GB2311302A - Sewing machine horn - Google Patents

Abstract

A horn for a lockstitch sewing machine for sewing footwear or other heavy duty applications comprises a fixed lower part (13) formed as a tube with a drive shaft (27) therein and an interchangeable upper part (10) which makes an in-line push-fit connection with the lower part by means of a joint (14) and which contains a drive shaft (23) which makes a push-fit connection (25,26) with the drive shaft (27) and drives a whirl (19) in a horn tip section (17). The upper part (10) may be replaced by another having a different configuration and presenting the horn tip at a different angle.

Description

Sewing Machine Horn 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.

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 associated drive means for them, this head being 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. In order to provide appropriate rigidity and precise location of the whirl relative to the needle, the conventional horn is constructed as a single hollow casting through which the jointed drive shaft runs.

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 or the drive shaft, this procedure is far from simple.

In answer to this problem, EP-A-0678612 disclosed a simplified system where a single horn can be adapted for different modes of action, by provision of a jointed hom capable of providing a range of configurations. In that system the lockstitch sewing machine horn incorporated a drive shaft arranged to rotate a whirl, 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 could 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.

In principle, an appropriate combination ofjoints 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. at right angles 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.

Thus, the previous system worked on the principle of adapting the horn by manipulation of adjustable joints, but still required replacement parts.

There is thus still a need for a simple system allowing quick and easy transition from one form to another, depending on the needs of the machine and the workload.

We have now devised a simple plug-in arrangement which solves the problem.

According to the present invention, the horn comprises two main parts: a lower, fixed part common to both (or all) arrangements, and an upper, removable part selected from two or more varied configurations, the two parts being simply pushed together to fit and lock. The lower part comprises a stiff metal tube defining an axially extending duct, typically of mild steel and preferably of oval cross-section, and having at an upper-end a simple push-fit joint means and at the bottom end being capable of secure attachment to the base of the sewing machine. Associated with the lower part is a lower drive shaft arranged at a lower end for geared connection to the main drive means of the sewing machine, while at an upper end being provided with means for in-line, push-fit connection to a further drive shaft. The lower drive shaft is located within the lower part and is of similar axial length.

Each upper part comprises a tubular lower section defining an axially extending duct, and being of matching profile to that of the lower part, the lower section being provided at its lower end with push-fit joint means complementary to that of the upper end of the lower part; a middle section set at an angle to the lower section and also defining an axially extending duct, the middle section tapering to an upper tip section incorporating a rotating bevel gear and whirl. Each upper part has located in the duct an upper drive shaft which is provided at its lower end with complementary in-line, push-fit joint means for connection to that of the lower drive shaft and at its upper end being arranged to drive the rotating bevel gear. At an intermediate point along its length the upper drive shaft comprises a flexible joint to allow the shaft to traverse the angle in the upper part.

The upper part is conveniently constructed of tubular metal, typically mild steel, but may be of U-shaped cross-section or other suitable hollow configurations. The joint between the lower and middle sections is conveniently a weld. The tip section is conveniently constructed of hardened steel in the conventional way and is arranged so that the bevel gear and whirl are on a substantially vertical axis (i.e. rotate in a horizontal plane).

The flexible joint in the upper drive shaft is preferably a "universal" joint, desirably incorporating a double swivel. The in-line push-fit joint means may typically comprise complementary male and female parts arranged to transmit rotational force. Preferably a conventional square plug and socket arrangement (as in a socket screwdriver) or a blade and slot arrangement (as in a standard screw and screwdriver) is used. Because of the fixed in-line formation, it is not necessary to prevent relative axial movement between the two parts, although a simple ball-catch device as used in socket screwdriver joints could be used.

The push-fit joint means between the upper and lower main parts typically comprises a simple bushed plug and socket system, where a rebated tubular bushing extends from one part to be received axially within the bore of the other part. The joint may be secured against both axially and rotational movement by a simple radial locking pin or grub-screw.

The choice of upper part will depend on the current use of the sewing machine. For shoe manufacture or repair the choice is generally between a relatively bent upper part for forepart sole stitching and a relatively straight upper part for sidewall stitching.

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 one embodiment of the horn of this invention; Figures 2 and 3 represent two embodiments of the lower section of the upper horn part; Figure 4 represents the lower part of the horn; and Figure 5 and Figure 6 represent part sectional views of the horn incorporating the upper parts shown in Figures 2 and 3 respectively.

With reference .o Figure 1, the stitching machine comprises a head 1 on which is mounted a shuttle 2, a pressure foot 3 and a reciprocating needle 4, powered by a drive means within the head (not shown). A base cabinet 5 contains the main power source for driving the head 1 and the horn 6 components, the power source and the pressure foot 3 being controlled by foot pedals 7 on the base cabinet 5. A horn 6 is mounted on the base cabinet 5, and is rotatable about a vertical axis on a boss 8.

The tip of the horn 6 contains a whirl through which the needle can reciprocate. The needle is driven by a belt drive 9, which can be adjusted manually by means of handwheel 9A so as to move the needle through its cycle, to a desired position.

With reference to Figures 2, 3 and 4, the horn 6 has two main parts, a lower part 13 and an upper part 10. The upper part 10 has two sections, a lower section 10a and a horn tip section 17 (not shown). The two parts of the horn 6 being of a fixed configuration, the outer construction consisting of a generally oval-sectioned tubular steel casing, which may in part be U-shaped in configuration. The upper part 10 comprises tubular sections which are welded at angles to one another to create a fixed-angle horn. In Figures 2 and 3 the lower section 10a of the horn has an opening 11 in its outer casing, provided with a removable cover plate (not shown), to allow access to the mechanics inside. The lower section 10a has a push-fit joint 12 with which it can be attached to the lower horn part 13 by a bushing 14, as clearly seen in Figure 4. The lower end of the horn part 13 is connected to a base 15 by a bushing 16.

With reference to Figures 5 and 6, the interchangeable upper part 10 comprises of two sections, a horn tip 17, which is fitted to a lower section 10a. The upper part 10 is attached to the lower part 13 by a bushing 14. Upper parts 10 have different angles and different lengths. The horn tips 17 also have different angles and lengths. The lower part 13 is inclined at an angle and is connected to a base 15 by a bushing 16. As shown in Figures 5 and 6, the horn tip 17 has a tail 18 which is secured to the lower section 10a.

The horn tip 17 incorporates a whirl 19 which is arranged to be driven by a drive shaft 20. The lower end of the drive shaft 20 is provided with a tang 21 which is shaped so as to fit securely in a transverse slot 22 on the upper end of a drive shaft 23. To accommodate the bend in the upper part 10, the drive shaft 23 is fitted with a double pivot "universal" joint 24.

The upper horn part 10 is attached to the lower horn part 13 by a push-fit joint comprising a bushing 14 which is fitted inside the lower horn part 13 so as to protrude and form a plug, capable of being received in the upper part 10 and locked into position by a screw. The lower end of the drive shaft 23 is provided with a tang 25 which is arranged to fit into a transverse slot 26 on the upper end of the drive shaft 27. The lower end of the drive shaft 27 is provided with a bevel gear 28 contained in the base 15, the lower horn part 13 being attached to the base 15 by a bushing 16.

Figures 5 and 6 are different from each other, in that the upper parts 10 have configuratively different set angles and lengths and contain different horn tips 17.

Figure 5 also contains a cover 29 over the 11 in its upper part 10, which is secured by means of screws 30.

In use, the operator chooses the appropriate upper horn part 10 and attaches it to the lower horn part 13 and locks them together with a grub screw. The horn is then threaded through eyelets, up along its side, to the horn tip 17. The needle is manually positioned in it's cycle by means of the handwheel 9A, thus allowing the material to be positioned on the horn and sewn. When the operator wishes to perform a different sewing task, a different horn configuration may be required. The upper horn part 10 is interchanged by unthreading it, removing the screw and disconnecting the upper horn part 10, at the push-fit joint, from the fixed lower part 13, thus allowing the appropriate horn part 10 to be fitted to the machine quickly and with only minor adjustments.

Claims (10)

CLAIMS:

1. A sewing machine horn comprising two main parts: a lower, fixed part common to both (or all) arrangements, and an upper, removable part selected from two or more varied configurations, the two parts being simply pushed together to fit and lock, the lower part comprising: a stiff metal tube defining an axially extending duct, having at the upper end a simple push-fit joint means and at the bottom end being capable of secure attachment to the base of the sewing machine; and, associated therewith a lower drive shaft arranged at a lower end for geared connection to the main drive means of the sewing machine, while at an upper end being provided with means for in-line, push-fit connection to a further drive shaft, the lower drive shaft being located within the lower part and being of similar axial length; each upper part itself comprising: a tubular lower section defining an axially extending duct, and being of matching profile to that of the lower part, the lower section being provided at its lower end with push-fit joint means complementary to that of the upper end of the lower part; a middle section set at an angle to the lower section and also defining an axially extending duct, the middle section tapering to an upper tip section incorporating a rotating bevel gear and whirl; each upper part having an upper drive shaft located in the duct, which drive shaft is provided at its lower end with complementary in-line, push-fit joint means for connection to that of the lower drive shaft, at its upper end being arranged to drive the rotating bevel gear; and an intermediate point along its length comprising a flexible joint to allow the shaft to traverse the angle in the upper part.

2. A sewing machine horn, as claimed in Claim 1, in which the push-fit joint is a bushed joint.

3. A sewing machine horn, as claimed in Claim 1, in which the metal tube is made of tubular steel.

4. A sewing machine horn, as claimed in Claim 1, in which the tube is of oval cross-section.

5. A sewing machine horn, as claimed in Claim 1, in which the push-fit joint is secured by means of a screw.

6. A sewing machine horn, as claimed in Claim 1, in which the push-fit joint is secured by means of a locking device.

7. A sewing machine horn, as claimed in Claim 1, in which the flexible joint, is a double axis "universal" joint.

8. A sewing machine horn, substantially as herein described, with reference to the accompanying drawings.

9. A sewing machine, including a horn, as claimed in any of Claims 1 to 8.

10. A sewing machine, substantially as herein described, with reference to the accompanying drawings.