WO2011131335A1

WO2011131335A1 - Looper device having improved friction behaviour

Info

Publication number: WO2011131335A1
Application number: PCT/EP2011/001972
Authority: WO
Inventors: Joachim Richter
Original assignee: Pfaff Industriesysteme Und Maschinen Ag
Priority date: 2010-04-21
Filing date: 2011-04-19
Publication date: 2011-10-27
Also published as: DE102010017897A1

Abstract

The invention relates to improving the wear behaviour in a looper device for arrangement in a sewing machine, comprising a looper body having a looper tip, wherein the looper body is provided in the sewing machine for rotation about an axis of rotation and has a receptacle for arrangement of a bobbin case holder in the looper body, and the bobbin case holder and the looper body are provided with guide means for mutual guidance during rotary movements of the looper body. According to the invention, at least one depression is provided on at least one surface of the guide means to receive lubricant.

Description

Gripper device with improved friction behavior

The invention relates to a gripper device for arrangement in a sewing machine, which has a gripper body with a gripper tip, wherein the gripper body is provided to a rotating rotational arrangement about an axis of rotation in the sewing machine and having a receptacle for arranging a bobbin case in the gripper body, the bobbin case and the gripper body are provided with guide means for mutual guidance during rotational movements of the gripper body.

Sewing machines form seams using an oscillating reciprocating needle which guides an upper thread and a gripper device guiding a lower thread. In particular, the gripper devices of lockstitch sewing machines are provided with a bobbin case carrier, which are arranged in a receptacle of the gripper body of the gripper device. The bobbin case takes on a coil on which the bobbin thread is wound. In lockstitch sewing machines, the gripper body performs in the formation of a seam with respect to its speed to the frequency of the oscillating movement of the needle coordinated rotating movement about a usually vertical drive axis. The spool and its bobbin case carrier are fixedly arranged in the gripper body in this rotating movement of the gripper body. Since it is necessary that in the rotary movement of the gripper body, the coil is aligned in a certain way relative to the gripper body, both elements are provided with coordinated guide means. Usually, the gripper body on its wall bounding the receptacle on the inside of a gripper track which extends around the axis of rotation of the rotational movement. Often the gripper track is designed as a circumferential groove on the boundary wall of the recording. The bobbin case is, however, provided at its outer periphery with a corresponding to the cross-sectional shape of the groove web, which is arranged in the groove. In order to reduce the wear caused by the friction of the guide means and the development of heat, Schiermittel is fed into the receptacle of the gripper body. Previous gripper bodies therefore have a recess through which the lubricant is supplied. Both the

CONFIRMATION COPY Supply of the lubricant into the receptacle as well as its distribution in the receptacle to the guide means is made using centrifugal force. The centrifugal force causes lubricant to rise in a through-hole and thereby enters the receptacle. In this then the lubricant can be distributed to the outside to the guide means. Since the conveying effect is strongly dependent on the speed, a sufficient lubricant supply can not be ensured, especially at low speeds. As a result, premature wear of the gripper device may occur. This is especially true in applications in which a plurality of relatively short seams are produced in succession at short intervals and the sewing machine does not or only briefly reaches higher speeds in these sewing operations.

The invention is therefore based on the object to improve the wear behavior of the gripper device in a sewing machine with a gripper device of the type mentioned.

This object is achieved in a sewing machine with a gripper device of the type mentioned in the present invention that at least one recess for receiving lubricant is provided on at least one surface of the guide means of gripper body and / or bobbin case carrier. By virtue of the at least one depression in at least one of the surfaces provided for the mutual guidance of bobbin case carrier and gripper body, the lubricant conveyed into the gripper body can be better absorbed on the respective surface provided with the at least one depression. As a result, the surface can be better wetted with lubricant, and the resulting lubricant film between the mutually frictional surfaces of the guide means reduces the coefficient of friction between the contacting surfaces of the guide means. The advantages of the invention can be enhanced by a plurality of wells.

The better wetting of at least one of the surfaces of the guide means can also lead, in particular after a standstill of the sewing machine, to a lubricant film distributed as evenly as possible being available faster than heretofore. The recesses also allow the lubricant better at the respective Surface adheres and remains in the wells even at low speeds and at standstill of the sewing machine. As a result, when a start of the sewing machine immediately lubricant for lubricating the hook track of the gripper body and the web of the bobbin case is available and it does not have to wait for a promotion of lubricant, for example, by a dependent of the speed of the drive motor of the sewing machine conveying effect. Even at the time of machine startup, a basic supply of lubricant is thus already available. As a result, the wear behavior of the guide means between gripper body and bobbin case carrier can be significantly improved.

The recesses may have different geometric shapes, in principle, any geometric shapes are possible, which can be introduced into the respective surfaces of the friction partners, For example, slot-like slot-like recesses have proved to be favorable, the length of which is greater in the circumferential direction than the width.

The inventively provided at least one recess in at least one of the guide surfaces may be advantageously formed on the bobbin case, especially if this, as is usual, is provided with a circumferential ridge. The latter is easily accessible for processing, which is why the improvement of the friction behavior can be achieved with very little technical effort. In principle, each surface of the guide means between the gripper body and the bobbin case carrier may be provided with the at least one recess according to the invention, preferably with a plurality of recesses, which is in frictional contact with another surface. However, it is particularly preferred if at least one of the surfaces is provided with at least one recess whose orientation relative to the axis of rotation of the gripper body has a vertical component. In previously known guide means which can also be used in connection with the invention, these are axial surfaces of the guide means formed as a web of the bobbin case carrier, ie surfaces which are perpendicular to the axis of rotation according to their desired orientation. Because these areas are special are strongly friction loaded can be particularly favorable effect on the life of the bobbin case and gripper body with the inventive measure.

In a further embodiment according to the invention, the peripheral surface of the bobbin-side guide means can also be provided either alone or in combination with at least one of the axial surfaces of the bobbin case carrier with at least one depression, preferably with a plurality of depressions. This also makes it possible to improve the wear behavior of bobbin case carrier and gripper body.

In other embodiments of the invention, at least one surface of the guide means of the gripper body can also be provided with at least one depression, preferably a plurality of depressions, according to the invention. Usually, the gripper body side guide means is formed as a groove-shaped gripper track. The recesses may also be introduced here in at least one of the two axially extending side surfaces of the gripper track or in the radially circumferential groove base.

The preferably a plurality of recesses may be arranged one behind the other in the form of one or more rows on the respective surface of the guide means. The recesses may have a wide variety of geometric shapes, for example, be provided with a slot-like boundary line, which may follow in their longitudinal extent the radius of curvature of the respective surface of the guide means in a non-exhaustive list of other embodiments may also be provided a circular or elliptical shape, for example.

In a preferred embodiment of the invention, the recesses are introduced into at least one of the surfaces by means of a laser in the respective surface and have a depth with respect to the respective surface of preferably up to 2.5 mm, more preferably from a range of 3μητι to 0.3 mm. The depressions can also be introduced in other ways, for example by milling or by erosion. Further preferred embodiments of the invention will become apparent from the claims, the description and the drawings.

The invention will be explained in more detail with reference to embodiments shown purely schematically in the figures, in which:

1 shows a sewing machine in a partially sectioned view from the front.

2 shows a gripper device and a bobbin case carrier of the sewing machine, in a perspective exploded view;

FIG. 3 shows a gripper body of the gripper device from FIG. 2 in a view from below; FIG. FIG. 4 shows the gripper body from FIG. 3 in a plan view; FIG.

Fig. 5 is a sectional view of the gripper body;

Fig. 6 is a sectional view of the gripper body with inserted

Bobbin case base;

7 shows a partial view of a drive device for the gripper device;

Fig. 8 is a partial view of the drive device and the lubricant supply for the gripper device

9 shows a lubricant supply for the gripper device

FIG. 10 shows the bobbin case carrier from FIG. 6 in a perspective representation; FIG.

Fig. 1 1 of the bobbin case carrier of Figure 10 in a view from below.

Fig. 12 of the bobbin case carrier of FIG. 6 in a sectional and detailed view. In Fig. 1, an example of a trained as a double-stitch sewing machine sewing machine is shown in a highly schematic manner, the housing 1 has a lower housing-shaped so-called base plate 2, from which a stand 3 extends substantially vertically upwards. At an upper end of the stator, an arm 4 connects, which runs approximately parallel to the base plate 2.

The sewing machine has an arm shaft 7, which is mounted in the arm 4 and, as well as the other basic components of the sewing machine mentioned below, are possibly only partly or highly schematically represented in FIG. The arm shaft 7 drives an oscillating up and down movable needle bar 5, at the needle holder, a needle for receiving an upper thread can be attached. In the base plate 2, a gripper device 8 is arranged, whose rotational movement is synchronized with the oscillating movement of the needle holder 5. A bobbin thread is on a spool 1 1, which is arranged in a multi-part bobbin case carrier 12 (Fig. 5). The gripper device 8 leads this in a conventional manner, the upper thread around the bobbin case 12 so that it can form a seam together with the lower thread. Usually, the needle holder 5 and the gripper device 8 are driven by a common drive, namely a servo electric motor, not shown, whose rotational drive movement is translated to the needle bar 5 and the gripper device 8 in a certain ratio. 2 to 6 and 10 to 12 of the bobbin case 12 and the multi-part gripper device 8 is shown, the basic structure may correspond to previously known gripper devices. The gripper device 8 has a gripper body 14, which is provided with a central through-hole 15 in which a drive shaft 16 (FIGS. 7 and 8) for rotationally driving the gripper device 8 is arranged about the axis of the drive shaft. Here, the drive movement of the motor of the sewing machine is guided via a gear 17 to the drive shaft 16 and translated here. The axis of the drive shaft 16 is aligned parallel to the movement axis of the needle bar 5 and extends vertically in the intended direction of the sewing machine. As can be seen in particular from FIG. 2, the gripper device 8 has a cover segment 20 screwed onto a hollow-cylindrical boundary wall 19 by means of screws 21. A longitudinal extent of the cover segment 20 follows the arcuate curvature of the boundary wall 19, wherein the cover segment 20 extends approximately over an arc portion of about 180 ° of the boundary wall 19. The boundary wall 19 located in an upper section of the gripper body 14 is open at the top and has an opening at its circumference at one point, in the region of which a hook tip 22 is formed. A needle guard 18 bolted to the gripper body in front of the hook tip 22 protects the hook tip against mechanical damage.

The boundary wall 19 as well as a surface 23 orthogonal to the axis of the drive shaft 16 (FIG. 5) form a receptacle 26 for the multipart bobbin case carrier 12. In other than the illustrated embodiments, the bobbin case carrier can also be provided with a lower part and a top, which together form a cavity for receiving a coil, which is wound with the yarn supply for the bobbin thread. The lower thread is unwound in a conventional manner during the sewing process and used to seam with the upper thread.

The bobbin case carrier 12 has on its outer circumference on a circumferential ridge 25 which is provided for arrangement in a formed on the inner surface of the receptacle 26 between the boundary wall 19 and the covering 20 circumferential groove 27. The groove 27 has the function of a so-called gripper track, in which the web 25 of the bobbin case carrier 12 is guided during rotational movements of the gripper body 14 about its drive axis. The groove extends in relation to the axis of rotation of the drive shaft 16 along a circumferential line of the boundary wall 19. The cross section of the web 25 substantially corresponds to the cross section of the hook track 27 and is guided in the latter with the least possible play in both the radial and axial directions. The hook track 27 and the web 25 each ensure as a guide means a correct relative orientation of the spool with respect to the hook tip in the seam formation. in the Region of the cover segment 20 forms this together with the boundary wall of the gripper body 14 a portion of the groove 27.

In particular, in FIGS. 10 to 12 of the bobbin case 12 is shown with its web 25 which extends over part of the circumference of the outer surface 13 of the bobbin case carrier. The web has a rectangular cross-sectional shape, from which an upper and a lower axial surface 51, 52 and an outer radial surface 53 result. Both in the upper and in the lower axial surface 51, 52 a plurality of recesses 54 are introduced, which are arranged in two juxtaposed rows. The geometric shapes of the recesses 54 are substantially identical. In the illustrated embodiment, the recesses have a slot-like outer shape and are inserted with a depth of up to 2.5mm, preferably with a depth from a range of about 3pm to 0.3mm, in the respective axial surface. In other embodiments, the depth T of the recesses may also be chosen differently. The length of the depressions 54, that is to say their extent in the circumferential direction on the bobbin case carrier 12, can vary widely. So very small lengths, for example, from 0.5mm, up to a completely circumferential recesses on the bridge are possible. The length of the recesses is preferably selected from a range of about 0.8mm mm to about 4mm. The width of the individual depressions can be selected from 0.01 mm to almost the respective complete width of the web. The width is preferably selected from a range of 0.2mm to 1mm. In addition, for the wells in terms of their length and width any geometric shape is possible, even with dimensions below or above the above information. Notwithstanding the representations of FIGS. 10 to 12, circular shapes of the depressions are conceivable, for example. The depressions may also be provided instead of in the axial surfaces or in addition to depressions in at least one of the axial surfaces in the peripheral surface of the web 25.

In a preferred manufacturing method, the recesses 54 can be generated by the action of a laser beam in the respective surfaces 51, 52, 53 of the web 25. Suitable lasers for this purpose, with which such material removal on components made of steel, such as the bobbin case carrier 12, can be made, for example, fiber lasers with a power of about 20 W, as they are from Company IPG Photonics Corporation. Alternatively, the wells can also be made by milling.

As can be seen in the plan view of Fig. 4 and in the sectional view of Fig. 5, the gripper body 14 has two recesses 29, 30, which are formed as through holes 29, 30. The diameters of the two through holes 29, 30 may advantageously be from a range of 1 mm to 3 mm, preferably 1, 5 mm to 2.5 mm. In the embodiment, the diameter is 2mm. The through holes occur in the region of the boundary wall 19 of the receptacle 26 from the base 23. The two through holes 29, 30 open out of the gripper body 14 on the underside of the gripper body 14 in the region of an undercut 31 of the lower base surface 33. At least the through-hole 29 may be inclined with respect to the orientation of the axis of rotation of the drive shaft 16 and the orientation of the central through-hole.

As can be seen in FIG. 5, a wick 32, which protrudes from the upper opening of the second through-bore 30, is arranged in the second bore. The wick is here folded in the direction of the boundary wall 19 of the receptacle 26 and applied to the base 23.

The lower base surface 33 and the undercut 31 of the gripper body 14 result in a lower receptacle 36, in which a felt 35 in the region of the undercut 31 and the lower openings of the through holes 29, 30 is arranged.

The felt 35 belongs to an oil supply device, with which the felt 35 is supplied with machine oil as a lubricant. The felt 35 is thereby impregnated with machine oil. The lower end of the wick protrudes into the region of the undercut 31, which fills with oil during a rotation of the gripper body and the felt due to the centrifugal force from the felt. The wick 32 may receive at its lower end oil that rises due to capillary forces in the wick. As a wick comes, for example, a cotton round wick according to DIN 61300 in question. Instead of a felt may in other embodiments, a suitable Foam can be provided, which is able to absorb liquid lubricant and release again.

8 and 9, the oil supply device of the sewing machine is shown, as far as it is responsible for the oil supply of the gripper device 8. Accordingly, the felt 35 is arranged with its lower end in a recess 38 of a Ölleitbuchse 39, through which the drive shaft 16 is performed for the gripper body 14. The Ölleitbuchse 39 is mounted on a support surface of a fixed to the machine housing shown in Fig. 7 gripper jaw 40 for the gripper device 8. Laterally on the outside of the Ölleitbuchse 39, a connecting piece 42 is provided to which a supply hose 43 is connected. From the connector 42 from an unspecified inner channel of Ölleitbuchse 39 leads to several openings in the boundary wall of the recess 38 of the Ölleitbuchse 39. From here passes, the oil in the felt 35, which is capable of a certain amount of oil take.

With its other end, the supply hose 43 is arranged on a throttle 44 and a valve 45, from which in turn lead further supply hoses 46, 47 to a reservoir 48 for lubricating oil and a pump 49. By means of the pump 49 oil is pumped from the reservoir 48 into the Ölleitbuchse 39. With the valve 45, the amount of oil to be pumped to the felt 35 can be controlled.

For lubrication of the hook track 27 and the web 25, the oil pump 49 delivers oil from the reservoir 48 through the supply hoses 43, 46, 47 and the valve 45 for Ölleitbuchse 39. From here the oil passes through the openings of the Ölleitbuchse 39 for felt 35th Das lower end of the arranged in the region of the felt 35 wick 32 receives from the undercut 31 oil. As shown in Fig. 5, the oil is transported substantially by capillary forces in the wick 32 from the felt 35 and the undercut 31 through the second through hole 30 through to the upper receptacle of the gripper body 14. Due to the rotation of the gripper body, the oil emerging into the receptacle experiences a centrifugal force, due to which the oil moves from the top end of the wick towards the gripper track 27 in the effective direction of the centrifugal force. As it turned out, the hereby given Lubricant quantity at low speeds, in particular in the range of about 300 U / min to about 1000 U / min, suffice as the sole amount of lubricant.

Further lubrication of the hook race 27 and the web 25, which in particular starts at higher rotational speeds of the gripper body and comes about on the basis of another Förderwirkprinzips for the lubricant, takes place through the first through hole 29. The rotation of the gripper body 14 about the axis of the drive shaft 16 leaves the lubricant due to the centrifugal force or centrifugal force ascend in the through hole 29 free of other means in the through hole 29 upwards. The movement of the exiting from the through hole 29 oil is then as well as in the supply of lubricant through the wick due to the centrifugal force from the outlet opening of the through hole to the hook path. Since the flow rate of the oil through the through hole 29 is dependent on the rotational speed of the gripper body 14, larger flow rates of oil through the through hole 29 are promoted especially at higher speeds. Since at higher speeds there is also an increased need for lubricants, the two types of supply of lubricant based on different principles of action complement one another in the gripper body in an advantageous manner.

Over the entire speed range, oil thus enters the gripper track 27 as well as the surfaces 51, 52, 53 of the web 25. By means of the oil, the friction-related wear of said guide means of the gripper body 14 and the bobbin case carrier 12 is reduced. The recesses 54 in this case support that the axial surfaces 51, 52 of the web 25 wet well and evenly with oil and thereby forms a lubricant film between the friction surfaces of the guide means. LIST OF REFERENCE NUMBERS

Housing 31 undercut

Base plate 32 wick

Stand 33 base

Arm 34 boundary wall

Needle bar 35 felt

Arm shaft 36 recording

Gripper device 38 recess

Coil 39 oil guide

Spool capsule carrier 40 Gripper block

Outer surface 41 bearing surface

Gripper body 42 connecting piece centric through-bore 43 supply hose

Drive shaft 44 throttle

Transmission 45 valve

Needle guard 46 Supply hose

Boundary wall 47 Supply hose

Cover segment 48 reservoir

Screw 49 pump

Claw tip 51 upper axial surface

Base 52 lower axial surface

Bridge 53 Radial surface

Recording 54 recess

Groove (hook path)

Through Hole

Claims

claims

1. gripper device for arrangement in a sewing machine, which has a gripper body with a gripper tip, wherein the gripper body is provided to a rotating rotational arrangement about an axis of rotation in the sewing machine and a receptacle for the arrangement of a

Spulenkapselträgers in the gripper body, the bobbin case and the gripper body with guide means for mutual guidance

Rotational movements of the gripper body are provided, thereby

characterized in that at least one recess for receiving lubricant is provided on at least one surface of the guide means.

2. Gripper device according to claim 1, characterized by a plurality of wells.

3. gripper device according to one or both of the preceding claims, characterized in that the at least one recess is provided on a surface of the bobbin case carrier.

4. gripper device according to at least one of the preceding claims,

characterized in that the at least one recess are provided on a surface of a web formed as a guide means of the bobbin case.

5. Gripper device according to at least one of the preceding claims,

characterized in that the at least one recess are provided on at least one axial surface of the web.

6. Gripper device according to at least one of the preceding claims,

characterized in that the at least one recess on a

Circumferential surface of the web are arranged.

7. gripper device according to at least one of the preceding claims, characterized in that the at least one recess with respect to the surface in which it is introduced, a depth of up to 2.5mm, in particular from a range of 3μιη to 0.3mm ,

8. Gripper device according to at least one of the preceding claims 2 to 7, characterized in that a plurality of depressions are arranged one behind the other in at least one row.

9. gripper device according to at least one of the preceding claims,

characterized in that the at least one recess in a

Gripper track of the gripper body are provided.

10. Gripper device according to at least one of the preceding claims,

characterized in that the gripper body with a means for

Lubricant supply is provided for a lubrication, which allows the supply of lubricant in the region of the guide means.

1. Coil carrier for arrangement in a gripper of a sewing machine, which has a receptacle for a spool and which is provided with a web formed as a guide means for guiding in a gripper body, characterized in that on a surface of the web at least one recess for receiving lubricant, in particular a plurality of depressions is formed.