Technical Field

The present invention relates to a rotary dyeing head for edges of leather pieces and finished leather articles, which is used in the haberdashery-leather industry.

Background of the Invention

One of the basic process steps in the haberdashery-leather industry is the step of dyeing edges of leather pieces and finished leather articles. Substantially, this step includes application of water-soluble dye, whereas the quality of the process step executed depends on the amount of dye deposited on the edge of the piece or finished article to be dyed.

WO 2018/129597 A1 discloses an apparatus for dyeing edges of leather pieces comprising a vertically arranged dyeing head connected to a motor via a magnetic coupling. The dyeing head comprises a dyeing shaft and an eccentric pump connected to a dye container, said dyeing shaft and said eccentric pump having a common rotation axis and connected to each other by means of a channel-and-tube system. The dyeing shaft is provided with a plate for controlling the thickness of the dye film on said dyeing shaft, the plate being arranged perpendicularly to the shaft axis and tangentially to the lateral surface thereof. The magnetic coupling consists of magnets for the dyeing shaft arranged radially and incorporated into a magnet holder which is attached to the dyeing shaft axis, and magnets for the motor also being arranged radially and incorporated into a second magnet holder attached to the motor axis, whereby both holders have an equal number of magnets arranged one above the other. In the dyeing process, the edge of the piece is touched the dyeing shaft which transfers dye onto the piece. In this known apparatus, the dyeing shaft diameter is significantly smaller which ensures the transfer of a greater amount of dye onto the leather piece per one application and, as a result of this, the number of applications of dye onto the piece reduces which leads to significant reduction of the duration of the whole process. On the other hand, the area on which the dye is applied is on the side of the dyeing shaft and the operator has difficulty monitoring the dyeing result. The operator checks how the piece has been dyed after completing the whole operation, which creates difficulties for the immediate control of the quality of the operation executed. In addition, sometimes this allows for formation of edging both on the front part and on the rear part of the piece. The eccentric pump used in the apparatus construction is a relatively complex mechanism requiring additional modules, such as a system of channels for dye transference from the dye container to the dyeing shaft, which further complicates the design of this known apparatus.

DE 295 18 563 U1 discloses a device for dyeing edges of leather pieces comprising a dyeing roller having a vertically arranged axis and driven by a motor via a coupling. The dyeing roller is arranged in the upper part of a hollow cylinder, in which lower part, a delivery screw pump is located. The hollow cylinder with the delivery screw pump are immersed in a dye container. In the upper part of the hollow cylinder, an opening is formed for discharging the dye sucked-in by the screw pump from the dye container and for transferring the dye onto the dyeing roller. In this known device for dyeing leather pieces, the area on which the dye is applied is on the side of the dyeing shaft and the operator has difficulty monitoring the dyeing result. Furthermore, finished articles are very difficult to dye using this device, due to the fact that the dyeing roller is located in the middle of the device having a complex design, and the access to the dyeing area is highly restricted.

Disclosure of the Invention

An object of the present invention is to provide a rotary dyeing head for leather pieces and finished leather articles having a simplified design and allowing for operation in a vertical, inclined and horizontal position of the dyeing shaft.

Another object of the present invention is to provide a rotary dyeing head which is able to prevent formation of edging on the front and rear parts of the piece to be dyed.

A further object of the present invention is to provide a rotary dyeing head which can be easily and quickly cleaned from the dye.

The present invention provides a rotary dyeing head for dyeing edges of leather pieces and finished leather articles, the rotary dyeing head including a delivery screw pump, a dyeing means, a dye container and an adjusting plate for adjusting the thickness of dye layer on the dyeing means. According to the present invention, the rotary dyeing head comprising said delivery screw pump, a guide sleeve bearing, a suction screw pump and said dyeing means representing a dyeing shaft arranged sequentially and coaxially. The delivery screw pump, the guide sleeve bearing and the suction screw pump are enclosed by an external pipe that is immersed in said dye container closed with a protecting cap. Suction openings are formed in the base of the delivery screw pump, and the guide sleeve bearing with radial openings are provided, said radial openings are in communication with a central channel formed along a common axis of the guide sleeve bearing, the suction screw pump and the dyeing shaft, at the end of which an outlet for outflow the dye to the outer dyeing surface of said dyeing shaft is formed. In the external pipe, an opening is formed for returning the excess dye from the outer dyeing surface of the dyeing shaft to said dye container by means of said suction screw pump. A magnet holder having magnets incorporated therein is mounted at the base of said delivery screw pump, said magnet holder being a part of a magnetic coupling connecting said delivery screw pump (6) to a stepper motor by means of a second magnet holder of said magnetic coupling. The rotary dying head is provided with a mechanism for rotating and locking the rotary dyeing head from a vertical to horizontal position - at 86 degrees in relation to the dyeing shaft being in a vertical position.

In one embodiment of the present invention, said adjusting plate is connected, by means of an axis, to a handle for adjusting the clearance between the dyeing shaft and the adjusting plate, which is secured to the protecting cap of the dye container.

In one preferred embodiment of the invention, the mechanism for rotating and locking the rotary dyeing head from a vertical to horizontal position comprises a U-shaped plate rigidly fixed to a rotary dyeing head housing, and a movable support plate attached to the bottom of the dye container, whereby the U-shaped plate and the movable support plate are fastened to each other by means of a threaded axis, at both ends of which locking handles (20) for rotating and fixing a working angle selected for the rotary dyeing head are mounted, wherein the second magnet holder of the magnetic coupling is attached to the movable support plate, and a wire, which is a soft connection to the stepper motor, is mounted to said second magnet holder for transmitting the rotation from the stepper motor to the delivery screw pump by means of the magnetic coupling. Thus, the rotary dyeing head is capable of rotating about the threaded axis, together with the second magnet holder and the wire mounted thereto.

The advantages of the rotary dyeing head according to the present invention are as follows:

- The rotary dyeing head has a simplified design, which ensures significantly easier maintenance by the operator due to the small number of components and the high reliability during operation.

- The rotary dyeing head allows for dyeing leather pieces in any position of the dyeing shaft - from a vertical to horizontal position, providing direct monitoring of the dyeing process, which increases the quality of the applied layer of dye. Both pieces and finished articles may be dyed, without restrictions as regards the size and shape thereof, and also, all types of leather pieces are allowed to be dyed - both of soft leather and hard leather. The operator is able to adjust the dyeing head at an angle, so that the detail to be dyed may remain in a vertical or horizontal position, and the surface on which the dye is applied may be perpendicular to the dyeing shaft axis.

- The rotary dyeing head is able to prevent formation of edging on the front and rear parts of the piece to be dyed.

- The rotary dyeing head can be easily and quickly cleaned from the dye due to its simplified design.

Brief Description of Drawings

FIG. 1 is a schematic diagram of a rotary dyeing head in a vertical position;

FIG. 2 is a schematic diagram of a rotary dyeing head in an inclined position;

FIG. 3 is a schematic diagram of a rotary dyeing head in a horizontal position;

FIG. 4 is a front view of a rotary dyeing head in a vertical position;

FIG. 5 is an axonometric view of a rotary dyeing head;

FIG. 6 is an axonometric view of a rotary dyeing head from another side;

FIG. 7 is an axonometric view of a rotary dyeing head in a vertical, inclined and horizontal position illustrating the principle of transferring the dye from the dyeing shaft onto a leather piece.

Modes for Carrying Out the Invention

FIG. 1 - FIG. 6 illustrate a rotary dyeing head according to the present invention comprising a delivery screw pump 6, a guide sleeve bearing 11, a suction screw pump 10 and a dyeing shaft 5 arranged sequentially and coaxially and being a single detail. The delivery screw pump 6, the guide sleeve bearing 11 and the suction screw pump 10 are enclosed by an external pipe 16 that is immersed in a dye container 1 being closed with a protecting cap 2. Suction openings 15 are formed in the base of the delivery screw pump 6, and the guide sleeve bearing 11 with radial openings 13 are provided, said radial openings 13 are in communication with a central channel 9 formed along a common axis of the guide sleeve bearing 11, the suction screw pump 10 and the dyeing shaft 5 for discharging the dye from the increased pressure area of the delivery screw pump 6 to the end of the dyeing shaft 5. At the end of the central channel 9, an opening 24 for outflow the dye to the outer dyeing surface of said dyeing shaft 5 is formed.

An adjusting plate 4 is provided for adjusting the thickness of a layer of dye on the outer dyeing surface of the dyeing shaft 5, said adjusting plate 4 is connected, using an axis (not shown), to a handle 3 for adjusting the clearance between the dyeing shaft 5 and the adjusting plate 4 which is attached to the protecting cap 2. In an external pipe 16, an opening 12 is formed for returning the excess dye from the outer dyeing surface of the dyeing shaft 5 into the dye container 1 by means of the suction screw pump 10.

A magnet holder 7 having magnets and an axial bearing 8 incorporated therein are mounted at the base of the delivery screw pump 6, said magnet holder 7 being a part of a magnetic coupling 25 connecting the delivery screw pump 6 to a stepper motor (not shown) using a second magnet holder 22 of the magnetic coupling 25 (see FIG. 2, FIG. 3).

A mechanism 21 for rotating and locking the dyeing head from a vertical to horizontal position - at 86 degrees in relation to the dyeing shaft 5 being in a vertical position - is provided. FIG. 1 shows the dyeing head in a vertical position, FIG. 2 - in an inclined position, and FIG. 3 - in a horizontal position. In this embodiment, a mechanism 21 for rotating and locking the rotary dyeing head in selected position comprises a U- shaped plate 14 (FIG. 2, FIG. 3) rigidly fixed to the rotary dyeing head housing (not shown), and a movable support plate 17 attached to the bottom of the dye container 1, whereby the U-shaped plate 14 and the movable support plate 17 are fastened to each other by means of a threaded axis 19 at both ends of which locking handles 20 for rotating and fixing the working angle selected for the rotary dyeing head are mounted. Said second magnet holder 22 which is the outer part of the magnetic coupling 25 is attached to the movable support plate 17, and a wire 18, which is a soft connection to the stepper motor, is mounted thereon for transmitting the rotation from the stepper motor to the delivery screw pump 6 by means of the magnetic coupling 25. The rotary dyeing head is capable of rotating about the threaded axis 19, together with the second magnet holder 22 of the magnetic coupling 25 and the wire 18 attached thereto.

The rotary dyeing head for leather pieces and finished leather articles operates, as follows:

Rotation is transmitted from the stepper motor to the delivery screw pump 6 through the wire 18 and the magnetic coupling 25, and as a result the dye is sucked-in from the container 1 via the suction openings 15 and is delivered towards the guide sleeve bearing 11 that does not allow the dye delivered to pass towards the suction pump 10 due to the small clearance between the guide sleeve bearing 11 and the external pipe 16. The dye delivered is passed through the radial openings 13, entered the central channel 9 passing therethrough, whereupon the dye is discharged through the outlet 24 and poured on the outer surface of the dyeing shaft 5.

Adjustment of a layer of dye on the dyeing shaft 5 is executed by means of the adjusting plate 4, whereby when the adjusting plate 4 is approached the dyeing shaft 5, the layer of dye on the dyeing shaft 5 is reduced, and when the adjusting plate 4 is moved away from the dyeing shaft 5, the layer is increased. Adjustment of the clearance between the adjusting plate 4 and the dyeing shaft 5 is executed by rotating the handle 3. The excess dye is run down the adjusting plate 4 and is reached the inlet of the suction screw pump 10, which is delivered the excess dye into the dye container 1 through the opening 12.

The rotary dyeing head is able to operate with the dyeing shaft 5 being in a vertical position (FIG. 1), in an inclined position at a desired angle (FIG. 2) and in a horizontal position (86 degrees relative to the horizontal - FIG. 3), i.e. at an angle of 90° to 4° relative to the horizontal. To adjust the inclination angle of the dyeing head, the locking handles 20 are moved away, U-shaped plate 14 and movable support plate 17 are disengaged from each other and the movable support plate 17 is rotated about the threaded axis 19 thereof. Fixing in the position selected is executed by tightening the locking handles 20.

FIG. 7 shows the position and the direction of movement of a leather piece 23 in relation to the dyeing shaft 5 that is in a vertical position, inclined position at two different angles and horizontal position during the process of dyeing using the rotary dyeing head according to the invention. As seen from this figure, the operator is able to monitor the process of dyeing and the dyeing result.

In cases where the surface to be dyed is not perpendicular to the plane of the piece, when using known vertical or horizontal dyeing head, the operator holds the surface to be dyed at a precisely determined angle relative to the dyeing shaft so that the plane on which the dye will be applied is perpendicular relative to said dyeing shaft. This is difficult and, in practice, leads to poor dyeing quality. Using the rotary dyeing head according to the present invention, the operator is able to adjust the angle of the rotary dyeing head to an angle complementing to 90 degrees the angle under which dyeing will be executed relative to the horizontal, and thus, the piece, during dyeing, may remain in a vertical or horizontal position, and the surface on which the dye will be applied may be perpendicular to the axis of the dyeing shaft. In this case, it will be of no importance for the operator whether he will dye a piece having a perpendicular plane of dyeing relative to the piece or a piece having a plane of dyeing which does not form an angle of 90 degrees relative to the piece plane.

Another essential advantage of the rotary dyeing head according to the present invention is the capability of dyeing large finished articles. In case of known vertical or horizontal heads, it is in practice very difficult to dye articles of this type since the dye container is located under the dyeing shaft, at a small distance therefrom, and when dyeing large finished articles, they touch said dye container and obstruct the dyeing process. This problem is solved with the rotary dyeing head according to the present invention, whereby the operator can rotate the dyeing head to a horizontal position using the rotating mechanism 21, and since in a horizontal position the dyeing shaft is arranged eccentrically relative to the dye container 1, and the dyeing shaft is almost in-line with the dye container 1. In this way, the space under the dyeing head is completely free and the finished articles to be dyed are able to be positioned under the rotary head. The rotary dyeing head according to the present invention provides very good possibilities for dyeing any type of finished articles, compared to the other known types of dyeing heads.