A load equalising device

Abstract: The invention provides a load equalising device for engraved rollers and doctor blades for use in a spreading machine for spreading or printing, the spreading machine being preferably suitable for use in the tanning and textile industries for depositing covering products such as pigments, resins, glues and the like on hide fabric or other types of stock, the spreading machine comprising a transport mechanism for the stock and a distribution assembly for the coating product to be deposited on the surface of the stock, the spreading machine preferably having a roller guide unit or doctor blade guide unit (1) mounted on a movable bridge (2), connected by a bolt (3) to the fixed structure of the machine and provided with a spider (4) which positions in sequence one of the engraved rollers (5) or doctor blades to face the belt (6) carrying the stock to be treated; the load equalising device being characterised in that it is constructed such that when the roller (5') or the blade (15) is positioned in the work area, in such a manner as to face the impression roller or the carrier belt, the roller (5') or the blade (15) while being attached to the spider is held by two lateral spring supports (7), the two lateral spring supports (7) being adjustable to equalise the load exerted on the engraved roller or doctor blade in operation as a consequence of its weight, or the weight of the support structure or other components present on the bridge, and to equalise variations in the width of the gap at a restricted zone (10) caused by variations in thickness of the stock or by elastic yield of the components of the machine, thereby to maintain the contact pressure exerted by the roller or blade on the stock to be treated at a substantially constant and pre-set value.

Description: The invention relates to a load equalising device for engraved rollers and doctor blades for spreading or printing as described in the preamble to claim 1. A load equalising device comprising the features of the preamble is known from GB 646 566 The use of machines known as "spreaders" for depositing coating (covering) products such as pigments, resins, glues and the like on hides, fabric and other materials is well known, particularly in the tanning and textile industries. Such machines typically comprise a transport mechanism for the material (commonly known as "stock") to be treated, and a device for depositing and distributing the coating product on the surface of the stock. According to the present state of the art, there are principally two types of devices for distributing thick or thin coating products, namely devices using rotating engraved rollers and devices using spreader or doctor blades. The transport mechanism for the hide, fabric or other stock to be treated typically comprises an impression roller or a sliding belt which is disposed opposite the engraved roller or doctor blade so as to form a restricted clearance (restricted zone) through which the stock passes. Among the parameters that influence the success of the operation of depositing the coating or covering product on the stock are the dimensions of the restricted clearance, i.e. the size of the gap between the impression roller or sliding belt and the stock, and the pressure exerted in the zone of contact between the engraved roller or doctor blade and the stock. In the present state of the art, various devices are known which can control the values of the foregoing two parameters, even in a continuous manner, but always with strictly pre-set values. An object of the present invention is to provide a device which compensates for variations in the dimensions of the restricted clearance resulting from the differing thicknesses of the stock and elastic yield of the mechanical components of the machine, and permits a continuous adjustment action such that the pressure of the engraved roller or doctor blade is maintained at a constant value and at an intensity pre-set by the operator according to the type of stock and coating product used. The object of the invention is attained by providing the engraved roller or doctor blade with lateral spring supports appropriately calibrated to afford optimum control of the load exerted on the engraved roller or doctor blade, resulting from its own weight, that of its supporting structure, and of any other equipment fitted to it. More particularly, the object of the invention is attained by the load equalising device as set out in the claims appended hereto. Advantageously, each of the two lateral spring supports comprises a supporting base for the end bolt of the engraved roller or doctor blade which is capable of moving along its longitudinal axis by the combined action of two forces, specifically the opposing action exerted by an adjustable preloaded spring and the action of a pin, also adjustable, placed inside the said spring. In operation, from a "zero point" position, which is determined when the engraved roller or doctor blade touches the impression cylinder or carrier blade without exerting pressure thereon, the operator, on the basis of the theoretical thickness of the hide, fabric or other stock to be treated, determines a "fixed zero" point, that is the minimum width of the gap at the restricted clearance for the passage of the stock, using the adjustable pin. Again, according to the type of stock to be treated, the operator then preloads the spring so as to determine a condition known as "moving zero", in which equilibrium is always maintained between the weight of the movable bridge structure supporting the roller or doctor blade and the opposing force exerted by the preloaded spring, independently of continuous variations in the width of the gap at the restricted clearance resulting from variations in thickness of the hide or fabric. An advantage of this arrangement is that the equalisation generated by the preloaded spring ensures that the engraved roller or doctor blade acts on the hide or fabric to be covered with a pressure of a substantially constant value. A further advantage of the foregoing arrangement is that of dampening the impact caused by the sudden rapid closing movement of the moveable bridge, after it has been raised to extract the hide or fabric or to change the engraved roller or doctor blade. This and other characteristics of the invention will become evident from the following description of one embodiment of the invention, given by way of an illustrative and non-limitative example, with reference to the accompanying drawings, of which: Figure 1 shows a front elevation of a spreading machine of the engraved roller type fitted with an equalising device according to one embodiment of the invention; Figure 2 shows a detailed view of the equalising device of the invention applied to an engraved roller machine; and Figure 3 shows a detailed view of an equalising device of the invention applied to a doctor blade machine. As shown in Figure 1, the engraved roller type spreading machine comprises a roller guide assembly 1, mounted on a movable bridge 2, connected by a bolt 3 to the structure of the machine and provided with a spider 4 which places in sequence one of the engraved rollers 5 to face the belt 6 for transporting the hide or fabric (for simplicity the hide or fabric are not shown). When the engraved roller 5' is in the operating position, although it remains attached to the spider, it is supported by two lateral spring supports 7, which represent a major novel characteristic of the invention. In detail, as shown in Figure 2, the lateral extremity 8 of the engraved roller 5 is preferably provided with a rolling contact bearing held in a bearing seat 9, the bearing seat being capable of moving on its longitudinal axis so as to control the width of the gap at the restricted clearance zone 10 where the stock to be treated passes through. In further detail, the bearing seat 9 is held elastically by the combined action of an adjustable preloaded spring 11 and a reciprocally coaxial adjustable pin, placed on the end of a mechanical or pneumatic control unit 13, which acts on the two elements with the results indicated. Advantageously, the two lateral bearing seats 9 are adjusted in a reciprocally independent manner. Figure 3 shows an alternative arrangement in which the aforementioned bearing seat 9 is applied to a doctor blade 15.

Claims: A load equalising device for engraved rollers and doctor blades for use in a spreading machine for spreading or printing, the spreading machine being preferably suitable for use in the tanning and textile industries for depositing covering products such as pigments, resins, glues and the like on hide fabric or other types of stock, characterised in that the spreading machine comprises a transport mechanism for the stock and a distribution assembly for the coating product to be deposited on the surface of the stock, the spreading machine preferably having a roller guide unit or doctor blade guide unit (1) mounted on a movable bridge (2), connected by a bolt (3) to the fixed structure of the machine and provided with a spider (4) which positions in sequence one of the engraved rollers (5) or doctor blades to face the belt (6) carrying the stock to be treated; the load equalising device being constructed such that when the roller (5') or the blade (15) is positioned in the work area, in such a manner as to face the impression roller or the carrier belt, the roller (5') or the blade (15) while being attached to the spider is held by two lateral spring supports (7), the two lateral spring supports (7) being adjustable to equalise the load exerted on the engraved roller or doctor blade in operation as a consequence of its weight, or the weight of the support structure or other components present on the bridge, and to equalise variations in the width of the gap at a restricted zone (10) caused by variations in thickness of the stock or by elastic yield of the components of the machine, thereby to maintain the contact pressure exerted by the roller or blade on the stock to be treated at a substantially constant and pre-set value. A device according to claim 1 further characterised in that each of the two lateral ends (8) of the engraved roller (5') or doctor blade (15), preferably provided with a roller contact bearing, is held on a bearing seat (9) capable of moving on its longitudinal axis so as to regulate the width of the gap of the restricted zone (10) and hence the distance between the engraved roller or said doctor blade and the underlying impression roller or carrier belt, according to the thickness of the hide, fabric or other stock to be treated, in order to maintain the contact pressure exerted by the said roller or blade on the stock at the substantially constant and pre-set value. A device according to claim 1 or claim 2 further characterised in that the bearing seat (9) is held elastically by the combined action of an adjustable preloaded spring (11) and pin (12), for example adjustable to preset height values. A device according to any one of the preceding claims further characterised in that both the adjustable preloaded spring (11) and the adjustable pin (12) are disposed on the end of, and controlled by, a mechanical or pneumatic device (13). A device according to any one of the preceding claims further characterised in that the two lateral bearing seats (9) are reciprocally adjustable in a independent manner.

Inventors: CENTOMO RICCARDO, CENTOMO, RICCARDO
Applicants: BERGI S P A, BERGI S.P.A.
Application year: 1999
Main classification: B05C11
IPC codes: B05C11, D06B15