INDUSTRIAL SEWING MACHINE

Abstract: An industrial sewing machine for the completion of a button hole (1) comprises a needle holder (20) that is connected via an arm (21) to means which ensure a forward and backward motion perpendicular to the direction of the needle. The aforementioned means bring an extremity (22) of the arm turned away from the needle holder into a forward and backward motion perpendicular to the direction (23) of the arm. The arm carries a cam (24) which slides in a fitting manner in a groove (25) of a first body (26) that in itself slides in a groove (32) of a further body (33) which is connected to a fixed portion (100) of the device. Because the first and further groove (25, 32) extend under a non-perpendicular angle to the direction of the arm, the arm is forced to move to and fro. The amplitude of the motion is proportional to the cosine of the angle of the groove and eventually determines the stitch bite of the needle, which width is thereby easily adjustable by means of the pivotably suspended first body (26). The cutting space may be adjusted by sliding the first body (25) within the groove of the further body (33).

Description: Industrial sewing machine. The present invention pertains to an industrial sewing machine for the completion of a button hole in a fabric, which button hole may or may not have been already opened, comprising a needle holder for the purposes of receiving a needle therein, which needle holder is coupled via an arm to means which, at least during operation, force the needle holder to move to and fro substantially transverse to the direction of the needle. Such a sewing machine sees greatest application in sewing workshops and in a factory environment whereby clothing is manufactured on a large scale. The current device is employed thereby specifically for the making of button holes such as the keyhole type depicted in figure 1. The entire button hole is thereby finished with an all-around zigzag stitch. This serves not only to improve appearances, but it also prevents possible fraying of the fabric which was cut in the vicinity of the hole. The fabric can be pre-cut at the location of the button hole which is being introduced, in which case one speaks of a 'cut-before' button hole, or otherwise can be incised after the stitching has been performed, which results in a so-called 'cut after' button hole. Both cases are depicted in figures 2B and 2A, respectively. A characteristic difference between both types is the small intermediate opening between both stitched sides - the so-called 'cutting space' - which must be taken into account to allow room for the knife with which the button hole will be subsequently realised. Such an intermediate opening is generally not present in the case of a 'cut before' button hole. If desired, a supplementary strengthening thread can be employed along the edge of the button hole. Depending on the type of fabric in use or based on the demands and wishes of a fashion designer or buyer, it will be necessary to adjust the sewing machine to suit the generation of either 'cut before' or 'cut after' button holes. With the first type of button hole, whereby the fabric is first cut and then the button hole is stitched, the inner edge of the button hole is nicely finished with the stitch-pattern. For these purposes, a fairly high degree of precision is required, which, in turn, requires that any play in the machine should be kept to a minimum. Because of the resulting higher costs of manufacture, such button holes are normally only used in more luxurious garments such as, for example, overcoats, sports coats, robes and pants. The 'cut after' button holes, which remain characterised by a narrow, more or less frayed edge in the fabric cut within the button hole, and a slightly narrower stitch bite, are mainly used in casual clothing such as jeans and jackets and for less expensive clothing. In the case of a known device of the type referred to in the opening paragraph, a highly- trained technician is required to switch the machine between production of each type of button hole. The person who normally operates the machine is generally incapable of performing this task. Also, even for the aforementioned technician, the adjustment of the stitch bite and any switching of the button hole mode, i.e. 'cut before' vs 'cut after', requiring an accurate adjustment of the required stitch bite and 'cutting space' takes some 15-30 minutes, during which time the machine will be out of service. It is an aim of the current invention to provide a device of the type referred to in the introduction, whereby, in a quick and simple manner, the stitch bite and cutting space can be adjusted. It is furthermore a goal of the invention to provide for a simple switching between both types of button holes in such a manner that the person operating the machine could this himself without external help. In order to meet the desired target, an industrial sewing machine of the type referred to in the opening paragraph is characterised in that said means comprise oscillation means which, at least during operation, cause an extremity of the arm turned away from the needle holder to move to and fro substantially transverse to the direction of the arm, in that the arm carries a cam which is received in a groove of a pivotably suspended first body, which groove extends under a non-perpendicular angle to the axial direction of the arm, and in that said first body is adjustably fixed in a groove of a further body that is connected to a fixed portion of the device, which groove of said further body also extends under a non-perpendicular angle to the axial direction of the arm. The cam shall exhibit a forward and backward motion in the groove of the first body as a result of the oscillating motion of the extremity of the arm. Because the angle between the groove and the direction of the arm deviates from a right angle, a forward and backward motion of the arm results, which motion is proportional to the cosine of the aforementioned angle. This motion is responsible for the stitch bite of the thread because the needle holder containing the needle is forced to follow this movement. The stitch bite can be easily set by varying the angle of the pivotably suspended first body, and thereby of the groove in it, with respect to the direction arm. By sliding the first body in the groove of said further body and thereby giving a greater or lesser offset to the arm, the intermediate cutting space between both stitch strips can be adjusted as desired. In a further particular embodiment, the device according to the invention is thereby characterised in that the hinging ability of the body is deliberately limited between previously-determined first and second extremity positions. In particular thereby, if, in further accordance with a preferential embodiment of the device according to the invention, the body is adjusted in the groove of the further body in such a manner that the machine produces a rather wide stitch bite in a first extremity position of the body with no room or very little room within the button hole, and it, in the second extremity position, produces a narrower stitch bite in combination with a certain separation within the button hole, then the machine can be switched between both modes of button hole production in an extremely easy fashion in a manner which requires the use of no additional tools and no special technical knowledge. The person who normally operates the machine can then perform this operation himself without any doubt. The invention will now be further elucidated on the basis of an exemplary embodiment and an accompanying drawing. In this drawing: Fig. 1 depicts an example of a button hole of the so-called key-hole type which can be produced with the sewing machine according to the invention; Fig's. 2A-2B show button holes of the 'cut after' and 'cut before' types, respectively; Fig. 3 shows a cut-away view of an embodiment of means in an exemplary embodiment of the sewing machine ac cording to the invention, which means provide for a forward and backward motion of the sewing needle; Fig. 4 depicts the components of figure 3 in an assembled state; Fig. 5 provides a detail view of a portion of an exemplary embodiment of the sewing machine according to the invention; and Fig. 6 shows a cut-away detail view of the device in figure 5 viewed from the opposite direction. The drawing is purely schematic in nature and is not drawn to scale. In particular, for purposes of clarity, some dimensions have been strongly exaggerated in the drawings. Where possible, one and the same parts are referred to with consistent numbering across the drawings. Figure 1 depicts an example of a button hole 1 of the so-called keyhole variety which can be produced with a sewing machine according to the invention. The button hole comprises peripheral stitching 2 which is used to border the enclosed opening. The button hole exhibits a circular widening 3 at one of its extremities, within which widening a decoration such as a flower, for example, can be inserted, and which widening gives this button hole its characteristic shape. The button hole can be manufactured in two global ways depicted in figures 2 A and 2B, respectively. In a first one - the so-called 'cut after' type - both rows 21, 22 with stitching keep a certain mutual separation distance CS within which the button hole is cut after the stitching is completed. Moreover, this type of button hole has a slightly narrower stitch bite SB than the second type that is indicated in figure 2B and is usually referred to as a 'cut before' button hole. In the latter case, the fabric is first cut and only then is the button hole sewn. A much prettier result is achieved in this manner because any possible fraying of the edge of the button hole is covered with stitching; if desired, through the use of a strengthening thread. A 'cut before' button hole demands a higher degree of precision from the machine, whereby this latter type of button hole will be generally more expensive and is usually reserved for more luxurious garments. The characteristic zig-zag stitch used to finish the button hole is achieved by an oscillating movement of the needle holder which carries the sewing needle, at least during operation. The needle holder is received by the fork projection from a rotating element 20, see figures 3 and 4, but for sake of clarity left out from the drawings. An oscillating rotation over a small angle of said element 20 forces the needle holder back and forth in a direction transverse to the sewing direction in order to obtain the characteristic zig-zag stitch. The element is coupled 20 to means which, during operation, force the needle holder in said movement to and fro. These means comprise an arm 21 which is fixed to the needle holder in a manner such that it can be hinged and whose other extremity emanates in a jaw 22. The jaw 22 receives a camshaft that is assumed to be sufficiently well known so as not to require further drawing here, which camshaft operates together with the jaw in order to force the extremity to move to and fro in a direction perpendicular to the direction 23 of the arm. The arm carries a cam 24 which is received in a more or less well-fitting manner in a groove 25 which has been introduced in a body 26 which is connected to a fixed portion 100 of the device; see also figure 6. The groove 25 in the body 26 extends along a non- perpendicular angle to the direction 23 of the arm. The forward and backward motion of the extremity 22 forces the arm into an oscillatory motion in the direction 23 of the arm, the amplitude of which oscillation determines the final stitch bite. This amplitude is proportional to the cosine of the aforementioned angle of the groove 25 with respect to the arm 21. Because the body if affixed in a manner such that it can be hinged around a hinge axis 27, this angle of the groove can be adjusted as desired, so that in this manner the width of the stitch is easily adjustable. To this end, the body 26 is slightly loosened with a knob 28 (see figure 3, 5 and 6) and is moved in the direction of arrow X into the hole 29. Allen key bolts 30, in purposely made borings 31, or else other means, limit thereby the degree to which the body 26 can be hinged on opposite sides between a first extremity position and a second extremity position. The body 26 with the groove 25 is, in turn, adjustably mounted in a groove 32 of a further body 33. This groove 32 also subtends a non-perpendicular angle to the direction 23 of the arm. By adjusting the first body 26 with hinge element 27 in an axial direction according to the direction indicated with arrow Y in figure 4, an offset can be set and thereby also the spacing CS in the button hole. The extremity positions of the first body 26 and the height of the first body 26 in this further groove 32 can be mutually adjusted with the Allen key bolts 30 and a further bolt 34 and slide hole 35, respectively, in such a manner that, in one extremity position, the machine produces a relatively wide stitch bite SB that largely misses any spacing CS (for purposes of creating a 'cut after' button hole), while, in the other extremity position, a somewhat narrower stitch bite SB, in combination with a sufficiently wide spacing CS, is produced for purposes of manufacturing a 'cut after' button hole. With the aid of the knob 28, the machine can be switched between both extremity positions in a very simple manner, whereby altering the button hole mode can be done in a very user-friendly way. No special additional tools are required for this, nor is a service technician required. The person who normally operates the machine can perform everything independently. Although the invention has been further elucidated and described solely on the basis of this one exemplary embodiment, it shall be obvious that the invention is in no way limited thereto. On the contrary, for a person skilled in the art, there are, within the scope of the invention, still many variations and other implementations possible, all of which embody a common inventive line of thought and are thereby assumed to be included within the scope of the current invention. As such the adjustability of the stich bite and cutting space may be realised in a similar fashion elsewhere along the length of the cam shaft, for instance at the opposite end of it near the element 20 which receives the needle bar holder.

Claims: Claims: 1. Industrial sewing machine for the completion of a button hole in a fabric, which button hole may or may not have been already opened, comprising a needle holder for the purposes of receiving a needle therein, which needle holder is coupled via an arm to means which, at least during operation, force the needle holder to move forward and backward substantially transverse to the direction of the needle, characterised in that said means comprise oscillation means which, at least during operation, cause an extremity of the arm turned away from the needle holder to move to and fro substantially transverse to the direction of the arm, in that the arm carries a cam which is received in a groove of a pivotably suspended first body, which groove extends under a non-perpendicular angle to the axial direction of the arm, and in that said first body is adjustably fixed in a groove of a further body that is connected to a fixed portion of the device, which groove of said further body also extends under a non-perpendicular angle to the axial direction of the arm. 2. Industrial sewing machine according to claim 1 , characterised in that the arm, at its side facing away from the needle holder, comprises a jaw which is capable of operation together with a camshaft, which camshaft is driven, at least during operation, in such a manner that the aforementioned extremity is forced to move to and fro perpendicular to the direction of the arm. 3. Industrial sewing machine according to claim 1 or 2, characterised in that the degree to which the body can be hinged is limited between previously determined first and second extreme positions. 4. Industrial sewing machine according to claim 3, characterised in that the first body is adjustably fixed in the groove of the further body in such a manner that the machine produces a rather wide stitch bite and hardly no cutting space in a first extreme position of the first body and a smaller stich bite together with a certain cutting space in the second extreme position of the first body.

Inventors: KOSMAS NIKOLAOS, KOSMAS, NIKOLAOS
Applicants: ELECTRIN HOLDING N V, KOSMAS NIKOLAOS, ELECTRIN HOLDING N.V., KOSMAS, NIKOLAOS
Application year: 1997
Main classification: D05B3
IPC codes: D05B3