DE3838145C1 - - Google Patents

Abstract

A sealing masking band is to be welded onto a thread seam with turnings. The masking bond (A) is fed through a guide apparatus (18) which makes a U-shaped fold (F) in the centre of the masking band (A). During the welding process, an air stream is passed through the gap between the turnings (U) and the fold (F) which covers them, and prevents the masking band (A) and turnings (U) being welded together by keeping them apart. The process is intended for liquid-tight sealing of coated seat covers which are subsequently filled with expanded foam.

Description

The invention relates to a method and a Device for performing the method according to the respective preamble of claims 1 and 2.

In the manufacture of foam-padded seats becomes one-sided with thermoplastic Plastic coated fabric made by sewing Made seat cover with one inside the cover Expanded foam filled with the Coating of the fabric firmly connects. As a result of it can occur when foaming pressure pass through the foam when sewing created and not completely by the sewing threads filled in needle holes on the The outside of the fabric swells, causing the seats maintain unsightly appearance or even perfect become unusable.

To prevent this danger, it is known to be on the Thread seam, which is an edge seam with a protruding seam overhang weld on thermoplastic masking tape like it is proposed in principle by DE-PS 8 21 843. For this purpose, the masking tape becomes continuous fed, together with the coating of the fabric heated and with the help of pressure rollers on both sides the seam protrusion pressed, making it with the Coating firmly connects and the thread seam shields liquid-tight.  

For carrying out a continuously running Welding process, it is necessary that Masking tape always in the same alignment position Thread seam is welded. This requirement is not met if the masking tape is even in places one-sided with one of the two Side surfaces of the seam overhang is welded with. In this case, the masking tape inevitably migrates laterally out of the desired alignment position, see above that it initially covers the thread seam unevenly and after all, is no longer able to cover.

The invention has for its object a method and a device for connecting a surface Masking tape according to the preamble of claim 1 or 2 to create, which ensures that the Masking tape of any length in the same Alignment position can be applied to the thread seam to be covered is. The object is achieved by the im Characteristic part of claim 1 and 2 specified Features solved.

By the measure that is on both sides of the Seam overhang to be applied to an im essential U-shaped fold with the fabric layers to form parallel end portions and during of connecting or welding within the Space between the seam overhang and the fold Allowing an air poster to act will do that Seam protrusion with covering tape covering the distance Connection or welding point stabilized fed and in the area of connection or Weld from the two side surfaces and the Top of the seam protrusion kept away, whereby is prevented that the masking tape on the  Seam protrusion is present and neither overall nor in places with this is connected with. As a result of this occur on the masking tape during the Joining or welding no sideways pull or Ab steering forces on, so that it can be used even over long distances can be connected or welded free of distortion and folds.

Since the flowing through between the seam overhang and the masking tape and at the same time a compressed air that builds up an air cushion and a cooling system kung, in the event that the masking tape despite the compressed air Stromes should occasionally be on the seam protrusion changes that the point of contact when welding down to the weld temperature is heated. Thus, due to the cooling effect of the compressed air an additional guarantee that the masking tape is not on Seam overhang is welded.

In claims 2 to 4 is a first embodiment of a front direction specified for carrying out the method, being special Measures to guide and shape the masking tape and the fabric conditions have been met.

In claim 5, a second embodiment of the device is specified ben, in which by a fixed attachment of the heating element Possibility was created the exit ends of the guiding apparatus for the masking tape and the fabric layers particularly close to the pressure roller len, which is a prerequisite for welding narrow Radii is.

Since it is very important for achieving a uniform welding result it is important that the welding temp temperature is kept at a substantially constant value, should be the inevitable after switching on the welding device Abge heating phase of the heating element before the start of the welding process be closed. To avoid the associated loss of time, is left with welding equipment equipped with a hot air device  the hot air device is switched on during the welding breaks, the Hot air during this time usually by swiveling the Hot air nozzle is kept away from the welding point. At one place fixed hot air nozzle can be hot air according to claim 6 Keep away from the welding point by moving the hot air device is arranged bar and with a deflection flap for the hot air flow cooperates.

The invention is based on two in the drawing  illustrated embodiments explained. It demonstrate:

Figure 1 is a diagrammatic representation of a part of a welding machine, each with a guide device for the masking tape and the layers of fabric.

Figure 2 is a sectional view through the guide apparatus.

Figure 3 is a sectional view through two means of a thread stitching interconnected fabric layers and a suture thread through the opaque cover.

Fig. 4 is a perspective view of the second embodiment of a welding machine, wherein the hot air nozzle designed as heater element is stationary;

Fig. 5 is a perspective view of a diverter for the flow of hot air contained in the active position;

Fig. 6 is a diagrammatic representation of the deflection flap in the inactive position.

Embodiment 1

The housing of the welding machine, which is only shown in part, has a head ( 1 ), an arm ( 2 ) supporting it and a column ( 3 ) attached to a base plate (not shown).

Arranged on a support ( 4 ) attached to the head ( 1 ) is an upper pressure roller ( 5 ) which is spring-loaded in the vertical direction and is divided into two roller sections ( 7 , 8 ) by an annular groove ( 6 ). A lower pressure roller ( 9 ) is arranged on the column ( 3 ). Both pressure rollers ( 5 , 9 ) can be driven synchronously with each other by known drive devices, not shown.

A swivel bracket ( 11 ) for a hot air nozzle ( 12 ) is arranged on a support ( 10 ) attached to the head ( 1 ), said swivel bracket being located between a rest position remote from the pressure rollers ( 5 , 9 ) and a position close to the pressure rollers ( 5 , 9 ). lying working position is movable. The hot air nozzle ( 12 ) is fork-shaped and has two outlet openings ( 13 , 14 ), the width and mutual distance of which corresponds to the width and the mutual distance of the roller sections ( 7 , 8 ).

On the head ( 1 ) a carrier ( 15 ) for a supply roll ( 16 ) is attached, which contains a thermoplastic masking tape A. A guide ( 18 ) for the band A is arranged on a holder ( 17 ) attached to the head ( 1 ). The guide device ( 18 ) has a sheet metal sleeve ( 19 ) which contains a flat guide channel ( 20 ) ( Fig. 2) with an inlet opening ( 21 ) which extends in a straight line. The sheet metal sleeve ( 19 ) has an essentially U-shaped, upwardly directed bulge ( 22 ) which increases in size from the inlet opening ( 21 ) in the direction of the opposite outlet opening (not designated). The guide device ( 18 ) is directed obliquely downwards and runs essentially tangentially to the outer surface of the upper pressure roller ( 5 ), the bulge ( 22 ) being aligned with the annular groove ( 6 ).

The end section ( 23 ) of a compressed air line ( 24 ) is attached to the concave underside of the bulge ( 22 ) and is connected to a compressed air source, not shown. The outlet opening ( 25 ) of the compressed air line ( 24 ) lies essentially in the same plane as the outlet opening of the guide apparatus ( 18 ) and faces the welding point ( 26 ) located between the pressure rollers ( 5 , 9 ).

An essentially horizontal guide plate ( 28 ) is arranged on a holding rod ( 27 ) attached to the head ( 1 ), the central area of which is designed as an upward bulge ( 29 ). This bulge ( 29 ) tapering in the direction of the welding point ( 26 ) lies with the bulge ( 22 ) of the guide apparatus ( 18 ) in a common vertical plane and forms a guide channel ( 30 ).

A guide plate ( 32 ) is arranged on a bracket ( 31 ) which is adjustably fastened to the column ( 3 ), which runs at a flat angle to the guide plate ( 28 ) lying above it and together with this forms a guide apparatus ( 33 ). The central region of the lower guide plate ( 32 ) is curved upward, as a result of which a flat guide rib ( 34 ) which extends in the same direction and which increases towards the weld ( 26 ) is formed below the bulge ( 29 ) of the upper guide plate ( 28 ) becomes flatter and ends before the end edge of the guide plate ( 32 ).

It works as follows:

The seat cover ( H ) to be filled with foam in a later step has two layers of fabric ( S 1 , S 2 ) provided with a thermoplastic coating ( B ), which are connected to each other by a thread seam ( N ) in such a way that a seat cover that is spread out flat ( H ) after upstanding seam protrusion ( U ) is formed.

For the liquid-tight shielding of the thread seam ( N ), the thermoplastic masking tape ( A ) is welded over the seam protrusion ( U ) on both sides of the thread seam ( N ) onto the overlying coating ( B ). For this purpose, the seat cover ( H ) is first pushed into the gap between the guide plates ( 28 , 32 ) of the guide apparatus ( 33 ), the area of the thread seam ( N ) being straddled on the guide rib ( 34 ) and the seam protrusion ( U ) is inserted centrally into the guide trough ( 30 ). When pushing the layers of fabric ( S 1 , S 2 ) in the direction of the weld ( 26 ), they are brought into a flat position in the area of the thread seam ( N ) due to the flattening guide rib ( 34 ).

If the cover band ( A ) is not already received in the guide apparatus ( 18 ), the end of the band is now inserted into the guide channel ( 20 ) of the sheet metal sleeve ( 19 ) and pushed through to its outlet opening. The cover tape ( A ) is formed into a U-shaped fold ( F ) with two end regions ( E 1 , E 2 ) oriented parallel to the fabric layers ( S 1 , S 2 ).

Before the welding machine is switched on, the compressed air line ( 24 ) is pressurized with compressed air, whereupon a continuous air flow emerges from the end section ( 23 ) and flows below the apex region of the fold ( F ) in the direction of the welding point ( 26 ). Due to the air flow, the fold ( F ) is dimensionally stabilized after the cover band ( A ) emerges from the guide apparatus ( 18 ), which prevents the fold ( F ) from narrowing or tipping sideways. After the masking tape ( A ) has reached the layers of fabric ( S 1 , S 2 ), the compressed air flows through the space ( Z ) between the fold ( F ) and the seam overhang ( U ) and creates an overpressure within the space ( Z ) that has the effect of an air cushion. In this way it is achieved that the fold ( F ) to the side surfaces and the top of the seam overhang ( U ) maintains a uniform distance.

As soon as the layers of material ( S 1 , S 2 ) and the masking tape ( A ) are in the starting position required for carrying out a welding process, the hot air nozzle ( 12 ) is pivoted into its working position and the welding machine is switched on. During the beginning of the welding process, the end areas ( E 1 , E 2 ) of the masking tape ( A ) lying flat on the coating ( B ) of the fabric layers ( S 1 , S 2 ) are heated to the welding temperature together with the corresponding sections of the coating ( B ) and pressed together by the subsequent pressure rollers ( 5 , 9 ) and welded together. The gap between the U-shaped fold ( F ) and the seam protrusion ( U ), which at the same time creates a cooling effect, reliably prevents the fold ( F ) from being welded to the seam protrusion ( U ).

Embodiment 2

The welding machine of this exemplary embodiment essentially corresponds to that of the first exemplary embodiment, ie the structure of the housing, the arrangement of the pressure rollers ( 5 and 9 ) and the design of the guide device ( 18 ) for the cover tape ( A ) and the guide device ( 33 ) for the fabric layers ( S 1 , S 2 ) are identical.

However, there is a difference in the arrangement of the two guiding devices ( 18 , 33 ). In the second exemplary embodiment according to FIG. 4, they are arranged at a flatter common angle, as a result of which their outlet ends ( 40 , 41 ) can be brought much closer to the welding point ( 26 ) located between the pressure rollers ( 5 , 9 ).

In this case, since the distance between the guiding devices ( 18 , 33 ) is so narrow that a movably arranged hot air nozzle could no longer be inserted into the welding position, or only with great difficulty, a permanently installed hot air nozzle ( 42 ) is provided in this exemplary embodiment which, however, is, like the hot air nozzle ( 12 ) of the first embodiment, fork-shaped.

The hot air nozzle ( 42 ) is fastened to one end of a tube ( 43 ) which is held by a support ( 44 ) arranged on the arm ( 2 ). At the other end of the tube ( 43 ) a funnel-like mouthpiece ( 45 ) is attached. A plate-shaped slide ( 47 ) is arranged on two guide rods ( 46 ) of the carrier ( 44 ) and is connected to the piston rod ( 48 ) of a compressed air cylinder ( 49 ). A hot air device ( 50 ) is attached to the slide ( 47 ) and has a cylindrical nozzle ( 51 ).

As can be seen from FIGS. 5 and 6, a permanently installed exhaust air duct ( 52 ) is provided, the rectangular inlet opening of which is designated by ( 53 ). A deflection flap ( 54 ) is assigned to the exhaust air duct ( 52 ) and is arranged on a vertically running, stationary shaft ( 55 ). The deflection flap ( 54 ) is designed as a hollow body open on two sides with an arcuate guide surface ( 56 ). A partially projecting stop plate ( 57 ) is attached to the deflection flap ( 54 ).

A tension spring ( 58 ), which exerts a torque on the shaft ( 55 ) via a lever ( 59 ), causes the deflection flap ( 54 ) when the hot air device ( 50 ) is retracted according to FIG. 5 with the stop plate ( 57 ) on the exhaust air duct ( 52 ) abuts, the outlet side ( 60 ) of the deflection flap ( 54 ) being aligned with the inlet opening ( 53 ) of the exhaust air duct ( 52 ).

Functionality:
The hot air device ( 50 ) is switched on continuously and therefore also generates hot air during the breaks between the processing of two successive seat covers. During the processing breaks, the hot air device ( 50 ) is in the retracted position shown in FIG. 5, in which the nozzle ( 51 ) partially projects into the deflection flap ( 54 ). The hot air flowing out of the nozzle ( 51 ) hits the arcuate guide surface ( 56 ) and is deflected by this in the direction of the exhaust air duct ( 52 ).

As soon as a seat cover to be reworked is in the working position, ie the beginning end of a seam to be covered is inserted into the guide device ( 33 ), the hot air device ( 50 ) is pushed into the working position according to FIG. 6 with the aid of the compressed air cylinder ( 49 ). During this movement, the nozzle ( 51 ) abuts the inside of the deflection flap ( 54 ) and pivots it into the inactive position shown in FIG. 6. The displacement movement of the hot air device ( 50 ) ends as soon as the nozzle ( 51 ) touches the mouthpiece ( 45 ) which acts as a stop. In this position, the nozzle ( 51 ) and the mouthpiece ( 45 ) form a coupling between the hot air device ( 50 ) and the hot air nozzle ( 42 ).

After a delay time serving to heat the tube ( 43 ) and the hot air nozzle ( 42 ), the drive of the pressure rollers ( 5 , 9 ) is switched on and a new welding process is initiated. This welding process proceeds in the same way as described in embodiment 1 .

Claims (6)

1. Method for areal - for example by welding or gluing - connecting a masking tape with fabric layers to ver at the sides of the seam protrusion one of the fabric layers binding together, formed as a thread seam, characterized in that the masking tape ( A ) in front of the connection point the substantially U-shaped fold ( F ) is formed into a seam overhang ( U ) to form an intermediate space ( Z ) with end regions ( E 1 , E 2 ) oriented essentially parallel to the fabric layers ( S 1 , S 2 ) and that during the connection of the end regions ( E 1 , E 2 ) of the cover tape ( A ) with the fabric layers ( S 1 , S 2 ) in the intermediate space ( Z ) a cover tape ( A ) from the seam overhang ( U ) separating air cushion is generated . 2. Device for carrying out the method according to claim 1, in which the connection of the masking tape to the layers of material is carried out by welding, with a heating element and two downstream pressure rollers, characterized in that a guide device ( 18 ) for above the heating element ( 12 ; 42 ) the cover band ( A ) and below the heating element ( 12 ; 42 ) a guide device ( 33 ) for the layers of fabric ( S 1 , S 2 ) is arranged, the guide device ( 18 ) for the cover band ( A ) being supported by a flat sleeve ( 19 ) is formed which, starting from the inlet opening ( 21 ) in the direction of the outlet opening, has an increasingly larger, substantially U-shaped bulge ( 22 ) and that beneath the bulge ( 22 ) a substantially parallel to the longitudinal direction of the sleeve ( 19 ) extending end section ( 23 ) of a compressed air line ( 24 ) is arranged, the outlet opening ( 25 ) facing the pressure rollers ( 5 , 9 ). 3. Apparatus according to claim 2, characterized in that the guide apparatus ( 33 ) for the layers of material ( S 1 , S 2 ) consists of two guide plates ( 28 , 32 ) tapering at a flat angle, one of which is the upper guide plate ( 28 ) has the seam protrusion ( U ) laterally supporting guide trough ( 30 ). 4. The device according to claim 3, characterized in that the lower guide plate ( 32 ) of the guide apparatus ( 33 ) has an upwardly directed guide rib ( 34 ). 5. The device according to one or more of claims 2 to 4, characterized in that the guide apparatus ( 18 , 33 ) to achieve a particularly short distance between their outlet ends ( 40 , 41 ) and the pressure rollers ( 5 , 9 ) at a flat angle are aligned with each other and that the heating element ( 42 ) is arranged in a fixed position at a short distance from the pressure rollers ( 5 , 9 ). 6. The device according to claim 5, wherein the heating element is formed by a hot air nozzle connected to a hot air device, characterized in that the hot air device ( 50 ) between a with a mouthpiece ( 45 ) engaging work and a distant rest position movable back and forth and that the outlet opening (nozzle 51 ) of the hot air device in the rest position is shielded by a deflection flap ( 54 ) which in this position is aligned with the inlet opening ( 53 ) of an exhaust air duct ( 52 ) and through the hot air device ( 50 ) when moving into the Working position can be swung away into an ineffective position.