A ROLLER AND A MACHINE FOR PEELING OR SHAPING POTATOES AND THE LIKE PRODUCTS

Abstract: A roller and a machine provided with a roller for peeling or shaping potatoes and similar products, the roller (8) comprising a cylindrical body (14) having a grinding surface (13) for contacting with the product (17) to be treated. To simplify the manufacture of the roller and enable the treatment of soft products, the grinding surface of the roller body has axially extending grooves (15) which form several treatment teeth (16) mutually spaced in the peripheral direction of the grinding surface.

Description: A roller and a machine for peeling or shaping potatoes and the like products The present invention relates to a roller for a machine for peeling or shaping potatoes and similar products, the roller comprising a substantially cylindrical body having a grinding surface for contacting with the product to be treated during the peeling or shaping. Even though the invention will be described in the following mainly in connection with the peeling of potatoes, the invention is likewise applicable to the peeling of other root crops, such as carrots, and fruits, such as apples. The invention is also applic- able to shaping e.g. Paris potato balls and other products that can be shaped. It is previously known to peel potatoes mech¬ anically by bringing them into contact with rotating grinding rollers which gradually grind off the peel. For example, Applicant's Finnish Patent Application No. 875 704 (European Patent Application 88312298.8) discloses a peeling machine comprising cylindrical grinding rollers arranged in the form of a drum. Not only the grinding rollers but also the drum rotates during the peeling, so that the potatoes roll on effectively and all peel-covered surfaces will make contact with the grinding rollers sooner or later. Applicant's Finnish Patent 67 657 (NL Patent Application 8 402 277) discloses a peeling/shaping machine comprising two parallel, co-operating pro¬ filed grinding rollers each provided with peripheral grooves, the groove pairs forming outlet openings for the ground potato balls. Both grinding rollers rotate in the same direction but at different speeds, so that the potato is caused to bounce repeatedly up into the air, thus turning a new peel-covered surface into contact with the rollers. In the prior art peeling machines, the grinding surface of the grinding rollers is formed by a layer of carborundum applied to a smooth cylindrical body possibly provided with peripheral grooves, so that the grinding surface is coarse and knobby. The layer of carborundum is usually glued on to a metal body. Such a grinding roller arrangement, however, has certain disadvantages. This is because the fixing of the carborundum layer is rather an extensive work stage and the glue joint is liable to break sooner or later, so that portions of the carborundum layer are detached from the roller body and may get among the treated products, especially when the peeling takes place at a relatively high speed, as suggested in the above-mentioned Finnish Patent 67 657. Another dis¬ advantage is that a grinding layer made of carbor- undum grinds the peel off the potato by a tearing effect, which makes this way of peeling less suitable for peeling and shaping softer fruits, such as apples, cucumbers, etc. The object of the present invention is to pro- vide a grinding roller which avoids the above- mentioned disadvantages and enables not only a simpler production but also peeling of soft fruits. This is achieved by means of a grinding roller according to the invention, which is characterized in that the grinding surface of the body has axially extending grooves which form several peeling or shaping teeth mutually spaced in the peripheral direction of the grinding surface. The invention is based on the idea that the "knobby" grinding surface of the grinding roller is formed by parallel grooves made in the grinding sur¬ face, so that the grinding surface performs the peel¬ ing of the product as a cutting operation in place of a tearing operation. The grinding surface of the grinding roller can thus be made integral with the roller body, and so there is no risk of the surface coming off, not even at high rotation rates. The roller material may thus be plastic, light metal, or the like. In addition, this arrangement enables the products to be peeled more gently, and so even relatively soft products can be peeled. A further advantage is that the surface of the treated products will be considerably smoother than a torn surface. The arrangement according to the invention also makes it possible to produce round balls by shaping cubic pieces of cucumber, melon, frozen vegetables, ice, etc. This has not been possible previously. The present invention also relates to a peeling machine for peeling or shaping potatoes or the like products, comprising - a frame, - at least two grinding rollers supported rota¬ tably by the frame and positioned essentially in parallel with and adjacent to each other for peeling or shaping the products, and - a driving device for rotating the grinding rollers, - the grinding rollers having a substantially cylindrical grinding surface. The peeling machine is characterized in that the grinding surface of at least one grinding roller has axially extending grooves which form several peeling or shaping teeth mutually spaced in the peri¬ pheral direction of the grinding surface. A peeling machine of this kind provides the advantages mentioned above in connection with the grinding roller. In the following the invention will be de¬ scribed in more detail with reference to the attached drawing, wherein Figures 1 and 2 are vertical views of a peeling machine provided with grinding rollers according to the invention as seen from two different directions; Figures 3 and 4 are a top view and a sectional view along the line IV-IV in Figure 3, respectively, of a roller pair according to the invention; and Figure 5 is an enlarged view of a portion of the grinding surface of the roller shown in Figure 4. The peeling machine shown in Figures 1 and 2 is of a construction described in Finnish Patent 67 657, and therefore its construction and operation will be described only in short in the following. The peeling machine comprises a vertical conveyor 1, an upper pair 2 of pre-grinding rollers, two lower pairs 3, 4 of grinding rollers, and a longitudinal conveyor 5. The upper pair 3 of rollers is intended for preliminary grinding of large potatoes which are first ground sufficiently and then slide down to the lower pair 4 of rollers, which grinds the potatoes into final potato balls, which slide down to the conveyor 5 and further to an outlet 6. Smaller potatoes slide directly down to the second lower pair of rollers. Potatoes smaller than the desired size of the balls as well as insufficiently ground potatoes and cleft potatoes fall down into a waste trough 7. Each pair 3, 4 of grinding rollers comprises two grinding rollers 8 and 9 which are mounted rotatably in a machine frame so that the shafts of the rollers are parallel with each other and so spaced from each other that only a small gap remains between the rollers. The rollers are coupled through suitable transmissions to motors not shown for rotat¬ ing the rollers in the same direction but at dif- ferent rotation speeds. The rollers are provided with peripheral grooves 11 semi-circular in cross-section and posi¬ tioned axially adjacent to each other. The roller grooves are arranged in pairs in line with each other so that several circular passages 12 of the same size as the potato balls to be produced are formed between the rollers. According to the invention, mutually spaced axial grooves 15 are cut in a grinding surface 13 of a body 14 of the grinding roller, so that a rim of peeling teeth 16 is formed in the grinding surface. The grooves are radially deeper than the peripheral grooves 11, so that the peripheral grooves form sharp semi-circular grinding edges 16a extending in the longitudinal direction of the roller. According to a preferred embodiment, the grooves 15 are cut in a plane A which forms an angle B, e.g. 6°, with respect to an axial plane. The slanting angle is selected so that the forward longitudinal grinding edge 16a of the tooth in the direction of rotation forms a cutting edge. The pair of rollers operates in the following way: When an unpeeled potato 17 falls down between the rollers, the roller 8 subjects the potato to a first grinding effect tending to lift it, and the roller 9 subjects the potato to a second grinding effect tending to push it downward. So the potato is caused to rotate about its centre of gravity, so that the roller 9, having a higher rotation speed, grinds the rotating potato on all sides. After the potato has been ground into a round potato ball 17 ' of a desired size, the ball falls down through the passage 12. The drawings and the description related there¬ to are only intended to illustrate the idea of the invention. In their details, the grinding roller and the peeling machine may vary within the scope of the claims. Accordingly, if required, cut grooves of some other type may be used, and the slanting angle of the grooves may be greater or smaller or possibly even zero. In certain cases, it may be appropriate that only one of the grinding rollers in a pair of rollers is constructed in accordance with the invention, whereas the other grinding roller, which rotates more slowly, may be provided with a conventional grinding surface. The grinding rollers according to the inven¬ tion can be used advantageously even in a drum peel¬ ing machine. In a specific machine, one roller has been rotated at 2,800 rpm and the other roller at 230 rpm. The rotation speeds may vary according to the kind of the products to be peeled and/or shaped. The expression "axially extending" is also intended to include e.g. spiral grooves cut in the grinding surface of the roller, which may give an advantageous result in certain cases.

Claims: Claims: 1. A roller for a machine for peeling or shap¬ ing potatoes and similar products, the roller (8) comprising a substantially cylindrical body ( 14) having a grinding surface ( 13 ) for contacting with the product (17) to be treated during the peeling or shaping, c h a r a c t e r i z e d in that the grinding surface (13) of the body (14) has axially extending grooves (15) which form several peeling or shaping teeth (16) mutually spaced in the peripheral direction of the grinding surface. 2. A roller according to claim 1, c h a r a c ¬ t e r i z e d in that the axially extending grooves (15) are cut in the body (14) to form sharp longit¬ udinal edges (16a) with the grinding surface (13). 3. A roller according to claim 1 or 2, the body (14) of the roller (8) comprising peripheral grooves (11) positioned axially adjacent to each other, c h a r a c t e r i z e d in that the axially extending grooves (15) are deeper than the peripheral grooves (11) in the radial direction of the roller. 4. A roller according to any of the preceding claims, c h a r a c t e r i z e d in that each one of the axially extending grooves (15) is positioned in a plane (A) deviating from the central line of the body (14) so that a forward edge (16a) of the teeth (16) in the direction of rotation of the roller (8) forms a cutting edge. 5. A machine for peeling or shaping potatoes and the like products, comprising - a frame ( 10) , - at least two grinding rollers (8,9) supported rotatably by the frame and positioned essentially in parallel with and adjacent to each other for peeling or shaping the products (17), and - a driving device for rotating the grinding rollers, - the grinding rollers having a substantially cylindrical grinding surface ( 13) , c h a r a c t e r i z e d in that the grinding sur¬ face (13) of at least one grinding roller (8) com¬ prises axially extending grooves (15) which form several mutually spaced peeling or shaping teeth (16) in the peripheral direction of the grinding surface. 6. A machine according to claim 5, c h a r a c¬ t e r i z e d in that the axially extending grooves (15) are cut in a body (14) so as to form sharp longitudinal edges (16a) with the grinding surface (13). 7. A machine according to claim 5, the cylindrical body (14) of the roller (8) comprising peripheral grooves (11) positioned axially adjacent to each other, c h a r a c t e r i z e d in that the axially extending grooves (15) of the grinding roller (8) are deeper than the peripheral grooves (11) in the radial direction of the roller. AMENDED CLAIMS [received by the International Bureau on 20 January 1994(20.01.94); original claims 1-7 replaced by amended claims 1-5 (2 pages)] 1. A roller for a machine for peeling or shaping potatoes and similar products, the roller (8) comprising a substantially cylindrical body (14) having a grinding surface (13) for contacting with the product (17) to be treated during the peeling or shaping, whereby the body (14) of the roller (8) has peripheral grooves (11) poεi- tioned axially adjacent to each other, c a r a c ¬ t e r i z e d in that the grinding surface (13) of the body (14) has radially inwardly extending, open axial grooves (15) which form several peeling or shaping teeth (16) mutually spaced in the peripheral direction of the grinding surface, said teeth forming sharp longitudinal edges (16a) with the grinding surface (13) , and that the axially extending grooves (15) are deeper than the peri¬ pheral grooves (11) in the radial direction of the roller. 2. A roller according to claim 1, c h a r a c ¬ t e r i z e d in that the axially extending grooves (15) are cut in the body (14) . 3. A roller according to any of the preceding claims, c h a r a c t e r i z e d in that each one of the axially extending grooves (15) is positioned in a plane (A) deviating from the central line of the body (14) so that a forward edge (16a) of the teeth (16) in the direction of rotation of the roller (8) forms a cut¬ ting edge. 4. A machine for peeling or shaping potatoes and the like products, comprising - a frame (10) - at least two grinding rollers (8, 9) supported rotatably by the frame and positioned essentially in pa- rallel with and adjacent to each other for peeling or shaping the products (17) , and - a driving device for rotating the grinding rollers, - whereby the grinding rollers having a substan¬ tially cylindrical grinding surface (13) and the cylind- rical body (14) of the roller (8) has peripheral grooves (11) positioned axially adjacent to each other, c h a r a c t e r i z e d in that the grinding surface (13) of at least one grinding roller (8) has ra¬ dially inwardly extending, open axial grooves (15) which form several, in the peripheral direction of the grinding surface mutually spaced peeling or shaping teeth (16) forming sharp longitudinal edges (16a) with the grinding surface (13) and that the axially extending grooves (15) of the grinding roller (8) are deeper than the peripheral grooves (11) in the radial direction of the roller. 5. A machine according to claim 4, c h a r a c - • t e r i z e d in that the axially extending grooves (15) are cut in a body (14) .

Inventors: ENGELHOLM TORBJOERN, ENGELHOLM, TORBJOERN
Applicants: ENGELHOLM TORBJOERN, T & S ENGELHOLM AB OY, OY T & S ENGELHOLM AB
Application year: 1993
Main classification: A23N7
IPC codes: A23N7, A23N15