TURNTABLE CONVEYOR

Description

[0001] The present invention relates to a conveyor, comprising a helical conveying path having an upright central axis, a frame and an endless conveying member for transporting a product through the conveying path which conveying member is displaceable with respect to the frame.

[0002] Such a conveyor is known from EP 1 902 978. The known conveyor is provided with a slat belt as an endless conveying member, which can transport products in vertical direction. In case of transporting weak, block-shaped products, these will be twisted somewhat during travelling through the helical conveying path. For transporting relatively long, wide and rigid, block-shaped products the conveyor will preferably be provided with a conveying path including a relatively large radius and / or a small inclination, since this type of products tends to rest on the slat belt through only two corners located opposite to each other in diagonal direction of the product; more specifically: the highest corner at the inner bend and the lowest corner at the outer bend of the helical conveying path. The inclination in the inner bend is steeper than the inclination in the outer bend. In practice a product will seek a third supporting location, such that it may wobble or even turn over. Another disadvantage is that at the corners of the product relatively high forces may locally act on the conveying member.

[0003] US 3 857 476 is related to a conveyor which has a pliable endless belt adapted to negotiate a multiplicity of helical convolutions in a non-planar or twisted mode, and is also adapted to negotiate straight runs tangentially continuing with the helical rungs, with the belt in the straight runs operating in a flat planal untwisted mode. The belt is composed of a link-type chain having pins and rollers with tolerances among the component operating parts as to provide extension and contraction capabilities and of chain-connected separate and independent slats, supported by fixed helical track bars substantially at the mid-length of the slats, leaving the free ends of the slats free to flex toward conformity with flat-bottomed objects transported, whereby slack is introduced in each convolution to prevent snubbing or binding.

[0004] An object of the invention is to provide a conveyor which is able to transport rigid, block-shaped products in a stable manner.

[0005] This object is achieved with the conveyor according to the invention, which is defined in claim 1.

[0006] It is noted that the word helical indicates that the conveying path in this portion of the conveyor is climbing continuously.

[0007] The invention will hereafter be elucidated further with reference to drawings showing an embodiment of the invention very schematically. Fig. 1 is a side view of a conveyor. Fig. 2 is a plan view of the conveyor according to Fig. 1, including some products that are transported. Figs. 3-6 are cross-sectional views along the respective lines III-III, IV-IV, V-V and VI-VI in Fig. 2. Figs. 7-10 are cross-sectional views similar to Figs. 3-6 of an alternative conveyor. Figs. 11-14 are cross-sectional views similar to Figs. 3-6 of another alternative conveyor. Figs. 15-18 are cross-sectional views similar to Figs. 3-6 of an embodiment of a conveyor according to the invention. Figs. 19-22 are cross-sectional views similar to Figs. 15-18 of still another alternative conveyor. Figs. 23-26 are cross-sectional views similar to Figs. 15-18 of still another alternative conveyor.

[0008] Fig. 1 shows a conveyor 1. The conveyor 1 has a helical conveying path 2, which runs about an upright central axis 3. Furthermore, the conveyor 1 has a frame 4 which comprises a central column 5, feet 6 and a helical guide trough 7. The feet 6 and the guide trough 7 are mounted to the column 5.

[0009] The conveyor 1 is provided with an endless conveying member, in this case a slat belt 8, which is driven by a motor and is guided along the guide trough 7. The slats of the slat belt 8 have a longitudinal direction in transverse direction of the conveying direction of the slat belt 8. The slats are mutually connected through a chain, for example a side-bow chain. The slat belt 8 follows the helical conveying path 2 in vertical direction and is guided back through reverse rollers 9 and 10 at the ends of the helical conveying path 2 via a return section 11 by the shortest path to the helical conveying path 2.

[0010] Each of the slats of the slat belt 8 is provided with a spherical projection 12 in its centreline, in this case at the centreline where the chain is located, as well. The upper sides of the projections 12 together form an upwardly directed supporting surface 13 for supporting a product. Figs. 1 and 2 show that the supporting surface 13 is located in a central portion of the conveying path 2, as seen in a plane in which the central axis 3 lies, or a radial plane with respect to the central axis 3. Products like piece goods G can be placed onto the conveying member 8 and can be supported and conveyed by the supporting surface 13. The supporting surface 13 can also be formed in alternative manners, for example without using the slats.

[0011] Figs. 3-6 show cross-sections of the conveyor 1 according to Fig. 2 at a product G which is on the conveying path. The figures show that the width of the supporting surface 13 in radial direction of the central axis 3 is much smaller than the distance between the central axis 3 and the supporting surface 13, for example smaller than 10% thereof: moreover the conveying path 2 is free from obstacles at opposite sides of the supporting surface 13 at the height level of the supporting surface 13.

[0012] If the supporting surface was formed by flat upper sides of the slats, a block-shaped product having a flat and rigid bottom would basically rest on the slat belt through only two diagonally opposite corners, more specifically the highest corner at the inner bend and the lowest corner at the outer bend of the helical conveying path 2. This is caused by the fact that the inclination at the inner bend is steeper than the inclination at the outer bend. In practice a product will seek a third supporting location, such that it can wobble or even turn over.

[0013] The narrow supporting surface 13 being formed by the spherical projections 12 in the conveyor as shown in Figs. 1-6 is approached by a line contact between the bottom of the product G and the supporting surface 13 in case of a block-shaped product G having a flat and rigid bottom. Since in this case there is a space between neighbouring projections 12 of the slats in the conveying direction, there will be a broken line as seen from above, in fact a series of point contacts on a curved line. If the line contact or the series of point contacts would form a straight line, there would not be a stable supporting capacity, but since there is a line contact with a curved line, an automatic support of at least three points which are not on a single straight line, is created.

[0014] Fig. 5 shows that in the radial plane with respect to the central axis 3 the flat bottom of the product G in the middle of the product G extends nearly horizontally. In the conveying direction the product G is angled with respect to the horizontal plane which angle almost equals the average inclination of the conveying path 2. The cross-sections in other radial planes, as shown in Figs. 3, 4 and 6, show that the bottom of the product G have deviating angles with respect to the frame 4 than in the cross-section according to Fig. 5. It is noted, that if cross-sections are drawn of planes which extend parallel to that as shown in Fig. 5, the orientation of the product G would be always the same in the drawings.

[0015] Figs. 3-6 make clear that if the slats in radial direction with respect to the central axis 3 at a distance from the supporting surface 13 would have an obstacle at the height level of the supporting surface 13, these obstacles would form an extra contact surface outside the approached line contact and the intended effect would be destroyed. Thus, basically in Figs. 3-6 the slats on which the projections 12 are applied have no function and for that reason they are depicted as dashed lines.

[0016] Figs. 2, 3, 4 and 6 illustrate that the lack of obstacles at opposite sides of the supporting surface 13 means that a block-shaped product which is wider than the supporting surface 13 and even wider than the slat belt 8, and having a length of 10-20% of the length of a single revolution of the helical conveying path, for example, or is supported by for example 5-10 slats, the dimensions of the slat belt 8 are such that the block-shaped product only contacts the supporting surface 13 and not the remainder of the slats outside the supporting surface 13.

[0017] Although the approximated curved line contacts can transport block-shaped products having a rigid bottom, in practice there will be a demand to avoid possible tilting of a product with respect to the line contact. This might occur, for example, in case of uneven weight distribution of the product G or placing the product G out of centre on the conveying path 2. In order to prevent a product from turning over, an alternative conveyor is provided with bearing surfaces 14, see Figs. 7-10. In this conveyor the bearing surfaces 14 are formed by upper sides of small blocks which are provided on the slats. Hence, the bearing surfaces 14 move together with the supporting surface 13. However, it is also conceivable that the bearing surfaces 14 have a fixed position on the frame 4. When the product G tends to tilt, the bearing surfaces 14 will catch the product G.

[0018] In the conveyor according to Figs. 7-10 the bearing surfaces 14 are directed upwardly and are located below the supporting surface 13, as seen in a plane which extends radially with respect to the central axis 3. In another alternative conveyor the bearing surfaces 14 are located at the inner bend and outer bend of the conveying path 2. This is shown in Figs. 11-14, in which the slats are also made narrower in order to illustrate that they do not have a function in this case. The bearing surface at the inner bend of the conveying path 2 is indicated by 15 in the figures and is directed outwardly with respect to the central axis 3. The bearing surface at the outer bend of the conveying path 2 is indicated by 16 in the figures and directed to the central axis 3. The bearing surfaces 15, 16 in this conveyor will specifically be applied for transporting relatively tall products. The bearing surfaces 15, 16 are located above the supporting surface 13 in this case, as seen in a plane which extends radially with respect to the central axis 3. Although the bearing surfaces 15, 16 are part of the frame 4 in this conveyor, it is also conceivable to lengthen the slats and to provide their ends with upright supports having bearing surfaces 15, 16 thereon.

[0019] Figs. 15-18 show an embodiment of a conveyor according to the invention. In this case the supporting surface is formed by slats each having a central portion 17 and two lateral portions 18. The lateral portions 18 of the supporting surface are located in radial direction with respect to the central axis 3 at opposite sides remote from the central portion 17. The lateral portions 18 are resiliently connected to the central portion 17 via the slats. In rest, as shown in Fig. 15 the lateral portions 18 may lie at a higher level than the central portion 17 as seen in a radial plane through the central axis 3. This means that in case of a rebound the product may also be supported by one of the lateral portions 18, as can be seen at the right side of Fig. 16 and the left side of Fig. 18, for example.

[0020] Preferably, the lateral portions 18 may rebound in vertical direction with respect to the central portion 17 by more than 10% of the pitch of the helical conveying path 2 as can be seen in a plane in which the central axis 3 lies.

[0021] The lateral portions may be all kinds of spring elements, such as gel-filled spring members.

[0022] Figs. 19-22 show still another conveyor. In this case the slats of the slat belt 8 are tiltable about the helical centreline of the slat belt 8, such that a twistable supporting surface can be obtained. The helical centreline lies close to the chain in the centre of the conveying path in this conveyor. Each of the slats has a flat upper side. In the cross-sections as shown in Figs. 19-22 it can be seen that the slats take a position which corresponds to the bottom of the block-shaped product G. In such a case neighbouring slats have different orientations with respect to the horizontal. Due to the helical conveying path this means that the supporting surface is twisted locally.

[0023] Figs. 23-26 show still another conveyor. In this case each of the slats has a flat upper side and the slats are bendable in vertical direction in order to obtain a twistable supporting surface. The slats are only fixed to the chain at the helical centreline. In the cross-sections as shown in Figs. 23-23, 24 and 26 show that the non-loaded parts of the slats do not rebound.

[0024] The invention is not limited to the embodiment described hereinbefore, which may be varied in different manners within the scope of claim 1.

Claims

1. A conveyor (1), comprising a helical conveying path (2) having an upright central axis (3), a frame (4) and an endless conveying member (8) in the form of a slat belt for transporting a product (G) through the conveying path (2) which conveying member (8) is displaceable with respect to the frame (4), wherein the conveying member (8) is provided with an upwardly directed supporting surface for supporting a product (G), wherein the supporting surface is formed by slats, wherein each of the slats is provided with a central portion (17) and lateral portions (18) which are located in radial direction with respect to the central axis (3) at opposite sides of the central portion (17), characterized in that the lateral portions (18) are resiliently connected to the central portion (17) via the slats, wherein in rest the lateral portions (18) may lie at a higher level than the central portion (17) as seen in a radial plane through the central axis (3) such that in case of a rebound the product (G) is also supported by one of the lateral portions (18), wherein the lateral portions (18) may rebound in vertical direction with respect to the central portion (17) by more than 10% of the pitch of the helical conveying path (2) as can be seen in a plane in which the central axis (3) lies, wherein the lateral portions are spring elements, such as gel-filled spring members.