Machine for lifting and cutting warp oriented sewing threads

Abstract

 A machine (1) for cutting warp oriented sew threads on an embroidered fabric or on a fabric with sewn features, comprises means driving and tensioning the running fabric web (2) to slide onto a transversal channel-shaped support (3), a thread lifting and cutting wedges carrying transversal arm (4) reciprocatingly moved at a high frequency, the arm (4) having a plurality of thread lifting wedges (6) a certain number of which oriented in a direction and the others in the opposite direction along the reciprocating arm (4), the point of each wedge (6) pressing with a certain angle of incidence on the surface of the running fabric (2) in correspondence of the channel-shaped support (3) and each wedge (6) having a blade (9) that cuts the threads engaged and lifted over the upper edge thereof.
According to this invention, the machine (1) outstandingly reduces lateral thrusts impressed to the web (2) using a rotating circular blade (9) pivoted on the body of each wedge (6), each wedge (6) having at least a pulley (18) on the axle of the respective circular blade (9) engaged by a transmission belt or chain (19) and the reciprocating transversal arm (4) carries at least a motor drive assembly (10) transmitting the motion at least to a pulley (17) of a circular blade (9) of a first intermediate wedge of the plurality of wedges (6).

Description

[0001] The present invention generally relates to machines for producing fabric webs and in particular to machines for cutting sew threads.

[0002] In producing embroidered fabric webs or with similar features implying the realization of embroidery designs, buttonholes and/or sewings spaced along the fabric, there is the need of finishing operations including the cutting of sew threads between consecutively produced features on the fabric web such to interrupt continuity of the thread between the end of a sewing and the beginning of the successive sewing, and the subsequent rising and cropping of the lifted pieces of thread.

[0003] In the case of weft oriented sew threads, they can be cut easily by thread lifting wedges operatively oriented in opposition to the running direction of the fabric such to engage each thread, lift it over the upper edge of the respective wedge up to a blade position that cuts the thread.

[0004] By contrast, in the case of warp oriented sew threads, it is necessary to employ a dedicated machine for cutting the sew threads, a transversal arm carrying thread lifting and cutting wedges of which is moved in an alternative or reciprocating fashion at a relatively high frequency over the running fabric web.

[0005] Also in this case, the thread lifting and cutting implements are wedge-shaped and provided with a blade over which the engaged thread eventually slide.

[0006] In order to avoid inducing a lateral reciprocating thrust on the running fabric, a number (half) of transversally acting thread lifting wedges are oriented toward one side and the rest (the other half) of thread lifting and cutting wedges toward the opposite side such to "balance" the lateral thrust impressed to the running web.

[0007] Notwithstanding this expedient, these known cutting devices wherein the upper inclined edge of each thread lifting wedge is provided with a sharpened blade portion over which the engaged thread eventually comes to slide ramping up from the tip of the wedge, induce nonnegligible lateral thrusts and stresses on the running fabric web even if oriented in opposite direction of engagement with the threads, and this may cause problems.

[0008] Moreover, the blade edge must be regularly sharpened to ensure an effective cutting action on the threads. A progressive blunting of the edge increases the lateral thrust that is impressed to the fabric web.

[0009] It has been found and is the object of the present invention an improved machine for cutting warp oriented sew threads that allows a sensible and stable reduction of the lateral thrusts impressed to the web and to ensure an effective cutting action of the sew threads for long periods, limiting the frequency of substitution of the lifting and cutting wedges mounted along the transversal arm of the device that is reciprocatingly moved at high frequency.

[0010] The machine for cutting warp oriented sew threads of the invention is characterized by the fact that on each transversally acting wedge is pivoted a circular blade that is rotated by a belt transmission driven by a motor installed on the transversal arm carrying the wedges.

[0011] The essential features of the machine of the invention are defined in claim 1, and particularly effective embodiments are defined in the dependent claims.

[0012] The different aspects and advantages of the invention will be even more evident through the following description of an embodiment and by referring to the attached drawings, wherein:

Figure 1 is a lateral view of a machine of the present invention for cutting warp oriented sew threads;

Figure 2 is a detailed view of the sew threads cutting devices of the machine of the present invention;

Figure 3 is a front view of the transversal wedges supporting arm of the machine of the present invention.

[0013] A schematic lateral view of a machine of the invention 1 for cutting sew threads is depicted in Fig. 1. In this schematic lateral view, the organs that ordinarily drive the fabric web 2 to pass over a transversal channel-shaped support 3 of the machine with an appropriate tension. In the upper portion of the machine there are organs for supporting a wedges carrying transversal arm 4 in a position such that thread lifting wedges are pressed on the face of the running fabric web in correspondence of the channel of the transversal support 3 and for moving the arm transversally to the direction of the running fabric web in a high frequency reciprocating fashion.

[0014] A front view of the reciprocating wedges carrying arm 4 of the machine of the invention is depicted in Fig. 3, while details of the rotating blade thread cutting devices, according to a preferred embodiment, are highlighted in Fig. 2.

[0015] Customarily, as can be observed in Fig. 3, the arm 4 has a plurality of thread lifting wedges 6. A half of wedges are oriented in a transversal direction and the other half in the opposite transversal direction, such that with the high frequency alternated motion of the arm 4, impressed through the crank 7 driven by a motor group 8, the fabric web running under the transversal arm 4 is subjected to lateral thrusts alternately in one and in the opposite direction because of the engagement of warp oriented sew threads by a first half of wedges and successively by the other half of wedges of the array thereof carried by the transversally reciprocating arm.

[0016] A fundamental characteristic of the machine of the invention is that the cutting of the threads lifted by the wedges is produced by a circular blade 9 mounted on each thread lifting wedge 6 that is rotated through a belt or chain transmission. The driving motor 10 is mounted directly on the transversal arm 4. Of course, more than one motor and relative transmission may be used, respectively for portions of the total number of wedges.

[0017] As observable in the detail view of Fig. 2, the transversal arm 4 is slidingly supported by a beam 11 of the machine, on ball-bearings or equivalent low friction devices 12a and 12b.

[0018] The motor drive assembly that rotates the blades 10 is mounted on the reciprocating arm 4. Through speed reducing gears 13 and 14 an appropriate torque is transmitted by a chain 15 running on toothed wheels 16 and 17 to the rotating blade 9 of a first thread lifting wedge 6; usually, one of the two central wedges of the array of wedges 6 mounted along the lower edge of the reciprocating transversal arm 4.

[0019] On the same rotating axis of the wheel 17 of the rotating blade 9 of the wedge 6, is mounted at least a pulley or gear 18 through which rotation impressed to the blade of the first wedge is transmitted to all the other pulleys or gears 18 of the rotating blade 9 of all other wedges 6 of the array.

[0020] To transmit rotation to the circular blades pivoted on the respective thread lifting wedges, thin belts or chains 19 can be used, similar to the chain 15 that transmits the motion from the monitorized drive 10 to the axis of the rotating blade at least of a first wedge.

[0021] Of course, the transmission of motion progressively from the circular blade of one or two first intermediate wedges to that all the other wedges mounted along the two branches of the arm 4 can be organized in different ways, by using a single recirculating belt, running on pulleys and/or rotating pivots present on each wedge, or more belts may be used, providing the wedges with double pulleys and/or with rotating pivots or redirecting pulleys, according to common transmission techniques.

[0022] The rotating blades 9 may be realized such to "interfere" with the surface of the body of the thread lifting wedge to provide for a self sharpening action.

[0023] In any case, the cutting action of the rotating blades far more effective than that of the fixed blades of the known machines, retains its effectiveness for far longer periods than the fixed blades present on the upper edge of thread lifting wedges of known machines, thus avoiding the need of frequent substitutions of blades (or of wedges).

[0024] The body of each thread lifting wedge 6 can be customarily fixed to the arm 4 with screws, bolts or equivalent fastenings, one of which passing through a graduated adjustment slot to allow adjustment of the angle of incidence of the wedge out the surface of the running fabric web.

[0025] Normally, in order to effectively engage and lift sew threads between end points and start points of successive sewings relatively close to each other (up to 0,5 cm distance of separation between one thread and another) it is necessary to orient the wedges with a relatively accentuated angle of incidence while in case of threads more spaced from one another the angle of incidence may be reduced.

[0026] It is also possible to pivot the wedges on the arm 4 and engage a second pin in an appendix of the arm 4 that can be shifted in an adjustable manner, in order to adjust the angle of incidence of all (or of a first half and separately of the other half) the wedges of the array with a single adjustment operation by modifying the relative position of the appendix in respect to the arm 4.

Claims

1. A machine for cutting warp oriented sew threads on an embroidered fabric or on a fabric with sewing features, comprising means driving and tensioning a running fabric web to slide onto a transversal channel-shaped support a thread lifting and cutting wedges carrying transversal arm reciprocatingly moved at a high frequency, said arm having a plurality of thread lifting wedges a certain number of which oriented in a direction and the others in the opposite direction along the longitudinal axis of said reciprocating arm, the point of each wedge pressing with a certain angle of incidence on the surface of the running fabric in correspondence of said channel-shaped support and each wedge having a blade cutting the threads engaged and lifted along the upper edge thereof, characterized in that

said blade is a rotating circular blade pivoted on the body of each wedge;

each wedge having at least a pulley on the axle of the respective circular blade engaged by a transmission belt or chain;

said arm carrying at least a motor drive assembly transmitting the motion at least to a pulley of a circular blade of a first intermediate wedge of said plurality of wedges.

2. The machine for cutting warp oriented sew threads of claim 1, characterized in that said circular rotating blade is disk-shaped.

3. The machine for cutting warp oriented sew threads of claim 1, wherein several transmission belts or chains transmit the rotating motion to pulleys of respective circular blades of the wedges uniformly distributed along an edge of said reciprocating transversal arm.

4. The machine for cutting warp oriented sew threads, of claim 1, wherein the angle of incidence of each wedge onto the running fabric web is adjustable.

Drawing