Sewing machine horn

Abstract: A lockstitch sewing machine horn incorporates a drive shaft arranged to rotate a whirl, the horn being divided into segments (9,11,13) by a plurality of pivoted joints (12,14), each joint being associated with a flexible joint in the drive shaft located within the horn, and with locking means (24), such that the horn can be selectively locked in two or more positions, each position having a different angle subtended between the longitudinal axis of the uppermost segment of the horn and the axis of travel of the needle while maintaining the tip of the horn in a substantially fixed position.

Description: This invention relates to a sewing machine horn, particularly for a lockstitch machine for use in the manufacture or repair of footwear, bags, cases, sports balls and equipment in any application where heavy duty stitching is required (see by example US-A-2 354 468). Sewing machines for use in the manufacture and repair of footwear conventionally comprise an upright machine having at the top a head in which is mounted the needle, a shuttle and a pressure foot and the asssociated drive means for them, this head been located immediately above a curved "horn" having a tip through which the needle reciprocates and from which the complementary thread is dispensed by means of a rotating bevel gear with a concentric hole for the needle to pass through and an eccentric hole for the thread to pass through, known as a whirl, driven by a drive shaft located within the horn. Obviously, the tip of the horn must be precisely located in relation to the needle and, in practice, it takes a skilled engineer some time to set up such a machine. However, for different purposes, different configurations of the horn are required. Thus, a distinctly curved horn having a lower part which is substantially upright and an upper part which is inclined at about 35° to the horizontal is required for sole stitching, whereas a straighter horn having an upper part inclined at about 70° to the horizontal is required for sidewall stitching. In conventional practice, machines are provided with two or more entirely separate horns and when a different operation of the machine is required, one horn is dismounted and the other horn installed. Because of problems with alignment and disconnection and reconnection of the drive shaft, this precedure is far from simple. There is thus a need for a simplified system where a single horn can be adapted for different modes of action. The present invention is based on the provision of a jointed horn capable of providing a range of configurations. According to the present invention there is provided a lockstitch sewing machine horn incorporating a drive shaft arranged to rotate a whirl, through which a needle can reciprocate in use, the horn being divided into segments by a plurality of pivoted joints, each joint being associated with a flexible joint in the drive shaft located within the horn, and with locking means, such that the horn can be selectively locked in two or more arrangements, each arrangement having a different angle subtended between the longitudinal axis of the uppermost segment of the horn and the axis of travel of the needle while maintaining the tip of the horn in a substantially fixed position. In principle, an appropriate combination of joints and locking means will provide different horn configurations, in each case with the tip exactly in the same location relative to the needle. However, as the angle of the upper part of the horn is changed, so the tip angle must also be changed. It will be understood that the tip itself has an upper surface which is essentially horizontal (i.e. perpendicular to the travel of the needle) and is thus at an angle to the supporting upper part of the horn. This angle is referred to herein as the tip angle. To overcome this problem, the apparatus is suitably provided with a selection of separate tip segments, each having a different tip angle, for use in the different selected positions. Variations in the lengths of these tip segments make it easier for the exact location of the tip to be achieved. In a particularly preferred embodiment, the horn comprises three pivoted joints: one at the bottom end, preferably for connection to a boss rotatable about a vertical axis; and two intermediate pivoted joints in the manner of elbows to provide the required configuration. Each pivoted joint is provided with locking means arranged to lock the joint in one of two or more positions. For preference the machine is arranged to be adaptable between two chosen positions. Any convenient locking means can be used, for example locking pins for cooperation with two or more holes. Each joint will of course be associated with a flexible joint in the drive shaft, typically a "universal" joint and, preferably, such joints are double joints. To set the horn in the first chosen position, the locking means at each joint is released, for example, the locking pin is withdrawn from a hole, the appropriate configuration is achieved, and the locking means then locked for that configuration. Advantageously, each locking position is clearly labelled. The appropriate tip segment is then installed, by connecting it to both the uppermost horn section and to the drive shaft. A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 represents a general view of a lockstitch sewing machine fitted with a conventional horn; Figure 2 and Figure 3 represent simplified views of the horn according to the invention; Figures 4a and 4b represent sectional views of the tip section of the horn according to the invention; Figure 5a represents a partial view of a typical joint; and Figure 5b represents an elevation of a typical universal joint in the drive shaft. With reference to Figure 1, the stitching machine comprises a head 1, on which are mounted a shuttle 2, a pressure foot 3 and a reciprocating needle 4, powered by drive means within the head (not shown). A base cabinet 5 contains the main power source for driving the head components and the horn components. Mounted on the base cabinet 5 is a horn 6 arranged for rotation about a vertical axis on a boss 7. The tip of the horn 8 contains a whirl through which the needle can reciprocate. In the apparatus according to the invention, the horn 6 comprises 3 segments. As shown in Figures 2, 3, 4a and 4b a bottom segment 9 is mounted, via pivot 10, on the boss 7. A middle segment 11 is mounted on the upper end of the lower section 10 by means of a pivot joint 12, and an upper segment 13 is mounted on the upper end of the middle segment 11 by means of a pivot joint 12'. Each segment 9, 11, 13 is of hollow construction and houses corresponding portions of a drive shaft 14. At each joint, the drive shaft incorporates a double universal joint (see Fig. 5a) comprising shaft length compensation means 15.. The upper segment 13 incorporates interchangeable tip segments 16, 17 incorporating a whirl 18 and having different tip angles and different lengths. As shown in Figures 4a and 4b, the tip segments 16, 17 are provided with a neck 25 adapted to locate in a corresponding socket 26 in the upper segment 13 where it is secured by a locking screw (not shown). The tip of the drive shaft 14 is provided with a transverse slot 27 adapted to cooperate with a corresponding tang 28 in the end of the driven shaft. As shown in Fig. 5a, a typical pivot joint 12, associated with locking means, in the form of a first transverse bore 21 through one pivoted segment and two mutually parallel complementary bores 22, 23 in the other pivoted segment, each of the complementary bores being arranged to align with the first transverse bore in one of the two configurations shown in Figures 2 and 3, and a locking pin 24 is provided to pass through the aligned bores. Angles are chosen such that in each configuration, the position of the tip whirl is in the same place relative to the base and to the needle axis. In general, each of the segments 9, 11, 13 can be formed of steel or other appropriate alloy. It would be appreciated that this leads to a much easier construction than the previous use of a cast horn which requires elaborate angled milling and drilling operations to house the drive shaft. In the configuration shown in Figure 2, the angle between lower segment 9 and the horizontal is about 100°; the angle between segments 9 and 11 approximately 180° and the angle between segments 11 and 13 approximately 125°. In the configuration shown in Figure 3, the three angles are approximately 156°, 94° and 180° respectively. Other configurations can be envisaged, depending on the mode of use of the sewing machine to which the horn is to be fitted.

Claims: A lockstitch sewing machine horn (6) incorporating a drive shaft (14) arranged to rotate a whirl (18) through which a needle (4) can reciprocate in use, the horn (6) being divided into segments (9, 11, 13) by a plurality of pivoted joints (10, 12, 12'), each joint being associated with a flexible joint in the drive shaft (14) located within the horn (6), and with locking means (21, 22, 23, 24), such that the horn (6) can be selectively locked in two or more arrangements, each arrangement having a different angle subtended between the longitudinal axis of the uppermost segment (13) of the horn (6) and the axis of travel of the needle (4) while maintaining the tip of the horn (6) in a substantially fixed position. A horn according to claim 1, provided with a set of separate tip segments (16,17), each having a different tip angle, for use in the different selected positions. A horn according to Claim 1 or claim 2 wherein three joints (10,12,12') are provided in the horn (6) such that the horn can be locked in a first position suitable for use in the stitching of the soles of footwear and in a second position suitable for use in stitching the sidewalls of footwear. A horn according to any of Claims 1 to 3 wherein locking means is provided for each joint in the form of a locking pin (24) and two or more corresponding holes (22,23). A horn according to Claim 4 wherein each joint (12,12') has two positions into which it can be locked by means of said locking pin (24).

Inventors: GREASELY MICHAEL JOHN, RICHARDS JOHN STUART, GREASELY, MICHAEL JOHN, RICHARDS, JOHN STUART
Applicants: STANDARD CRESSALL LTD, STANDARD CRESSALL LIMITED
Application year: 1995
Main classification: D05B73
IPC codes: D05B73, D05B15