Drum for wet processing skins and hides

Abstract

 The drum for carrying out wet processing of skins and hides comprises: a substantially cylindrically shaped shell (10), mounted so as to rotate about its longitudinal axis (12) and formed by a side wall (14) closed at the ends by respective end walls (16), so as to define an internal cavity (18); and a plurality of paddles (20) which protrude from the internal surface of the side wall (14) within the cavity (18) and are capable of exerting a mechanical action on the skins during rotation of the shell (10). There are three such paddles (20) which are oriented radially and are offset circumferentially from one another by approx. 120°.

Description

[0001] The present invention relates to a drum for carrying out wet processing of skins and hides, for example tanning, dyeing and liming.

[0002] More specifically, such a drum comprises:

• a substantially cylindrically shaped shell, mounted so as to rotate about its longitudinal axis and formed by a side wall closed at the ends by respective end walls, so as to define an internal cavity, and
• a plurality of paddles which protrude from the internal surface of the side wall within said cavity and are capable of exerting a mechanical action on said skins during rotation of the shell.

[0003] US patent 6 151 932 describes a drum of this type provided with four paddles, the bases of which are positioned on the internal surface of the side wall at, in each cross-section, the vertices of an imaginary square, in such a manner that two paddles located at diametrically opposed points are parallel to one another and perpendicular to the other two paddles, which are likewise located at two diametrically opposed points and are parallel to one another. The paddles are furthermore arranged eccentrically, i.e. they lie on planes which do not intersect the longitudinal axis of the cylindrical shell.

[0004] However, such an arrangement of the paddles means that skin and hide processing can proceed by rotating the shell in just one direction, such that the material being processed tends to roll up on itself, is processed in a nonuniform manner and is difficult to discharge on completion of the operating cycle.

[0005] With the aim of overcoming such disadvantages, it is a subject of the present invention a drum of the type stated at the beginning of the present description and characterised in that there are three such paddles which are oriented radially and are offset circumferentially from one another by approx. 120°.

[0006] Radial orientation of a paddle is intended to mean that it lies on a plane which substantially intersects the longitudinal axis of the shell.

[0007] Radial orientation of the three paddles makes it possible to rotate the drum alternately in both directions, in such a manner as to spread out the skins, thereby improving the uniformity of processing and facilitating discharge operations on completion of the operating cycle.

[0008] The cylindrical shell of the drum of the invention may be rotated at low speed while nevertheless ensuring excellent processing results, therefore enabling considerable energy savings. Moreover, thanks to the drum of the invention, it is possible to reduce the quantity of liquid to be used in the processing bath and conversely to increase the quantity of skins and hides which may be processed in one operating cycle, thereby making it possible to achieve further savings and increase the efficiency of the treatment process.

[0009] Further advantages and features of the present invention will become clear from the following detailed description, which is provided purely by way of non-limiting example, with reference to the attached drawings, in which:

Figure 1 is a schematic perspective view of a shell of a drum of the invention,

Figure 2 is a schematic perspective view of a variant embodiment of a drum of the invention, and

Figure 3 is a schematic perspective view of another variant embodiment of a drum of the invention.

[0010] A drum for wet processing skins and hides, comprises (Figure 1) a shell 10 of substantially cylindrical shape, mounted so as to rotate about its longitudinal axis 12, and formed by a side wall 14 closed at the ends by respective end walls 16 (one of which has not been shown in Figure 1 for clarity's sake), so as to define an internal cavity 18. The drum is furthermore provided in per se known manner with actuating means, not shown in the drawings, capable of setting it in rotation about the axis 12.

[0011] Three paddles 20 protrude from the internal surface of the side wall 14 within the cavity 18 and are capable of exerting a mechanical action on the skins during rotation of the shell 10 in such a manner as to assist the action of the chemical agents present in the processing bath.

[0012] The paddles 20 are oriented radially and are offset circumferentially from one another by approx. 120°. Each paddle 20 is of a substantially rectangular shape defined by a pair of radial sides 22 and by a pair of sides 24, 26 parallel to the longitudinal axis 12 of the shell 10, which constitute the root and the free edge of the paddle 20, respectively.

[0013] The side 26 parallel to the longitudinal axis 12 of the shell 10, which constitutes the free edge of each paddle 20, is rectilinear.

[0014] The length of the radial sides 22 of each paddle 20, which defines the height thereof, is advantageously between one third and one sixth of the external diameter of the side wall 14 of the shell 10.

[0015] Figure 2 shows an alternative embodiment of the invention, in which identical numbers to those used in the previous drawing identify identical or equivalent parts.

[0016] The only substantial difference relative to the drum of Figure 1 resides in the fact that the side 26 parallel to the longitudinal axis 12 of the shell 10, which constitutes the free edge of each paddle 20, is shaped, in particular in the manner of crenellations. Said shape further improves agitation of the skins during processing, promoting the penetration therein of the chemical agents present in the processing bath, for example in order to carry out a liming treatment.

[0017] Figure 3 shows a further embodiment of the invention, in which identical numbers to those used in the previous drawings identify identical or equivalent parts.

[0018] In this case, between each pair of adjacent paddles 20, there is arranged a respective row of pegs 28 which extends parallel to the longitudinal axis 12 of the shell 10.

[0019] The pegs 28 are of a lower height than the length of the radial sides 22 of the paddles 20, such that they cannot damage the skins being processed even when a reduced quantity of bath liquid is present. The drum shown in Figure 3 is suitable, for example, for carrying out tanning and dyeing treatments.

[0020] Naturally, the principle of the invention remaining the same, the details of construction and forms of embodiment may be varied widely with respect to those described, which have been given purely by way of example, without thereby departing from the scope of the claims.

Claims

1. A drum for carrying out wet processing of skins and hides, comprising:

- a substantially cylindrically shaped shell (10), mounted so as to rotate about its longitudinal axis (12) and formed by a side wall (14) closed at the ends by respective end walls (16), so as to define an internal cavity (18), and

- a plurality of paddles (20) which protrude from the internal surface of the side wall (14) within said cavity (18) and are capable of exerting a mechanical action on said skins during rotation of the shell (10),
said drum being characterised in that there are three such paddles (20) which are oriented radially and are offset circumferentially from one another by approx. 120°.

2. A drum according to claim 1, characterised in that each paddle (20) is of a substantially rectangular shape defined by a pair of radial sides (22) and by a pair of sides (24, 26) parallel to the longitudinal axis of the shell which constitute the root and the free edge of the paddle (20), respectively.

3. A drum according to claim 2, characterised in that the length of the radial sides (22) of each paddle (20) is between one third and one sixth of the external diameter of the side wall (14) of the shell (10).

4. A drum according to claim 2 or claim 3, characterised in that the side (26) parallel to the longitudinal axis (12) of the shell (10), which constitutes the free edge of each paddle (20), is rectilinear.

5. A drum according to claim 2 or claim 3, characterised in that the side (26) parallel to the longitudinal axis (12) of the shell (10), which constitutes the free edge of each paddle (20), is shaped.

6. A drum according to any one of the preceding claims, characterised in that, between at least one pair of adjacent paddles (20), there is arranged a respective row of pegs (28) which extends parallel to the longitudinal axis (12) of the shell (10).

Drawing