JP5286170B2 - Hook for double lock stitch machine - Google Patents

Abstract

The gripper e.g. double-backstitch gripper (8), has a bobbin case (21) arranged in a cap-shaped gripping body (24) about an axis (9) and including a base (34) and a bearing pin (25). A gripper thread bobbin (26) is movably arranged on the pin in a direction of the axis, and includes flanges (28, 29) that are spaced apart from each other, where the flanges are connected to a hollow boss (27). A brake spring and an exhaust spring i.e. cylindrical helical spring, enclose the pin, and the case is reinforced at a region of the base, and the bobbin is reinforced in an opening (31) of the boss.

Description

  The present invention relates to a hook for a double lock stitch machine comprising a cup-shaped hook body having a bobbin case attached to the hook body for rotation about an axis, the bobbin case comprising a bearing pin concentric with the shaft And a bottom portion.

  In this type of hook known from Patent Document 1 (corresponding to Patent Document 2, Patent Document 3 and Patent Document 4), a brake and discharge spring is provided adjacent to the bottom of the bobbin case and the bobbin. It is arranged between the flanges. The brake / discharge spring has a truncated cone shape, and when the hook thread bobbin is inserted into the bobbin case, the spring can be compressed to the thickness of the winding. With this spring it is extremely difficult to achieve on the one hand an optimum discharge path for the bobbin and on the other hand a constant brake torque to be applied to the bobbin during operation.

DE19510830C2 JP Hei08-59489 KR 7521/1996 CH ZL 96104262.1

  The object of the present invention is configured to ensure on the one hand a constant brake torque and thus a constant hook thread tension and on the other hand a large discharge path for the hook thread bobbin from the bobbin case. It is to provide a general type of simple configuration hook.

  This object is achieved according to the invention by the features of claim 1. The gist of the present invention is that a substantially cylindrical helical spring is used as a brake / discharge spring that engages a corresponding recess in the hub of the hook thread bobbin. The brake / discharge spring as described above does not have to be a cylinder in a strict mathematical sense. What is important is to have enough space in the recess of the hook thread bobbin. Accordingly, the spring may have a slightly barrel shape or a slightly conical shape. This spring is therefore relatively long and allows a long discharge path. On the other hand, the brake torque can be adjusted very accurately with this kind of spring, thus ensuring that the hook thread is rewound steadily. In addition, the space between the bobbin flange facing the bottom of the bobbin case and the bottom generally allows an increase in the size of the bobbin, as space is no longer needed due to the described spring in the shape of a truncated cone. To do.

  Further advantageous embodiments are listed in the dependent claims.

It is the side view of the sewing machine partially opened. Fig. 4 shows a hook according to the present invention along the section II-II of Fig. 3, into which a movable hook thread bobbin is inserted. FIG. 3 is a plan view of the hook described in FIG. 2. The hook shown in FIG. 2 is shown along line IV-IV in FIG. 5, and the hook thread bobbin is discharged. It is a top view of the hook described in FIG. Figure 3 is a longitudinal section through an improved embodiment of a hook yarn bobbin. FIG. 7 is a plan view of the hook yarn bobbin described in FIG. 6. It is a cylindrical brake and discharge spring suitable for the hook thread bobbin described in FIG.

  Further features, advantages and details of the invention will become apparent from the following description of embodiments of the invention, using the drawings.

  The double-lockstitch sewing machine shown in FIG. 1 conventionally comprises an upper arm 1, a vertical stand 2 and a housing-like lower base plate 3. An arm shaft 4 is attached to the arm 1, and a needle bar 5 including a needle 6 can be moved up and down using the arm shaft 4. Furthermore, the arm shaft 4 moves the thread lever 7.

  A vertical hook 8, that is, a double lock stitch hook 8, is attached to the base plate 3, and the hook 8 can be driven for rotation around the vertical axis 9. A hook drive shaft 10 that carries a hook 8 and is rotatable about a shaft 9 is attached to a hook bearing housing 11 disposed on the base plate 3 for rotation. The hook drive shaft 10 is driven by a transmission shaft 12 using a bevel gear 13. The transmission shaft 12 is also driven by the arm shaft 4 using a toothed belt drive 14. The toothed belt drive 14 has a 1: 1 speed transmission ratio. The bevel gear 13 is dimensioned so that a 1: 2 speed transmission ratio is achieved. This means that the hook 8 rotates twice during each rotation of the arm shaft 4 or the transmission shaft 12. To accomplish this, the large drive bevel gear 15 disposed on the transmission shaft 12 has twice as many teeth as the drive bevel gear 16 disposed on the hook drive shaft 10.

  Above the hook 8, a needle plate 17 having a needle hole 18 is fixed to the upper side of the base plate 3. The hook 8 has a hook tip 19, and the hook tip passes directly through the needle 6 inserted in the needle hole 18 and can catch the needle thread 20 guided by the needle 6. A bobbin case 21 is attached to the hook 8, and the bobbin case can freely rotate around the shaft 9 with respect to the hook 8. The annular bearing collar 22 of the bobbin case 21 abuts on a bearing ring 23 disposed on the cup-shaped hook body 24 of the hook 8. Since the bobbin case 21 is attached by a normal method, the needle thread 20 caught by the hook tip 19 is guided around the bobbin case 21.

  As can be seen from FIGS. 2 to 4, the bobbin case 21 is also substantially cup-shaped. The bobbin case 21 has a hollow bearing pin 25 that is the central longitudinal axis 9 of the hook 8 and the hook drive shaft 10 and is concentric with the shaft 9 that is also the axis of the bobbin case 21. The hook bobbin 26 is received. The hook yarn bobbin 26 is conventionally provided with a hollow hub 27, an upper flange 28 and a lower flange 29. The bobbin 26 is provided with a source of hook thread 30 before being removed from the bobbin case 21 and reinserted into the bobbin case 21.

  An annular cylindrical recess 31 is formed in the hub 27 of the bobbin 26, and the cylindrical recess opens inward in the direction of the bearing pin 25. A brake / discharge spring 32 in the form of a cylindrical helical spring is disposed in the recess 31, and the cylindrical helical spring is supported by an annular groove 33 in the bottom 34 of the bobbin case 21, and an annular collar 33 a is provided. And centered with respect to the axis 9. In the hub 27 of the bobbin 26, the spring 32 is supported with respect to the stopper or stopper 31a.

  A locking device 35 is formed by a locking lever 36, which is pivotally attached to the hollow bearing pin 25 and comprises two contact surfaces 37, 38 that are offset by 90 °. These contact surfaces 37, 38 are attached to the recesses 39 of the bearing pins 25 for displacement in the direction of the shaft 9 and are applied against one of the contact surfaces 37 or 38 using a preloaded helical compression spring 41. Assigned to the counter bearing 40 to be pressed. The contact surface 37 of the lever 36 abuts against the counter-bearing 40 when the lever 36 rotates about 90 ° with respect to the shaft 9, so that the bobbin 26 is placed at the bottom of the bobbin case 21 as shown in FIG. Toward the position 34, it is displaced opposite to the force applied by the brake / discharge spring 32. The contact surface 38 abuts against the counter-bearing 40 when the lever 36 extends approximately in the direction of the shaft 9, in other words when the locking device 35 is released, and the bobbin 26, as shown in FIG. Then, the bobbin case 21 is discharged by the brake / discharge spring 32. In this position, the bobbin 26 can be removed from the bobbin case 21 by the operator. The comparison between FIG. 2 and FIG. 4 is that when the bobbin 26 is inserted, the brake and discharge spring 32 is compressed to the maximum extent possible and when the locking device 35 is opened, the spring 32 This means that the bobbin 26 can be easily gripped because the bobbin 26 is discharged from the bobbin case 21 substantially upward. As also shown in FIGS. 2 and 4, the recess 31 extends in the direction from the lower flange 29 to the upper flange 28 over approximately ¼ of the extension of the bobbin 26 in the direction of the axis 9. However, the recess 31 may span up to half of this axial extension, i.e. especially when the gap between the lower flange 29 and the bottom 34 is reduced in size.

  As shown in FIGS. 2 and 4, the bobbin 26 comprises a so-called entrainer groove 42 in its upper flange 28, strictly speaking, in the region near the hub 27, said tuning groove 42. Is required for rotationally driving the bobbin 26 in a winder for winding the hook yarn 30. This tuning groove 42 is engaged with the tuning element of the hoist to ensure positive rotational drive engagement.

  A sliding bearing 43 is formed radially outward of the tuning groove 42 between the locking lever 36 and the flange 28 of the bobbin 26, and each time the locking lever 36 passes the tuning groove 42 during operation of the hook 8, This prevents the bobbin 26 from being obstructed from uniform and uniform free rotation. When the lever 36 and thus the bobbin 26 in the bobbin case 21 is in the locked state, the lever 36 and the upper flange 28 are thus pressures configured as an annular surface area 44 of the flange 28 and an elevation of the lever 36. Only in contact with each other at the surface 44a, a constant pressure is always provided by the compressed cylindrical brake and discharge spring 32. The friction torque, and hence the braking torque between the locking lever 36 and the hook thread bobbin 26, is therefore also constant during one revolution of the bobbin 26.

  The sliding bearing 43 is adjacent to a recess 45 in the lever 36 in the radially outward direction, and the recess 45 serves as a recess gripping part. In order to move the locking lever 36 from the bent position illustrated in FIG. 2 to the open position illustrated in FIG. 4, the operator does not need to use an instrument or tool and the upper flange 28 of the bobbin 26 and the lever 36. The lever 36 can be grabbed between them.

  As can be seen from FIGS. 3 and 5, a longitudinal hole 47 extending radially towards the outer rim 46 of the flange 28 is continuously formed relatively close outside the annular surface region 44, The longitudinal holes 47 are evenly distributed over the periphery. These extend to the hub 27 but do not reach the annular surface region 44 of the flange 28. These longitudinal holes 47 allow a very accurate observation of the source of hook thread 30. Furthermore, they reduce the mass and thus the moment of inertia of the bobbin 26.

  The hook thread bobbin 26a shown in FIGS. 6 and 7 includes a recess 31b in the form of an annular groove engaged by a brake / discharge spring 32a as shown in FIG. 2 and 4 are all provided with a winding 48 having the same diameter, while the brake / discharge spring 32a has a reduced diameter 1-2 in the lowermost region. The other winding 48 has a larger diameter because it comprises a single winding 48a and the recess 31b is configured as an annular groove and therefore has a larger diameter compared to FIGS. The spring 32 can be centered on a similar annular collar 33a. 6 and 7 has the advantage that the entire guide length of the hook thread bobbin 26a in the bearing pin 25 of the bobbin case 21 is maintained despite the annular recess 31b for the brake and discharge spring 32a. Have.

  As also shown in FIGS. 6 and 7, the sliding bearing 43 can be configured such that the annular surface region 44b is a ridge on the upper flange 28 of the hook thread bobbin 26a. In this case, the pressure surface 44a can be formed on the locking lever 36 (but not necessarily).

9 Shaft 21 Bobbin case 24 Cup-shaped hook body 25 Bearing pin 26 Hook thread bobbin 26a Hook thread bobbin 27 Hub 28 Flange 29 Flange 31 Recess 31b Recess 32 Brake / discharge spring 32a Brake / discharge spring 33 Ring groove 33a Ring collar 34 Bottom 48a Winding

Claims (8)

Make a hook for the double lock stitch machine,
-A cup-shaped hook body (24);
A bobbin case (21) attached to the hook body (24) for rotation about an axis (9),
-Bottom (34),
A bobbin case (21) comprising a bearing pin (25) concentric with the shaft (9);
A hook thread bobbin (26, 26a) arranged on the bearing pin (25) for displacement in the direction of the shaft (9),
-Two flanges (28, 29) spaced apart from each other;
A hook thread bobbin (26, 26a) comprising a hollow hub (27) guided on the bearing pin (25) and interconnecting the flanges (28, 29);
-Brake and discharge springs (32, 32a),
-A substantially cylindrical helical spring,
-Surrounding the bearing pin (25),
-On the one hand, supported in the region of the bottom (34) of the bobbin case (21),
-On the other hand, brake and discharge springs (32, 32a) supported in the recesses (31, 31b) of the hub (27) of the hook thread bobbins (26, 26a);
A hook comprising:   The hook according to claim 1, characterized in that the brake / discharge spring (32, 32a) is supported in the annular groove (33) at the bottom (34) of the bobbin case (21).   Hook according to claim 1 or 2, characterized in that the brake and discharge spring (32, 32a) is centered with respect to the bobbin case (21) using an annular collar (33a).   The brake / discharge spring (32, 32a) contacts the stopper (31a) at the recess (31, 31b) of the hub (27) of the hook thread bobbin (26, 26a). The hook as described in any one.   5. Hook according to any one of claims 1 to 4, characterized in that the recess (31, 31b) extends from 1/4 to 1/2 of the hub (27) in the direction of the axis (9). .   Hook according to any one of the preceding claims, characterized in that the recess (31) opens towards the bearing pin (25) of the bobbin case (21).   Hook according to any one of the preceding claims, characterized in that the recess (31b) is an annular groove in the hub (27) of the hook thread bobbin (26a).   Brake and discharge spring (32) comprising at least one winding (48a) at one end, said winding (48a) being adapted to an annular collar (33a). 3. The hook according to 3.

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