PEELING DEVICE FOR POTATOES AND SIMILAR PRODUCTS

Abstract: A peeling device for potatoes and similar products, comprising rotating peeling rolls (2) coated with a grinding material and mounted in the form of a semi-cylinder forming a trough through which the product is conveyed forward by means of a screw feeder (3) from the inlet (6) towards the outlet (7). On account of the small diameter of the peeling rolls, the product moves over the rolls with a movement (11) which is necessary for even peeling, and the trough has a tight bottom, which is necessary in the peeling of small products. The grain size of the grinding coating of the peeling rolls decreases from the inlet towards the outlet. The screw feeder is provided with double threading (16) at the outlet end in order to provide a more even discharge of the product. The peeling rolls are actuated by means of belts (14): half of the belts actuate every second roll, the other half actuating the rest of them. The peeling can take place without supply of water, as the peeling rolls rotate at a high speed so that the peelings are slung therefrom.

Description: Peeling device for potatoes and similar products It is previously known to peel potatoes and similar products mechanically with various rotating grinding means. A so-called roll drum peeler is provided with peeling rolls positioned in such a way that they form a cylindrical drum in which the product is conveyed forward. In addition to the peeling rolls, even the drum rotates and prevents thereby the product from ceasing to move between two rolls and from being ground uneven¬ ly. The diameter of the rolls is usually 100 to 150 mm. The rotation speed of the rolls varies generally between 150 and 1000 rotations per minute. A screw feeder is generally used for conveying the product through the peeling machine. In another type of peeling device, roll peeler, the peeling rolls are positioned in such a way that they form a semi-cylindrical trough. The peeling rolls are provided with various longitudinally disposed ridges or curved in various ways to make the product move as necessary. However, these arrangements subject the product to jerky movements, which impairs the quality of the product, e.g. its keeping quality. In these machines, water is normally used during the peeling process mainly to keep the rolls free from peelings. However, this results in a large amount of waste water. The present invention relates to an improved roll peeler in which jerky movement of the product has been eliminated. The mobility of the product is ensured by keeping the diameter of the peeling rolls sufficient¬ ly small so that the product moves easily over the rolls. Because of a relatively high rotation speed of the peeling rolls, the peelings are slung from the rolls and the rolls remain clean. Water is not needed at all during the actual peeling process, but is needed only afterwards for rinsing, wherefore the amount of produced waste water is minimal. The peeling waste has a more solid consistency and can be used for animal feed or the like. In addition, the small diameter of the rolls renders the bottom of the trough tight, which makes it possible to peel even products of a small size (small potatoes) . The peeling effect can be enhanced by coating the grinding rolls with grinding material having a grain size that gradually decreases during the process. Thus the product is rapidly peeled by the coarse-grained grinding material at the beginning, and is given a smooth surface by the more fine-grained grinding material at the end of the process. The product is conveyed through the peeling device by means of a screw feeder. To ensure that the product is kept mobile, a certain minimum pitch is required for the thread of the screw feeder (250 to 300 mm). The outlet end of the screw feeder can, however, be provided with a double thread. This divides the product into two parts in such a manner that the product is discharged twice per each rotation of the screw feeder. The peeled product is thus discharged at a more regular pace, which is significant, for example, when the product is sorted manually. The invention further relates to a method of actuating the peeling rolls. The cone belts between the belt pulley of the motor and the belt pulleys of the peeling rolls are divided into two groups so that one group actuates every second peeling roll and the other group the rest of them. Larger friction surfaces are thus provided between the cone belts and the belt pulleys, whereby sufficient motive power is achieved at low costs. Construction and operation of the invention An embodiment of the invention will be described in the following. Numbers referring to the accompanying drawings will be given in brackets. Figure 1 is a partial cross-section of the peeling device described. Figure 2 is a partly sectional view of the peeling device in the longitudinal direction. The machine comprises a frame (1) in which peeling rolls (2) are positioned horizontally and paral- lelly in such a manner that they form a semi-cylinder (trough). The rolls are disposed close to each other, the distance between them being only 4 to 6 mm. Each peeling roll is suspended from the frame and rotatable around its longitudinal axis. At one end of the machine, there is an inlet (6) for introducing the unpeeled product into the trough, and at the opposite end, there is an outlet (7) for the peeled product. Inside the trough formed by the peeling rolls, there is provided a screw feeder (3) which is rotatably mounted in the longitudinal direction for conveying the product in the longitudinal direction of the machine from the inlet (6) over the rotating peeling rolls towards the outlet (7) . The screw feeder is positioned as close to the peeling rolls as possible. The screw feeder is driven by an electric motor (10) provided with gearing, via a chain (15). The screw feeder is double threaded (16) at the outlet end to allow the peeled product to be discharged at a more regular pace. The screw feeder can be provided with an electronic or mech¬ anical speed control to optimize the peeling process for products of different types. The grinding coating of the peeling rolls is coarse-grained at the inlet end, more fine-grained at the middle portion, and very fine-grained at the outlet end. This improves the peeling effect at the beginning of the process and gives the peeled product a smoother surface, which essentially enhances its keeping qualities. The diameter of the peeling rolls is 50 to 100 mm, preferably 60 mm. Because of the small diameter, the triangular gaps (4) between the rolls and the screw feeder are very small. The even and tight bottom thus formed is particularly important, for example, in the peeling of small potatoes. All peeling rolls have the same direction of rotation. Combined with the small diameter, this makes the movement (11) of the product such that, near the bottom, it follows the rotating rolls until it reaches a sufficiently high position in the lateral direction, whereafter it rolls or slides again to the bottom. The entire skin surface is ground without that the product ceases to move or without unnecessary jerky movements. The peelings (12) are slung from the rolls; they fall on a conveying belt (8) and are then carried away. Owing to the small diameter of the peeling rolls and the high rotation speed (800 to 1000 rotations per minute), the peelings are slung from the rolls, and thus the rolls are kept clean. This allows the peeling to take place completely without water. The rolls are actuated by four cone belts (14), all of which run from the belt pulley of the electric motor (9) round the belt pulleys (5) of the peeling rolls. The belt pulleys provided with two grooves and fixed on the shafts of the peeling rolls are positioned in such a manner that, on every second shaft, the pulley is disposed further away in the longitudinal direction of the shaft compared with the preceding one; two of the belts thus actuate every second peeling roll, while the other two actuate the rest of the rolls. This arrange¬ ment allows the use of belt pulleys having a larger diameter than the peeling rolls. Consequently, the belts have a larger contact surface, wherefore a higher motive power is provided. In addition, the rolls can be made to rotate at different speeds by means of cone belt pulleys of different sizes, which enhances the peeling effect. In this embodiment, the tension of the belts is adjusted by means of auxiliary belt pulleys (13).

Claims: Claims 1. A peeling device for potatoes and similar products, comprising a plurality of peeling rolls (2) suspended substantially horizontally and parallelly from a frame (1), whereby they form a trough having the form of a cylinder sector, preferably a semi-cylinder, said peeling rolls being made to rotate by means of belts (14) mounted on belt pulleys (5) at one end of the peel- ing rolls, c h a r a c t e r i z e d in that the belt pulleys (5) have a larger diameter than the peeling rolls, the belt pulleys (5) on every second peeling roll being positioned further away substantially in the lon¬ gitudinal direction of the peeling roll. 2. A peeling device according to claim 1, c h a r a c t e r i z e d in that the belt pulleys (5) are positioned on two parallel sectional surfaces of the apparatus. 3. A peeling device according to claim 1 or 2, c h a r a c t e r i z e d in that the belt pulleys (5) positioned on the two parallel sectional surfaces of the apparatus are of different size. 4. A peeling device according to any one of claims 1 to 3, c h a r a c t e r i z e d in that the peeling rolls (2) have a relatively small diameter, preferably 50 to 100 mm. 5. A peeling device according to any one of claims 1 to 4, c h a r a c t e r i z e d in that the peeling rolls (2) are provided with a coating for subjecting the product to a grinding effect to remove its skin, said coating having the greatest grain size near the inlet (6) and gradually smaller grain size towards the outlet (7) . 6. A peeling device according to any one of claims 1 to 5, c h a r a c t e r i z e d in that the screw feeder (3) is provided with double or multiple threading (16) at its outlet end.

Inventors: NORRVIK ELMER EGIL, NORRVIK, ELMER, EGIL
Applicants: NORRVIK ELMER EGIL, NORRVIK, ELMER, EGIL
Application year: 1995
Main classification: A23N7
IPC codes: A23N7