GB2081303A

GB2081303A - Softening leather

Info

Publication number: GB2081303A
Application number: GB8119619A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-08
Filing date: 1981-06-25
Publication date: 1982-02-17
Also published as: IT8123424A0; IT1137835B; FR2488274A1; DE3030017A1; FR2488274B3; GB2081303B; DE3030017C2

Abstract

A milling device for softening leather has a horizontal rotary drum (10) which is rotatably received at both axial bearing ends (11, 12) in supporting bearings (13, 14). Channels (22, 23) which open out into the drum interior (21), are provided at the two bearing ends (11, 12). To channel (22) there is connected a dust extractor (40) with a cyclone separator (45) and a dust collection container (46) which is arranged downstream thereof. Extractor (40) is connected via a return line (41) to the other channel (23) so that the air which has been sucked from the drum interior (21) and has been freed of dust is returned at the other axial end. The drum jacket is provided with a cover for loading and unloading leather. <IMAGE>

Description

SPECIFICATION Rotary drum for the treatment of leather The invention relates to a milling device for leather comprising a horizontal rotary drum which has bearing ends which are preferably received in supporting bearings at both axial ends and which is driven in a rotating manner.

Known milling devices are tightly shut all around, including the axial front ends of the rotary drum. Only in the drum jacket zone do they have, for example, an opening which can be shut by means of a perforated, removable cover. Through this opening there is effected the introduction and removal of the material to be treated. The removable cover is perforated so that the drum interior is in communication with the environment of the milling device. Milling devices of this kind, which are also called milling vats, have the task of milling leather, by rotation of the rotary drum, in a dry manner in the drum interior and thus to soften it. The leather, which has already been subjected to preceding treatments, including a levelling treatment, has undergone final dyeing.During the levelling of the leather, fine leather fibres or leather chips stick to the leather, which then becomes detached during the soft-milling process in the milling device and accumulate as dust therein.

During this treatment, the accumulated dust passes to the outside through the cover, which is provided with holes, in the drum wall. This results in the room in which milling devices of this kind are placed, for example one behind the other, becoming very dusty. The extremely large accumulation of dust thus renders necessary special rooms in which only milling devices of this kind are then provided. Nevertheless, the nuisance caused by the dust to the operators working in these rooms is very great. Also, the devices are covered in dust to a very considerable extent so that thorough cleaning is indispensable at specific time intervals. All the same, the nuisance to the environment is considerable since completely isolated dust chambers are not realisable.For the rest, the treatment result is dependent on the air and space conditions of the room in which the milling device is located since, through the holes in each cover, the same air temperatures and air humidities prevail in the drum interior as in the environment. However, these conditions naturally fluctuate in dependence on the outside air parameters. For example, considered over the seasons, the air temperature and the air humidity vary considerably. Corresponding variations in the interior of the rotary drum lead to a nonreproduceable milling result. A differing grain formation comes about on the leather surface.

There furthermore come about irregular degrees of softness.

An object of the invention is to provide a milling device which avoids any effect on the environment due to dust accumulating in the drum interior and which renders possible a reproduceable treatment result, more especially a milling result, for the leathers to be treated, and a construction which is as simple, cheap and space-saving as possible.

According to the invention we provide a leather milling device comprising a horizontal rotary drum which has bearing ends which are preferably received in supporting bearings at both axial ends and which is driven in a rotating manner, characterised in that at the two bearing ends there are provided channels which open out into the interior of the rotary drum, and in that to one channel there is connected a dust extractor which is connected via a return line to the channel at the other front end and axially returns into the drum interior the air which has been sucked from the drum interior and has been freed of dust. Due to these measures, it is possible to free the drum interior from dust in an automatical process and to separate and collect the accumulated dust without the dust passing to the outside in an uncontrolled manner and contaminating the environment.This, in turn, makes it possible to provide within one room not only milling devices of this kind but also other equipment, including such which is normally sensitive to dust or any other contamination.

There is thus no need of a special room in which only the milling devices are accommodated. In this configuration, the cover on the drum jacket of each rotary drum is impermeable and, in its closed state, forms an at least substantially dust-tight seal.

A commercially customary rubbish container, which is as low in cost as possible, may serve as the dust collection container.

Due to the temperature regulating or controlling unit and/or the humidity regulating or controlling unit, it is rendered possible also to control the parameters of the temperature and the humidity of the air in the interior of the rotary drum, and this in a fully automatical process. This leads to an exactly reproduceable treatment result since the air in the interior of the rotary drum can now no longer, in adaptation to the room air, fluctuate with respect to the temperature and/or the humidity. At the same time, it is ensured that the temperature and humidity parameters can be pre-set, irrespective of the room conditions and the conditions of the external environment, so ideally as is desirable for the attainment of a desired treatment result.The respective regulating unit, comprising temperature and humidity sensors as well as a downstream heater and dehumidifying or humidifying units, which are triggered by the sensors, guarantees in an automatical process that the values set are kept constant. By this means, there is brought about a reproduceable milling result, in other words an optimum result that remains always constant, with the grain formation on the leather surface and the degree of softness always remaining constant, and this at a relatively low expenditure.

The provision of supporting bearings at the two ends is particularly simple, low in cost and spacesaving and yet stable to a high extent. The supporting bearings have only extremely small axial dimensions and there are left large throughchannels in the centre.

Further details and advantages will emerge from the following description.

Simply in order to avoid any unnecessary repetition, the full text of the claims has not been given above, but instead reference has been made thereto by just indicating the claim number, all claim features having however to be considered expressly disclosed at this point and to be material to the invention.

The invention will hereinafter be explained in more detail with reference to an exemplified embodiment of a milling device shown in the drawings, in which: FIGURE 1 shows a diagrammatical side view of the milling device, FIGURE 2 shows a diagrammatical, partly sectional top view of the milling device shown in Fig. and FIGURE 3 shows an enlarged axial longitudinal section of the milling device end zone that is to the left in Figs. 1 and 2.

The milling device shown in the drawings serves, in particular, for softening by milling treatment leather which has undergone final dyeing. This treatment is effected in an entirely dry state.

The milling device comprises a horizontal rotary drum 10 which, in the exemplified embodiment shown, is, with its bearing ends 11, 12, received at both axial ends in supporting bearings 13, 14 provided there. The rotary drum 10 is rotatingly driven by means of a diagrammatically indicated drive motor 1 5 with a belt pulley 1 6. For this purpose, there are provided on the outside of the rotary drum 10, and welded thereto, for example three rings which have been recessed in crosssection in a trough-shaped manner and into which the endless belts 1 7, 18 and 19, which have been pulled over the rotary drum 10 and the belt pulley 16, have been placed. The rotary drum 10 is accessible for the loading and removal of the material to be treated via an opening which can be shut by means of the cover 20.

At the two bearing ends 11 and 12, there are provided channels 22 and 23 which open out into the interior 21 of the rotary drum 10. The channels 22, 23 are each formed by axial hollow tubes 24 and 25 respectively, which have a large free cross-sectional area of passage in their interior. In Fig. 2 there is only diagrammatically shown a configuration in which the hollow tubes 24 and 25 are the direct carriers of the associated supporting bearings 13 and 14 respectively.

As can be seen in Figs. 1 and 2, in particular, there is connected to the channel 22, which is to the left therein, a special dust extractor 40 which is connected through a return line 41 to the channel 23 which is to the right in Figs. 1 and 2.

Air loaded with dust is sucked from the interior of the rotary drum 10 for dust removal by means of the dust extractor 40 through the left-hand channel 22 in the direction of the arrow 42 and is then introduced into the return line 41 in the direction of the arrow 43, and then the air which has been freed from dust is axially taken back again into the interior 21 of the rotary drum 10 at the right-hand end in Figs. 1 and 2 through the channel 23 provided there. As the arrow 44 indicates, ambient air is sudked from the outside into the right-hand channel 23 in the end zone of the rotary drum 10 that is to the right in Figs. 1 and 2.

The dust extractor 40 has a dust separator 45 which is designed as a cyclone separator and is provided with a dust collection container 46 arranged downstream thereof. The dust extractor 40 comprises a blower 47, more especially in the form of a centrifugal blower, which is provided above the dust separator 45 and is driven from a ? drive motor 48 which has a perpendicular axial orientation. The return line 41 is connected to the outlet of the blower 47.

Furthermore provided are a temperature regulating or controlling unit 50 and, in addition, a humidity regulating or controlling unit 60 in the flow of the air which is introduced through the right-hand channel 23 into the interior 21 of the rotary drum 10. The two units 50 and 60 are only diagrammatically indicated.

The temperature regulating or controlling unit 50 comprises a temperature sensor 51 and a heater 52 which is triggered by the temperature sensor 51.

The humidity regulating or controlling unit 60 comprises a humidity sensor 61 and a dehumidifying and/or humidifying means 62, for example a spraying unit for the production of a spray consisting of water. These units 50 and 60 with their respective individual components are known 'per se' assemblies, for which reason no further details concerning their illustration and description are given. What is more, these units 50, 60 emerge from the prior art. If one follows the flow of the air which has been freed from dust, the humidity regulating or controlling unit 60 is arranged downstream of the temperature regulating or controlling unit 50. The temperature regulating or controlling unit 50 is located at one front end of the rotary drum 10, namely at the end that is to the right in Figs. 1 and 2, in the run of the return line 41 where the return line 41 enters the right-hand channel 23.The humidity regulating or controlling unit 60 is provided inside the channel 23, which is opposite to the other channel 22, and, if one follows the flow of the fresh air supplied, as shown by the arrow 44, is upstream of the point where the return line 41 opens into the right-hand channel 23. V Thanks to this configuration, it is possible to carry out the milling treatment of the leather, which has undergone final dyeing, in an automatically controlled process. As a consequence of the preceding levelling treatment, the leather introduced into the rotary drum 10 is provided with very fine leather chips or leather fibres which become evident as dust. During the milling treatment, that is to-say the soft milling of the leather, this dust is precipitated in the interior of the rotary drum 10 and, in the known milling devices, normally passes to the outside during the process through perforated holes in the cover 20.

For this reason, the nuisance caused by dust to the environment is enormous in known devices of this kind, a reproduceable treatment result also being impossible because the interior 21 of the rotary drum 10 of known milling devices is in constant communication with the environment and the ambient temperature and/or the room humidity, which may both change, are therefore also communicated to the interior of the rotary drum.

By contrast, the nuisance caused by dust is eliminated in the milling device according to the invention. Furthermore, both the temperature and the humidity can be set in a reproduceable manner in the interior 21 of the rotary drum 10 and can be kept constant at pre-set values so that, in this respect, there is ensured a reproduceable treatment result that always remains constant, irrespective of the room conditions outside the rotary drum 10.

The leather that has been introduced into the rotary drum 10 and is to be milled soft by the dry method is treated accordingly during the rotation of the rotary drum 10. During this process, fresh air is sucked in, as required, from the outside through the channel 23, which is to the right in Figs. 1 and 2, in the direction of the arrow 44 by means of the dust extractor 40 and into the interior 21 of the rotary drum and air loaded with dust is sucked from the interior 21 of the rotary drum 10 through the channel 22 in the direction of the arrow 42. The dust is filtered by means of the dust separator 45 and is received in the dust collection container 46, which may be a simple conventional rubbish container.The air which has been freed of dust passes in the direction of the arrow 43 through the return line 41 and, at least the major part thereof, is returned through the right-hand channel 23 into the interior 21 of the rotary drum 10. The temperature sensor 51 measures the actual temperature of the air inside the return line 41. If it differs from the nominal temperature, the heater 52 is triggered accordingly so that, as the air passes through the heater 52, the air is heated, for example, correspondingly. In this connection, it is obvious that another temperature sensor may be part of the temperature regulating unit 50, which sensor sits behind the outlet of the heater 52 and, there, detects the actual temperature and, together with the temperature sensor 51, carries out a differential measurement.

The air passing into the right-hand channel 23 is also monitored with respect to its degree of humidity and, depending on the result, is reregulated. This happens by means of the humidity regulating or controlling unit 60. The humidity sensor 61 detects the humidity content of the air and, depending on the result, triggers the means 62 for dehumidification and/or humidification. It is obvious that all the setting control functions are combined in a control cabinet which is not shown in detail.

Hereinafter, the special feature of the mounting will be explained with reference to Fig. 3 and therein by the example of the left-hand supporting bearing 13; it is obvious that the right-hand supporting bearing 14 is designed in the same way.

The supporting bearing 13 comprises an internal bearing ring 26 and an external supporting ring 27 which is stationary in relation thereto and which is coaxially aligned with the bearing ring 26 and engages over this latter on the outside. On its external circumferential surface, the bearing ring 26 has a bearing surface which consists of a recessed annular groove 28. In a corresponding manner, on its internal circumferential surface, the supporting ring 27 is also provided with a bearing surface in the shape of a recessed annular groove 29. The two annular grooves 28, 29 co-operate for the transverse mounting and the longitudinal mounting of the rotary drum 10, namely in such a way that there run in these annular grooves 28, 29 bearing elements in the shape of rolling elements which, in a ball-type turntable design, consist herein of balls 30.

The stationary external supporting ring 27 is held in a supporting part 32 in the shape of a sleeve by means of an elastic intermediate layer 31 which is designed as a rubber mounting. This supporting part 32 sits on a lower foot rest 33, by which it is carried together with the stationary external supporting ring 27.

The bearing ring 26 at the drum end is detachably secured to a drum-end front disc 35 by means of screws 34. The front disc 35 is fixedly connected, for example welded, to the facing front wall 36 of the rotary drum 10. On the axial side that is directed away from the rotary drum 10, the front disc 35 carries an axial centring shoulder 37, on which the bearing ring 26 is centred. In their centres, the front disc 35 and the front wall 36 are provided with central passage ports 38 and 39 respectively, which are large in diameter. On the axial side that is directed away from the rotary drum, the bearing ring 26 and the supporting ring 27 are covered by a ring cover 70 which axially covers both rings and which is detachably secured to the stationary supporting ring 27 by means of screws 71.The ring cover 70 is also provided in the centre with a passage port 72 which is large in diameter.

As can be seen in Fig. 3, the hollow tube 24 shown therein and containing the channel 22 is fixedly attached, for example welded, to the ring cover 70. The hollow tube 24 penetrates the passage port 38 in the front disc 35 with a slight radial clearance. In the axial direction, the hollow tube 24 extends as far as the passage port 39 in the front wall 36 of the rotary drum 10. In the opposite sense thereto, the hollow tube 24 extends in the axial direction continuously as far as the through-port 72 in the ring cover 70 which, at the end of the hollow tube 24 that is to the left in Fig. 3, has been placed thereon and has been welded together with the latter.The hollow tube 24 is consequently independent of the play in'the supporting bearing 13 and particularly of any movement which the bearing ring 26 at the drum end carries out in relation to the foot part 33. The rubber mounting 31 has the special task of compensating for any slight misalignments or other axial inaccuracies, absorbing vibrations, equalising unbalances, etc. Due to the fact that in the end zone that is to the right in Fig. 3, the stationary hollow tube 24 does not bear directly against the passage port 38 in the front disc 35 but that a radial clearance is provided, this movability of the rotary drum 10 with the bearing ring 26 relative thereto is not obstructed. It is kept away from the hollow tube 24 and the line which is connected thereto by means of conventional line connections.Therefore, the hollow tube 24 is stationary whereas, when driven, the rotary drum 10 can rotate relative thereto.

The rotary drum 10 has an internal baffle wall 73 which is held on the front wall 36. This baffle wall has at least a slightly conical shape, with the cone vertex, which lies on the drum axis, directed towards the interior 21 of the rotary drum 10. At least in the zone of the channel 22, the baffle wall 73 extends at an axial distance from the front wall 36. On the radial zone over which the channel 22 extends with respect to the cross-section, the baffle wall 73 has no passage, whereby the baffle function is thus ensured.By contrast, on the surface zone which lies at a radial distance outside the diameter zone of the channel 22, the baffle wall 73 is provided with relatively large passage ports 74, for example perforated holes, so that, through the passage ports 74, air loaded with dust can be easily and without any trouble sucked from the interior 21 of the rotary drum 10 through the channel 22. At the same time, it is avoided that in the zone where the sucking action is strongest, in other words in the cross-sectional area of the channel 22, the leather in the interior 21 is sucked directly, which, if the passage ports were provided in this cross-sectional area, would then cause the latter to be blocked and thus the suckingsff of dust-laden air to be impeded. This is consequently prevented by the described passage ports 74.

The supporting bearing 14, which is to the right in Figs. 1 and 2, is exactly the same in design as the described supporting bearing 13 shown in Fig.

3. Altogether, there thus comes about a low-cost, particularly simple and above all stable mounting which is at the same time capable of absorbing any misalignments and vibrations and which renders possible at both ends of the rotary drum 10 the provision of channels 22, 23 for the sucking-off or return of air which are extremely large in diameter. At the same time, mounting elements are used in a simple, low-cost and compact construction to receive and fix the hollow tubes 24, 25 at both ends. The supporting bearings 1 3, 14 at both ends require only very small axial dimensions so that the entire axial size of the device can be kept very small.

Claims

1. A leather milling device comprising a horizontal rotary drum which has bearing ends which are preferably received in supporting bearings at both axial ends and which is driven in a rotating manner, characterised in that at the two bearing ends (11, 12) there are provided channels (22,23) which open out into the interior (21) of the rotary drum (10), and in that to one channel (22) there is connected a dust extractor (40) which is connected via a retum line (41) to the channel (23) at the other front end and axially returns into the drum interior (21) the air which has been sucked from the drum interior (21) and has been freed of dust.

2. A milling device as claimed in Claim 1, characterised in that the dust extractor (40) comprises a dust separator (45), more especially a cyclone separator, with a dust collection container (46) arranged downstream thereof.

3. A milling device as claimed in Claim 1 or 2, characterised in that the dust extractor (40) comprises a blower (47), for example a centrifugal blower, which is arranged above the dust separator (45).

4. A milling device as claimed in one of Claims 1 to 3, characterised by a temperature regulating or controlling unit (50) and/or a humidity regulating or controlling unit (60) in the flow of the air which is introduced through the channel (23) into the interior (21) of the rotary drum (10).

5. A milling device as claimed in Claim 4, characterised in that the temperature regulating or controlling unit (50) comprises a temperature sensor (51) and a heater (52) which is triggered by the latter.

6. A milling device as claimed in Claim 4, characterised in that the humidity regulating or controlling unit (60) is arranged downstream of the temperature regulating or controlling unit (50) in the flow direction of the air.

7. A milling device as claimed in Claim 4 or 6, characterised in that the humidity regulating or controlling unit (60) comprises a humidity sensor (61) and a dehumidifying and/or humidifying means (62), more especially a spraying unit for the production of a spray, which is triggered by the latter.

8. A milling device as claimed in one of Claims 4 to 7, characterised in that the temperature regulating or controlling unit (50) is provided at one front end of the rotary drum (10) in the return line (41) where the return line (41) enters the channel (23).

9. A milling device as claimed in one of Claims 4 to 8, characterised in that the humidity regulating or controlling unit (60) is provided within the channel (23) which is opposite to the channel (22) containing the dust extractor (40), preferably upstream of the point of entry of the return line (41) in the flow direction of the fresh air that is supplied.

10. A milling device as claimed in one of Claims 1 to 9, characterised in that each supporting bearing (13, 14) has a bearing ring (26) which is secured to the rotary drum (10) and a stationary supporting ring (27) which is coaxial with the bearing ring (26) and engages over this latter, the bearing ring (26), preferably on its external circumferential surface, and the supporting ring (27), preferably on its internal circumferential surface, having bearing surfaces (28 and 29 respectively) which co-operate with each other for the transverse mounting and/or the longitudinal mountingofthe rotary drum (10).

11. A milling device as claimed in Claim 10, characterised by bearing elements (30), more especially rolling elements, preferably a ball-type turntable, which elements are arranged between the bearing ring (26) and the supporting ring (27).

12. A milling device as claimed in Claim 10 or 11, characterised in that the stationary supporting ring (27) is held by means of an elastic intermediate layer (31), for example a rubber mounting, in a supporting part (32), preferably a sleeve, which is secured to foot rests (33) and is carried by these.

13. A milling device as claimed in one of Claims 10 to 12, characterised in that the bearing ring (26) is detachably secured to a front disc (35) at the drum end and is preferably centred on an axial shoulder (37) thereof.

14. A milling device as claimed in one of Claims 1 to 13, characterised in that the bearing ends (11, 12) comprise hollow tubes (24 and 25 respectively) which have a large internal crosssectional area of passage and form the channels (22 and 23 respectively).

1 5. A milling device as claimed in Claim 14, characterised in that the hollow tubes (24, 25) are the carriers of the bearing rings at the drum ends.

16. A milling device as claimed in Claim 14, characterised in that the hollow tubes (24, 25) are held on the stationary part of the supporting bearings (13 and 14 respectively), more especially on the supporting ring (27).

17. A milling device as claimed in one of Claims 1 3 to 1 6, characterised in that the front disc (35) at the drum end and the front wall (36) of the rotary drum (10) have central passage ports (38 and 39 respectively), in which the hollow tube (24) engages.

18. A milling device as claimed in one of Claims 10 to 17, characterised by a ring cover (70) which covers the supporting bearing (13) on the axial side that is directed away from the rotary drum (10) and which is secured, more especially in a detachable manner, to the stationary supporting ring (27).

1 9. A milling device as claimed in Claims 17 and 18, characterised in that the ring cover (70) has a central passage port (72), and in that the hollow tube (24) extends in the axial direction through the passage port (72) in the ring cover (70) and is secured to this cover.

20. A milling device as claimed in one of Claims 1 to 19, characterised in that the rotary drum (10) has at each front end an internal baffle wall (73) which is held on the front wall (36) and which, at least in the zone of the channel (22), extends at an axial distance from the front wall (36).

21. A milling device as claimed in Claim 20, characterised in that in the radial zone of the channel (22), the baffle wall (73) has no passage and, on a surface area which is outside the channel (22) with a radial clearance, is provided with passage ports (74Y, for example perforated holes.

22. A leather milling device substantially as described herein with reference to the accompanying drawings.