EP1151811B1 - Method and apparatus for making a hollow cylinder with curved bulged structure - Google Patents

Abstract

To produce a hollow honeycomb cylinder it is forced by a press roller (28,29) against supports on a die (15) and rotated, against the roller rotation. The supports form the outer surface of a cylinder segment, with a radius matching the radius of the hollow cylinder (100). During the rotation, the honeycomb structure is embossed without slipping at its inner wall.

Description

The invention relates to a method and an apparatus for producing a vault-structured hollow cylinder, in particular a jacket for the drum or the tub of a washing machine, in which this pressed by a pressure roller against support elements and opposite to a rotational movement of the pressure roller is set in rotation.

From WO 97/35705 A1 a method for buckling of thin webs of material is known. In this case, the support elements are arranged on a first roller, against which a pressure roller is pressed with the interposition of the material web. In one embodiment, the structuring of a hollow cylinder will be described. The pressure roller is provided in this embodiment with a flexible surface. The rotation of at least one of the two rollers and / or the hollow cylinder creates an opposite rotation, in which the material web is pushed between the two rollers. In doing so, self-organization creates defilements. Since the roller carrying the support elements has a smaller radius than the hollow cylinder, hollow cylinder and roller rotate at different rotational speed and there is a relative movement between these two parts. The hollow cylinder is therefore held in its contact area only by the pressure of the two rollers. As a result, the cylinder wall can wobble horizontally and vertically and a slip between the wall and the support elements arise. In order to obtain uniform structures, the roller with the support elements must also be repositioned after each structuring process. Another disadvantage results from markings that arise due to the free movement of the hollow cylinder on the support elements.

From US 4,487,048 a method for deforming hollow cylinders is known in which the hollow cylinder is rotated in opposite directions relative to a rotating roller acting as an external tool. The rotating roller includes projections which are impressed into the hollow cylinder as a structure, wherein the roller is made under pressure on the hollow cylinder and guided circumferentially on its circumference. Since the roller rolls with the einzubrägenden structure on the hollow cylinder, a slip between the roller and the hollow cylinder can not be excluded.

From WO 98/20195 A1 it is generally known to provide the jacket of a washing machine drum according to the method described above with a bulge or vault structure in the form of polygons and to arrange holes in the vertices of these polygons. The slippage during structuring produces irregular patterns, resulting in an arrangement of the Holes in the corners difficult. This is especially the case if the perforation is to take place before structuring.

The invention thus raises the problem of disclosing a method and an apparatus for producing a vault-structured hollow cylinder of the type mentioned, which ensures regular Völbstrukturen on the hollow cylinder.

According to the invention, this problem is solved by a method having the features of patent claim 1 and by a device having the features of claim 4.

Advantageous embodiments and further developments emerge from the respective following subclaims.

The achievable with the present invention consist in the regularity of the applied to the hollow cylinder arch structures, which results from the fact that the support elements bear against the entire surface of the inner wall of the cylinder and no slip between support elements and sheet occurs. Another advantage is that no embossing marks are produced at the edges of the structures.

In an advantageous embodiment of the method according to the invention three carriers are used and each carrier is associated with a pressure roller, wherein the pressure rollers are each offset by 120 ° and at the same time pressed against the hollow cylinder. As a result, the transverse forces on the hollow cylinder cancel and there is a high process reliability.

In a method for producing a vault-structured drum shell of a washing machine drum, it is advantageous if the drum shell is rotated by about 100 ° with the adjoining support elements for applying the arch structure. This leaves three sub-segments of the drum shell unstructured. In these areas scoop ribs can be used.

Figur 1a

einen Längsschnitt durch eine Vorrichtung zur Herstellung eines wöfbstrukturierten Trommelmantels (100) einer Waschmaschinentrommel;

Figur 1b

einen Horizontalschnitt durch die Vorrichtung gemäß Figur 1;

Figur 2

einen Längsschnitt durch das Innenteil einer Vorrichtung gemäß Figur 1a und b;

Figur 3

eine Matrize einer Vorrichtung gemäß Figur 1 u. 2 als Einzelheit in perspektivischer Darstellung.

An embodiment of the invention is shown purely schematically in the drawings and will be described in more detail below. It shows

FIG. 1a

a longitudinal section through an apparatus for producing a roll-structured drum shell (100) of a washing machine drum;

FIG. 1b

a horizontal section through the device of Figure 1;

FIG. 2

a longitudinal section through the inner part of a device according to Figure 1a and b;

FIG. 3

a die of a device according to Figure 1 u. 2 as a detail in perspective view.

The apparatus shown in Figures 1a and b is on a table-shaped base frame, consisting of a base plate (1) and three feet (2) constructed. In a central opening (7) of the base plate (1) has a bearing housing (3) is inserted, which carries a rotatable inner part. The inner part shown in Figure 2 includes a bearing sleeve (4) which carries at its lower end a gear (5) and at its upper end a turntable (6) on which an inner tool is arranged. In addition, an outer opening (8) in the base plate (1) receives a three-phase motor (9) which drives a gear (10) in the area under the plate (1). The gears (5) and (10) are coupled by a toothed belt (11). As a result, the turntable (6) can be driven with a force of 2500 Nm. The interior tool consists of three expanding jaws (12) which are guided on the turntable (6) displaceable in the radial direction, wherein the guides are each offset by 120 °.

The expansion jaws (12) shown in Figure 2 have the shape of cylinder segments which form an angle of about 100 ° with the central axis. These are cut obliquely from the outer region of the upper cover surface to the inner region of the lower cover surface, so that a cut surface is formed which is inclined in such a way that its distance from the central axis of the cylinder tapers downwards. In this way, the expanding jaws (12) form on the outside of a cylinder with vertical columns and in the interior creates an opening in the form of an upside-down truncated pyramid. To secure against movement in the axial direction, a retaining ring (13) is placed on the segments and connected to the turntable (6) via stud bolts (14). The studs extend through the vertical column.

The spreading jaws (12) act as supports for matrices (15) shown in FIG. 3, on which honeycomb-shaped support elements (15a) for generating a bulge structure in the form of nested hexagons are arranged.

Through the bearing sleeve (4) extends a tie rod (16) which carries at its upper end a truncated pyramid widening wedge (17). At its lower end, the pull rod (16) in the center of a crossmember (18) is rotatably mounted. The traverse is coupled at its ends via two hydraulic cylinders (19) with the base plate (1) and can thus move the tie rod (16) in the axial direction. Additional guides (20) prevent tilting of the drawbar (16). To ensure that when raising the wedge (17), the expanding jaws (12) are moved back to its inner starting position (12 '), the surfaces of the expanding wedge with sliding blocks (21) are provided in guides (22) in the cut surfaces of Spread spreader jaws (12).

A receiving ring (23) for centering the drum shell (100) surrounds the turntable (6) concentrically and is connected via three pneumatic cylinders (24) with the top of the base plate (1). It has a bevelled centering edge (23a). In addition, a bolt (25) is arranged on it, which (not shown) via a further pneumatic cylinder in the radial direction of the drum shell (100) can be moved. The height of the retainer ring is adjustable to accommodate drum shells (100) with different depths.

In three vertices are arranged on the top of the base plate (1) each offset by 120 ° fixed brackets (26). The brackets each carry a holder (27) in the form of a C-bracket, in which a steel roller (28) is rotatably inserted about a vertical axis. These wheels are coated with Eladur (29), a polyester-based polyurethane elastomer with a hardness of about 90 Shore A. The brackets (27) via hydraulic cylinders (30) in the radial direction of the drum shell (100) to a stop (31) movable, the travel and thus the pressing force of the rollers (28) be adjusted via a stroke adjustment (32).

The following describes the method according to the invention for producing a vault-structured drum shell (100) for a washing machine, in which the above device is used:

The drum shell (100) is produced from a sheet metal blank from the coil, into which a hole pattern in the form of nested hexagons with a hole diameter of approximately 2 mm is first punched in three rectangular areas (not shown). Between these rectangles, strips without a hole pattern are provided with pocket-like openings, which later serve as inlet openings for scooping ribs (not shown) arranged inside the drum. At the edge of the sheet metal blank, a centering hole (not shown) is additionally punched. Subsequently, the sheet metal blank is rounded to form a hollow cylinder shell and welded to the abutting edges. This cylinder is preformed in an expansion process and thus provided for example with a chamfer (101) at the two edges.

The thus formed drum shell (101) is pre-centered by a robot (not shown) and placed on the receiving ring (23). In this case, a pre-adjustment in the radial direction takes place through the centering edge (23a). Subsequently, the bolt (25) is moved over the pneumatic cylinder in the centering hole and adjusts the jacket (100) in the circumferential direction. As a result, the exact position of the perforation is secured in the vertices of the applied arch structure.

After adjusting the drum shell, the traverse (18) is lowered by extending the two hydraulic cylinders (19) in the position (18 ') and pulls the expanding wedge (17) via the tie rod (16) downwards. As a result, the spreading jaws (12) are moved outwardly and the matrices (15) with the honeycomb-shaped support elements (15a) are in each case in a range of 100 ° on the inside of the drum shell (100). The pressure of the expansion jaws (12) is sufficient to hold the shell (100), therefore, the pin (25) is retracted and the receiving ring (23) via the hydraulic cylinder (24) lowered.

After the abutment of the support elements (15a), the three steel roller (28) coated with rollers are set against the drum shell (100) via the hydraulic cylinders (30) with a force of 60 kN. The positioning of the rollers takes place at points of the drum shell, which are opposite the edge (15b) of the dies (15). The turntable (6) is now rotated by the three-phase motor (9) by about 100 ° with adjacent rollers (28,29). Here is the Vault structure of the support elements (15a) embossed in the drum shell (100). Subsequently, the rollers (28,29) are moved back to their outer position, and the turntable (6) turned back to its original position. The receiving ring (23) is raised and carries the drum shell (100) again. Then the expanding wedge (17) is moved upwards and pulls the expanding jaws (12) inwards. Thereafter, the structured drum shell (100) can be removed from the device by a robot.

Claims (4)

1. Method for producing a dome-structured hollow cylinder, more especially a shell for the drum or the washing liquid bath of a washing machine, where the said hollow cylinder is pressed by a pressure roller (28, 29) against a die (15) with support elements (15a) for bringing about a domed structure and is set in rotation in opposition to a rotational movement of the pressure roller, characterised in that the support elements (15a) are disposed on at least-one carrier (die 15), the outside surface of which forms a cylinder segment and has a radius, which corresponds approximately to the radius of the hollow cylinder, in that the hollow cylinder (100) is adjusted in the circumferential direction, the precise position of a perforation in the corners of the domed structure thereby being assured, and in that once the hollow cylinder (100) has been adjusted, the dies (15) with the support elements (15a) are placed with their entire surface against the inside wall of the hollow cylinder (100), wherein the support elements (15a), in this way, during the rotation of the hollow cylinder and the resultant embossing of the domed structure through the pressure roller (29) being applied to the hollow cylinder (100), abut against its inside wall in a positive locking manner without any relative movement relative to the hollow cylinder (100).
2. Method for producing a dome-structured hollow cylinder according to claim 1, characterised in that three dies (15) are used and in that a pressure roller (28, 29) is associated with each die (15), wherein the pressure rollers (28, 29) are each offset by 120° and at the same time are pressed against the hollow cylinder.
3. Method for producing a dome-structured drum shell (100) of a washing machine drum according to claim 2, characterised in that the drum shell (100) with the adjoining support elements (15a) is rotated by approximately 100° for bringing about the domed structure.
4. Apparatus for producing a dome-structured hollow cylinder, more especially a shell (100) for the drum or the washing liquid bath of a washing machine, where this shell is pressed by a pressure roller (28, 29) against a die (15) with support elements (15a) and is set in rotation in opposition to the rotational movement of the pressure roller, wherein at least one cylinder-segment-shaped die (15) is provided, on which the support elements (15a) are disposed and the radius of which corresponds approximately to the radius of the hollow cylinder, characterised by a receiving ring (23) for the centred depositing of the hollow cylinder (100), wherein the receiving ring (23) includes a bolt (25), which is displaceable in the radial direction of the hollow cylinder (100) and is moved into a centring hole that is disposed in the hollow cylinder (100) and adjusts the hollow cylinder (100) in the circumferential direction, the precise position of a perforation in the corners of the domed structure to be mounted thereby being assured, and a positioning device (12, 16-19), via which the die (15), after being inserted into the interior of the hollow cylinder, is moveable in such a manner in the direction of its inside wall that all the support elements (15a) that are situated on the die (15) abut against the inside wall with their entire surface.

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