figure 4).
The conical pinion 625 engages with a conical crown wheel 626, made in a ring- like jaw guide box 627, housed in the head 30 and coaxial with the crochet 31 (Figure 5A).
The box 627 has a seat 628, of diametrical extension, aimed at engaging laterally the body 6A of the gripping jaw 6, so as to transmit the alternate swinging motion to it, allowing the body 6A to perform a vertical travel, imparted by the first operation means 61 (Figures 5A, 5B).
The amplitude of the gripping jaw 6 swinging motion, defined by the second operation means 62, which take the motion from the secondary shaft 21, is automatically adjusted to the amplitude of the needle 4 and the conveying foot 5 by the devices for adjusting the stitch pitch, situated in the head 2 and not shown, as known.
It is important to point out that the above mentioned second operation means 62, as described, are aimed at transmitting the alternate swinging motion, acting at the same time as attitude compensators for the jaw guide box 627 and thus for the gripping jaw 6, making them automatically counter-rotate, correspondingly to the inclinations imposed to the rocker arm 3, similarly to the action of the orientation means for the head 30.
The clamp transport system 100 is aimed at clamping the material to be stitched M and at conveying it for an active feeding stroke, corresponding to one stitch pitch, as described later, in time relation with the action of a known leather holding down foot 7, mentioned in the introductory note, shown with broken line in Figures 6A and 6B.
In Figure 6A, the clamp transport system 100 is open, before the start of a new
stitching cycle:
- the needle 4 and the conveying foot 5 are raised from the material to be stitched M, after their synchronized counterclockwise swinging (arrow R1 ), which define the respective return stroke; - the lower gripping jaw 6 is lowered to the position inside the head 30, at the end of its rightward swinging (arrow R2), which defines its return stroke.
The leather holding down foot 7 is kept lowered, during the return strokes, to press the material to be stitched M against the head 30, in order to keep it in position. In Figure 6B the clamp transport system 100 is closed to clamp the material to be stitched M:
- the needle 4 is lowered to pass through the material M and enter the head 30;
- the conveying foot 5 is lowered to contact the material to be stitched M from above; - the lower gripping jaw 6 is raised to protrude from the head 30 and contact the material to be stitched M from below.
The leather holding down foot 7 is raised from the material to be stitched M in time relation.
In Figure 6C, the clamp transport system 100, kept closed to clamp the material to be stitched M, has performed an active stroke for material feeding, corresponding to one stitch pitch:
- the needle 4, lowered inside the head 30, has completed the swinging in clockwise direction (arrow A1 ), cooperating in the same time with the crochet 31 , not shown, in forming a stitch; - the conveying foot 5, lowered to touch the material M, has completed its swinging in clockwise direction (arrow A1 ), synchronized with the needle 4 swinging;
- the lower gripping jaw 6, raised to touch the material M, has completed its leftward swinging (arrow A2), synchronized with the swinging of the needle 4 and of the foot 5.
The leather holding down foot 7, not shown, is kept raised from the material to be stitched M.
In Figure 6D, the clamp transport system 100 is open at the end of the stitch formation, before the beginning of the return stroke: - the needle 4 and the conveying foot 5 are raised from the material to be stitched M, after their synchronized clockwise swinging;
- the lower gripping jaw 6 is lowered inside the head 30 at the end of its leftward swinging, synchronized with the swinging of the needle 4 and of the foot 5.
The leather holding down foot 7, not shown, is lowered to press the material to be stitched M against the head 30, in order to keep it in position.
As it results obvious from the above description, the material to be stitched M, clamped between the conveying foot 5 and the lower gripping jaw 6, is fed without dragging on the head 30 and without bending stresses to the needle 4, which accompanies the movement without taking part in it. This allows to increase the needle 4 life and to reduce its diameter, which results in smaller holes in the material and improvement of the textile tightness to water infiltration.
The above described clamp transport system 100 allows to stitch without problems two overlapped layers of material, without their previous gluing to avoid undesired relative sliding, which can occur in known machines, during transport step, due to the different friction, which acts negatively also on the needle.
Another advantage of the clamp transport system 100 lies in a much more precise and constant stitch length, reducing at the same time the dependence on the operator's ability. The mechanical motion transmission allows to have a secure timing of the lower gripping jaw with respect to the needle and the conveying foot, which ensures a reliable working.
Moreover, the just described technical solution is optimal to contain the dimensions of the head and rocker arm, in spite of the presence of numerous additional means with respect to prior art.
The above described clamp transport system can be used, with similar
advantages, also in rocker arm stitching machines, in which the needle moves only up and down.
In these machines, not shown, the material to be stitched is fed, as it has already been said, when the needle is above it, therefore in this case, the clamp transport system does not include the needle; consequently, its operation timing is suitably modified with respect to the latter.
A first embodiment of the clamp transport system suitable for these machines, not shown, includes a swinging transport foot and a lower gripping jaw similar to the ones described above. According to a second embodiment, still referred to the above machines, the system includes, besides the lower gripping jaw, a transport wheel, instead of the foot.
The transport wheel, situated above the head 30 (not shown), contacts the upper surface of the material to be stitched M and is aimed at being driven to rotate for a prefixed angular amplitude, in time relation with the needle raised position, as already said, and with the lower gripping jaw swinging during said feeding stroke.
In the last case, the machine may lack the leather holding down foot.
The proposed clamp transport system can be advantageously used in rocker arm machines aimed at different processing than stitching, such as e.g. glue application.
Moreover, the clamp transport system is also suitable for machines with rocker arm of different conformation with respect to the one shown in the enclosed figures, such as machines with rotating arm, that is capable of performing 360° and wider travels, in one direction or the other, and also for stationary arm machines.
Consequently, the proposed clamp transport system allows a considerable improvement of the machines, to which it is applied, without jeopardizing their reliability and/or versatility, due to mechanically sophisticated technical solutions.
It is understood that what has been said above is a mere, not limiting example. Therefore, any possible changes or variants applied to the described means, considered necessary due to technical-functional needs, remain within the protective scope defined by the following claims.