WO2010042037A1

WO2010042037A1 - Gripping device

Info

Publication number: WO2010042037A1
Application number: PCT/SE2009/051118
Authority: WO
Inventors: Einar Karlsson
Original assignee: Hultdin System AB
Current assignee: Hultdin System AB
Priority date: 2008-10-09
Filing date: 2009-10-07
Publication date: 2010-04-15
Anticipated expiration: 2011-04-09
Also published as: SE0850033A1; FI20115232A7; SE533593C2; FI20115232L

Abstract

A gripping device for handling timber, comprising a support (1), a first, outer gripping claw (7), which is pivotally connected to the support on a first pivot axis (9) and exhibits a free end, and a second, inner gripping claw (8), which is pivotally connected to the support (1) on a second pivot axis (10) and exhibits a free end, said gripping claws being arranged to act against each other and cooperate contactlessly when the grapple is closed by the gripping claws performing a pivotal movement about their respective pivot axis. According to the invention, each free end exhibits a tip (20, 30) which is displaced, in the transverse direction (T) of the gripping device, toward one side of the gripping device, said tips being adapted to meet during the pivotal movement in order to form a substantially wedge-shaped, open space (31) between the free ends, said space being adapted to be reduced during the further pivotal movements of the gripping claws, when the inner gripping claw passes inside of the outer gripping claw, and to become fully closed, when the free end of the inner gripping claw has passed inside of the outer gripping claw.

Description

Gripping device

The present invention relates to a gripping device for handling timber, comprising - a support, a first, outer gripping claw, which is pivotally connected to the support on a first pivot axis and exhibits a first free end, and a second, inner gripping claw, which is pivotally connected to the support on a second pivot axis and exhibits a second free end, said gripping claws being arranged to act against each other and cooperate contactlessly when the grapple is closed by the gripping claws performing a pivotal movement about their respective pivot axis.

The invention primarily relates to a gripping device in the form of a grapple for handling timber.

When an operator is to pick up individual round timber with a conventional grapple, which is necessary for example when timber is to be sorted by wood species, the operator has to manoeuvre the grapple so that its transverse direction coincides with the longitudinal direction of the timber, i.e. so that the free ends of the gripping claws are parallel with the longitudinal direction of the timber. If the free ends are not parallel with the timber when the gripping claws are closed, the timber runs the risk of being pinched between the free ends without being brought in between the gripping claws, in which case the operator has to put down the timber and take a new grip. In case the longitudinal direction of the round timber or log deviates from the horizontal plane, it is difficult, and in some cases even impossible, to pick up the log with a conventional grapple. Since a grapple normally hangs freely from a gripping arm and can only be rotated about its vertical axis, in such a case the operator has to first set the grapple swinging, and then to rapidly- lower the grapple at the moment when the grapple is parallel with the log, to enable the gripping claws to grip around the log. This is of course a difficult and time-consuming method.

Another well-known problem with conventional grapples is that the free ends risk bringing moss, rocks, soil etc. with them when the gripping claws are closed around timber being lifted from the ground. These contaminants can then cause damages during the subsequent handling of the timber, for example in sawmills.

The object of the present invention is to solve these problems and to produce a gripping device which exhibits good gripping performance, and which prevents undesired objects, such as moss, rocks and soil, from being brought in with the wood when the timber is gripped.

The gripping device according to the invention is characterized in that each free end exhibits a tip which is displaced, in the transverse direction of the gripping device, toward one side of the gripping device, said tips being adapted to meet during the pivotal movement in order to form at least one substantially wedge-shaped, open space between the free ends, said space being adapted to be reduced during the further pivotal movements of the gripping claws, when the inner gripping claw passes inside of the outer gripping claw, and to become fully closed, when the free end of the inner gripping claw has passed inside of the outer gripping claw.

By designing the free ends of the gripping device with asymmetrically arranged tips, the advantage is obtained that the operator does not have to align the gripping device so that its transverse direction coincides with the longitudinal direction of the round timber he is to pick up. The operator can easily manoeuvre the gripping device so that the tips get underneath the round timber, and when the gripping claws are closed, the diagonal edges of the free ends will together force any obliquely positioned round timber to align themselves in parallel with the transverse direction of the gripping device. The tips also make it easier to pick up timber from the ground without bringing moss, rocks, soil and other undesired objects therewith, since the free ends of the gripping claws lack longer, cooperating straight edges between which the undesired objects could get stuck.

The asymmetrically arranged tips also make it considerably easier to pick up round timber or logs, the longitudinal direction of which deviates from the horizontal plane. By rotating the gripping device so that the tips are directed towards the highest end of the log, the operator can easily lower the gripping claws around the log without having to set the gripping device swinging . In the following, the invention will be described more closely with reference to the drawings, in which

Figure 1 shows, in perspective, a gripping device according to a first embodiment of the invention.

Figures 2 and 3 show, in a side view and in a view from below, the gripping device of Figure 1 in a position when the gripping claws of the gripping device are fully open.

Figures 4 and 5 show, in a side view and in a view from below, the gripping device of Figure 1 in a position when the gripping claws meet during closing.

Figures 6 and 7 show, in a side view and in a view from below, the gripping device of Figure 1 in a position when the nip between the gripping claws has been closed.

Figures 8 and 9 show, in a side view and in a view from below, the gripping device of Figure 1 in a position when the gripping claws are fully closed.

Figures 10 and 11 show, in a perspective view and in a side view, respectively, a gripping device according to a second embodiment of the invention.

Figures 12 and 13 show, in a perspective view and in a side view, respectively, a gripping device according to a third embodiment of the invention.

In the following, a first embodiment of a gripping device 34 according to the invention, in the form of a grapple, will be described more closely with reference to Figures 1-9, said grapple being intended for handling of delimbed as well as undelimbed timber.

The grapple 34 is in a known way intended to be articulately mounted on a boom (not shown) of, for example, a forwarder, truck, or an excavator, or on a boom (not shown) of a stationary assembly, for example in a sawmill. The grapple 34 comprises a support 1. The support 1 comprises a connecting portion 2, by means of which the grapple 34 is adapted to be connected to said boom. The support 1 further comprises a first side portion 3 and a second side portion 4, which are fixedly connected to the connecting portion 2. Thus, the first side portion 3 defines a first side 5 of the grapple 34, and the second side portion 4 defines a second side 6 of the grapple 34.

The grapple 34 further comprises a first, outer gripping claw 7 and a second, inner gripping claw 8. The outer gripping claw 7 is pivotally connected to the support 1 on a first pivot axis 9, and the inrter gripping claw 8 is pivotally connected to the support 1 on a second pivot axis 10, said second pivot axis 10 being substantially parallel with the pivot axis 9.

Accordingly, the gripping claws 7, 8 are arranged to act against each other in that they, when closing the grapple 34, by means of hydraulic cylinders (not shown) are caused to perform a pivotal movement V (see Figure 2) about their respective pivot axis 9, 10, in order to grip timber (not shown) between themselves and the support 1, while the inner gripping claw 8 is caused to move inside of and within the outer gripping claw 7. Figures 2 and 3 show the grapple 34 in a maximally open position and Figures 8 and 9 show the grapple 34 in a fully closed position. Figures 4 and 5 show the grapple 34 in a semi-closed position, where the two gripping claws 7 and 8 meet in their pivotal movements V and are tangent to a vertical plane of the grapple 34.

The outer gripping claw 7 comprises a first side portion 11, a second side portion 12 being substantially parallel with the first side portion 11, and an end portion 13, interconnecting the side portions 11, 12. The side portions 11, 12 are elongated, curved and extend between an inner end 14, 15, where they are connected to the support 1 on said first pivot axis 9, and an outer end 16, 17, where the end portion 13 interconnects the side portions 11 and 12. Accordingly, the end portion 13 forms a free end 18 of the substantially claw-shaped outer gripping claw 7. Between the end portion 13 and the side portions 11 and 12, the gripping claw 7 presents an open space or opening 19.

In the same way as in the outer gripping claw 7, the inner gripping claw 8 comprises a first side portion 21, a second side portion 22 being substantially parallel with the first side portion 21, and an end portion 23, interconnecting the side portions 21, 22. The side portions 21, 22 are elongated, curved and extend between an inner end 24, 25, where they are connected to the support 1 on said first pivot axis 10, and an outer end 26, 27, where the end portion 23 interconnects the side portions 21 and 22. Accordingly, the end portion 23 forms a free end 28 of the substantially claw-shaped inner gripping claw 8. Between the end portion 23 and the side portions 21 and 22, the gripping claw 7 presents an open space or opening 29.

In the gripping claws 7, 8, the substantially parallel side portions 11 and 12, and 21 and 22, respectively, are substantially perpendicular to the substantially parallel pivot axes 9 and 10. Accordingly, the gripping claws 7, 8 have a common transverse direction T_, which coincides with the common longitudinal direction of the pivot axes 9, 10. Thus, the gripping claws 7, 8 each have a predetermined width, i.e. a predetermined extension length in the transverse direction T_, which is determined by the distance between the side portions 11 and 12, and 21 and 22, respectively. In order to enable a closing pivotal movement V, where the inner gripping claw 8 moves within the outer gripping claw 7, the inner gripping claw 8 has a width which is slightly smaller than the width of the outer gripping claw 7.

In each gripping claw 7, 8, the free end 18, 28 has an extension length in the pivoting direction V of the gripping claw 7, 8 which increases substantially the entire distance from the second side portion 12, 22 to the first side portion 11, 21. Accordingly, each free end 18, 28 exhibits a tip 20, 30 which is displaced, in the transverse direction T of the gripping claw 7, 8, toward the first side portion 11, 21. During the pivotal movements V of the gripping claws 7, 8, the tips 20 and 30 move substantially in the same plane. Thus, during the pivotal movement V, the tips 20, 30 meet in said semi-closed position (see Figures 4 and 5) . In this position, a substantially wedge-shaped, open space 31 is formed between the edges 32 and 33 of the free ends 18, 28, said open space being reduced during the further pivotal movements V of the gripping claws 7, 8, in order to become fully closed when the gripping claws 7, 8 reach a predetermined second position, which is shown in Figures 6 and 7, where the inner gripping claw 8 has pivoted inward underneath the outer gripping claw 7.

By designing the free ends 18, 28 with tips, a grapple exhibiting very good gripping performance is obtained. In a conventional grapple, where the free ends are straight and parallel, the operator of the grapple has to manoeuvre the grapple, when he is to pick up timber, so that the free ends are parallel with the longitudinal direction of the timber. With a grapple 34 according to the invention, however, the operator can easily bring the tips 20, 30 underneath the timber also when the transverse direction of the grapple 34 is not parallel with the longitudinal direction of the timber. By means of the diagonal edges 32, 33 of the free ends 18, 28, any obliquely positioned timber will be forced to align themselves in parallel with the transverse direction of the grapple 34 when the gripping claws are closed.

Thanks to the diagonally positioned free ends, the advantage is also obtained that the grapple 34 according to the invention can be made wider than a corresponding conventional grapple. The wider a conventional grapple is, the greater will be the requirements for the free ends of the grapple to be parallel with the timber the grapple is to pick up. If a wide conventional grapple is not aligned in parallel with the timber, there is a large risk that the timber is jammed between the free ends when the grapple is closed, which forces the operator of the grapple to release the timber and align the free ends of the grapple in parallel with the timber before he takes a new grip. Since the grapple 34 according to the invention does not have to be aligned exactly in parallel with the timber before the gripping claws are closed, the grapple 34 according to the invention can instead be made wider than a corresponding conventional grapple. The larger width is an advantage, since the risk of a so-called brush or fan formation, where the gripped timber extend in different directions, is reduced the wider the grapple is .

By means of the tips 20, 30, undesired objects, such as moss, branches and logs causing brush-formations, will be pushed out in the transverse direction T_ from the nip formed between the gripping claws 7, 8. In order to enable the surface of the timber to slide along the edges 32, 33 when the gripping claws 7, 8 are closed, it is preferred that the edges 32 and 33 are straight and without any notches or other irregularities. Alternatively, the edges 32 and 33 can be concave or convex. In order to cause the timber to efficiently align themselves in the transverse direction of the grapple 34 when the gripping claws 7, 8 are closed, it is furthermore preferred that the free ends 18, 28 are so designed that the opening angle α of the wedge-shaped, open space 31 is at least about 18° and more preferably at least about 30°. However, the opening angle α should not be larger than about 140°, and more preferably not larger than about 120°. Furthermore, the asymmetrical positioning of the tips 20, 30 facilitates pick-up of non-horizontal logs, i.e. picking up logs the longitudinal direction of which deviates from the horizontal plane. By pivoting the grapple 34 so that the side 5 where the tips 20, 30 are arranged faces toward the highest end of the log, the operator can easily lower the gripping claws around the log.

Figures 10 and 11 show a second embodiment of a gripping device 35 according to the invention. Also this gripping device 35 has the form of a grapple for handling delimbed and undelimbed timber. The grapple 35 is substantially similar to the grapple 34 described above, but the grapple 35 comprises gripping claws 36, 37 exhibiting free ends 38, 39 the tips 40, 41 of which, as seen in the transverse direction T_ of the grapple 35, are arranged at distance of about 1/3 of the width of the grapple 35 from the first side portions 42, 43 of the gripping claws 36, 37. Accordingly, the tips 40, 41 are positioned between one side of the grapple 35 and the central plane of the grapple, i.e. the plane which extends half way between the first side portions 42, 43 of the gripping claws 36, 37 and their second side portions 44, 45, and which is perpendicular to the pivot axes 46, 47 of the gripping claws 36, 37. In Figure 11, this central plane is indicated with a dashed line 48.

By means of the positioning of the tips 40, 41 between one side of the grapple 35 and the central plane 48 thereof, the tips 40, 41 meet during a closing pivotal movement of the gripping claws 36, 37, while forming a first, larger, wedge-shaped open space 49 and a second, smaller, wedge-shaped, open space 50. These spaces 49, 50 are reduced during the further closing pivotal movements of the gripping claws 36, 37, to finally become fully closed. As in the grapple 34, it is preferred that the free ends 38, 39 are so designed that the opening angle α of the first space 49 is at least about 18°, and more preferably at least about 30°. However, the opening angle α should not be larger than about 140°, and more preferably no larger than about 120°. Preferably, the opening angle J3 of the second space 50 is equally large as the opening angle α of the first space 49, but alternatively J3 can be smaller or larger than α.

The above-mentioned advantages associated with the grapple 34, where the tips 20, 30 are positioned at one side of the grapple 34, are also obtained with the grapple 35, where the tips 40, 41 are positioned between one side of the grapple 35 and the central plane 48 of the grapple 35.

However, as regards the ability to pick up logs the longitudinal direction of which deviates from the horizontal plane, it has been found that a central positioning of the tips, i.e. a positioning of the tips in the central plane of the grapple, is less suitable. Accordingly, in the grapple according to the invention, the tips should be asymmetrically positioned. As used herein, asymmetrical positioning means than the tips are positioned at one side of the grapple, or between one side of the grapple and the central plane of the grapple. In other words, an asymmetrical positioning of tips implies that the tips are displaced, in the transverse direction of the gripping device, toward one side of the gripping device.

Trials have also shown that it is preferred that the tips move in the same pivot plane when the gripping claws perform their pivotal movements. However, a certain displacement of the tips in the transverse direction T of the grapple can be accepted, so that the tips instead move in two parallel, adjacent pivot planes. Preferably, however, the distance A between the pivot planes of the tips, which in Figure 11 have been indicated with reference numerals 51 and 52, should not exceed 10 cm, and more preferably this distance should not exceed 5 cm. However, in all circumstances, the pivot planes 51 and 52 should never be on different sides of the central plane 48.

Irrespectively of where the tips 20, 30, 40, 41 are positioned, they should be rounded and exhibit such dimensions that the timber is not pierced by and gets stuck on the tips 20, 30, 40, 41 when the grapple 34, 35 is closed. Each tip 20, 30, 40, 41 should, for example, preferably exhibit a radius of curvature, as seen in the plane of the free end 18, 28, 54, 55, which exceeds 20 mm.

Figures 12 and 13 show another embodiment of a gripping device 53 according to the invention. Also this gripping device 53 has the form of a grapple for handling delimbed and undelimbed timber. The grapple 53 is substantially similar to the grapple 34 described above in that it comprises gripping claws 54, 55 exhibiting free ends 56, 57, where each free end 56, 57 exhibits a tip 58, 59 which, as seen in the transverse direction T of the grapple 53, is displaced toward the first side portion 60, 61 of the gripping claw 54, 55. In this case, however, each tip 58, 59 exhibits a planar portion 62, 63, which extends a predetermined distance in the transverse direction T_ of the grapple 53. The planar portions 62, 63 are substantially parallel with the pivot axes 64, 65 of the gripping claws and, accordingly, the portions 62, 63 are also substantially parallel with each other. Preferably, each planar portion has an extension which is about 10-40% of the width of the grapple 53. In the shown embodiment, each planar portion 62, 63 has an extension which is about 20-30% of the width of the grapple 53, which is more preferred. However, in all circumstances, the planar portions 62, 63 should not be longer than half of the width of the gripping claw 53.

Also in the grapple 53, it is preferred that the open, wedge-shaped space 66, which is formed between the free ends 56 and 56 during the closing pivotal movements of the gripping claws 54, 55, exhibits an opening angle α which is at least about 18° and more preferably at least about 30°. However, the opening angle α should not be larger than about 140°, and more preferably no larger than about 120°.

As in the grapple 34, each gripping claw 36; 37 of the grapple 35 exhibits an open space or opening 67; 68 (see Figure 10) between the end portion 69; 70, first side portion 42; 43 and second side portion 44; 45 of the gripping claw 36; 37. In the same way, each gripping claw 54; 55 of the grapple 53 exhibits an open space or opening 71; 72 (see Figure 12) between the end portion 73; 74, first side portion 60; 61 and second side portion 75; 76 of the gripping claw 54; 55. Trials have shown that undesired material, such as, for example, rocks, moss, loose branches and other smaller objects accidentally brought in by the gripping claws when the grapple is closed, exits the grapple through these openings 19, 29, 67, 68, 71, 72 to a large extent. Accordingly, the openings 19, 29, 67, 68, 71, 72 allow a self-cleaning action of the grapple. Preferably, the openings should have as large an area as possible.

Accordingly, it is preferred that the width B of the end portions 13, 23; 69, 70; 73, 74 of the gripping claws 7, 8; 36, 37; 54, 55 is as small as possible, however, on the condition of maintaining the required structural integrity of the end portion.

In the foregoing, the invention has been described starting from a number of specific embodiments. It is appreciated, however, that other embodiments or variants are encompassed within the scope of the invention. For instance, it is appreciated that the free ends do not necessarily have to be straight. Alternatively, they can be concave or convex in the longitudinal direction of the respective free end.

Claims

C L A I M S

1. A gripping device (34, 35, 53) for handling timber, comprising - a support (1) , a first, outer gripping claw (7, 36, 54), which is pivotally connected to the support (1) on a first pivot axis (9, 46, 64) and exhibits a first free end (18, 38, 56), and - a second, inner gripping claw (8, 37, 55), which is pivotally connected to the support (1) on a second pivot axis (10, 47, 65) and exhibits a second free end (28, 39, 57), said gripping claws (7, 8, 36, 37, 54, 56) being arranged to act against each other and cooperate contactlessly when the grapple is closed by the gripping claws (7, 8, 36, 37, 54, 56) performing a pivotal movement (V) about their respective pivot axis (9, 10, 46, 47, 64, 65), characterized in that each free end (18, 28, 38, 39, 56, 57) exhibits a tip (20, 30, 40, 41, 58, 59) which is displaced, in the transverse direction (Tj of the gripping device (34, 35, 53), toward one side (5) of the gripping device (34, 35, 53), said tips (20, 30, 40, 41, 58, 59) being adapted to meet during the pivotal movement (V) in order to form at least one substantially wedge-shaped, open space (31, 49, 50, 66) between the free ends (18, 28, 38, 39, 56, 57), said space (31, 49, 50, 66) being adapted to be reduced during the further pivotal movements (V) of the gripping claws (7, 8, 36, 37, 54, 56), when the inner gripping claw (8, 37, 55) passes inside of the outer gripping claw (7, 36, 54), and to become fully closed, when the free end (28, 39, 57) of the inner gripping claw (8, 37, 55) has passed inside of the outer gripping claw (7, 36, 54) .

2. The gripping device (34, 53) according to claim 1, characterized in that the tips (20, 30, 58, 59) are arranged at one side (5) of the gripping device (34, 53) .

3. The gripping device (35) according to claim 1, characterized in that the tips (40, 41) are arranged between one side of the gripping device (35) and the central plane (48) of the gripping device (35) .

4. The gripping device (34, 53) according to any one of the claims 1-3, characterized in that the tips (20, 30, 58, 59) are arranged to move in substantially the same pivot plane.

5. The gripping device (35) according to any one of the claims 1-3, characterized in that each of the tips (40, 41) are arranged to move in a pivot plane (51, 52) of its own, said pivot planes (51, 52) being parallel with each other and arranged at distance from each other which does not exceed 10 cm.

6. The gripping device according to any one of the claims 1-5, characterized in that each free end (18, 28, 38, 39, 56, 57) exhibits an edge (32, 33), which is straight, wherein the open space (31, 49, 50, 66) forms a straight wedge, having an opening angle (α) within the interval 18°-140°.

7. The gripping device according to claim 6, characterized in that the opening angle (α) is within the interval 30°-120°.

8. The gripping device according to any one of the claims 1-5, characterized in that each free end exhibits an edge, which is concave in the longitudinal direction of the end.

9. The gripping device according to any one of the claims 1-5, characterized in that each free end exhibits an edge, which is convex in the longitudinal direction of the end.

10. The gripping device according to any one of the claims 6-9, characterized in that the edges (32, 33) are smooth.

11. The gripping device (34, 35, 53) according to any one of the claims 1-10, characterized in that each gripping claw (7, 8, 36, 37, 54, 56) comprises a first side portion (11, 21, 42, 43, 60, 61), which is arranged at one side of the gripping claw, a second side portion (12, 22, 44, 45, 75, 76) , which is arranged at the other side of the gripping claw, and an end portion (13, 23,

69, 70, 73, 74), interconnecting the side portions, which forms the free end (18, 28, 38, 39, 56, 57) of the gripping claw (7, 8, 36, 37, 54, 56), said portions delimiting an opening (19, 29, 67, 68, 71, 72) between themselves, through which opening objects, accidentally- brought in by the gripping claws, can exit the gripping device .

12. The gripping device (53) according to any one of the claims 1-11, characterized in that each tip (58, 59) exhibits a planar portion (62, 63), which extends a predetermined distance in the transverse direction (T) of the gripping device (53) .

13. The gripping device (53) according to claim 12, characterized in that said predetermined distance is within the interval 10-40% of the width of the gripping device (53) .