US3756296A

US3756296A - Device for feeding logs through a processing machine

Info

Publication number: US3756296A
Application number: US00186309A
Authority: US
Inventors: B Ackerfeldt
Original assignee: Natural Resources Inc
Current assignee: Natural Resources Inc
Priority date: 1971-10-04
Filing date: 1971-10-04
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04

Abstract

An apparatus for feeding logs, blocks or similar elongate objects through one or several successive saws or other processing machines in a wood-processing mill includes a pair of vertically extending log-holding arms supported by and movable along an overhead trackway extending parallel to the desired feeding line for the logs. The log-holding arms have a loggrasping means at their lower ends adapted to grasp and hold the opposite ends of the log while moving the log along the feeding line. Each log-grasping means comprises a clamping device which clamps an end of the log from above and below. The clamping device includes a lower, horizontally projecting clamping member fixed to its arm and upon which a lower circumferential undersurface portion of the log end rests. The device further includes an upper clamping member moved along the arm by a cylinder into clamping engagement with an upper circumferential surface portion of the end of the log, thereby clamping the log end from above and below securely between the upper and lower clamping members.

Description

Waite States Patent 1 Ackerfeldt 1 Sept. 4, 1973 1 DEVICE FOR FEEDING LOGS THROUGH A PROCESSING MACHINE [75] inventor: Bo Ingemar Ackerleldt, Ascona,

Switzerland [73] Assignee: U.S. Natural Resources, Inc.,

Portland, Oreg.

[22] Filed: Oct. 4, 1971 [21] Appl. No.: 186,309

[30] Foreign Application Priority Data Oct. 9, 1970 Sweden 7013717 [52] US. Cl 143/125, 143/117, 143/25 [51] Int. Cl 1327b 29/08 [58] Field of Search 143/125 R, 125 A,

143/25, 117, 105, 126 P, 126 A, 127, 128, 129, 130, 131, 54 A; 83/409 [56] References Cited UNITED STATES PATENTS 3,503,428 3/1970 Ackerfeldt 143/117 Primary ExaminerDonald R. Schran Attorney-Stephen W. Blore et a1.

[5 7 ABSTRACT An apparatus for feeding logs, blocks or similar elongate objects through one or several successive saws or other processing machines in a wood-processing mill includes a pair of vertically extending log-holding arms supported by and movable along an overhead trackway extending parallel to the desired feeding line for the logs. The log-holding arms have a log-grasping means at their lower ends adapted to grasp and hold the opposite ends of the log while moving the log along the feeding line. Each log-grasping means comprises a clamping device which clamps an end of the log from above and below. The clamping device includes a lower, horizontally projecting clamping member fixed to its arm and upon which a lower circumferential undersurface portion of the log end rests. The device further includes an upper clamping member moved along the arm by a cylinder into clamping engagement with an upper circumferential surface portion of the end of the log, thereby clamping the log end from above and below securely between the upper and lower clamping members.

13 Claims, 5 Drawing Figures PATENTEDSEP 1975 DEVICE FOR FEEDING LOGS THROUGH A PROCESSING MACHINE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is related to a device for feeding logs, cants, blocks or similar elongate objects through one or several successive saws or other processing machines. The device according to the invention is of the general type known in the prior art, which comprises substantially vertical logholding arms, which are supported by and movable along a trackway extending above the saw parallel to the desired feeding line for the logs and which are adapted to grasp and hold the end of a log at their lowermost ends while feeding the log along said feeding line. Generally each log is supported between two such logholding arms, which hold the log at its fore and rear ends respectively. Prior art feeding devices of this type are described, for instance, in the Swedish Pat. Nos. 301,868 and 306,162.

2. Description of the Prior Art A problem in'feeding devices of this type is to provide such a design of the lowermost ends of the logholding arms that they obtain a sufficiently firm grip of the ends of the logs to prevent any displacement of the log, in particular rotation of the log about its longitudinal axis, during the feeding and in particular the sawing or other processing of the log. This problem is made more difficult in that the log-holding arms must in most cases be able to pass together with the log between two processing tools, for instance, two saw blades, disposed side by side, wherefore the lateral extension of the logholding arm must be kept small at least at the lowermost end of the log-holding arm, where this cooperates with the end of the log.

Previously one has solved this problem by providing the lowermost end of the log-holding arms with a number of horizontally projecting spikes adapted to be pressed into the end surface of the log, whereby the log will be supported and kept in a fixed position by the log-holding arm. However, this solution is not entirely satisfactory. Thus, a reliable grip between the logholding arm and the end of the log requires obviously that the end surface of the log be substantially plane and perpendicular to the longitudinal axis of the log so that all spikes on the log-holding arm can be pressed into the end surface of the log. However, very often the end surface of the log is such that only those spikes closest to the center of the end surface will project into the end surface, giving a very unreliable grip, as these spikes are incapable of preventing rotation of the log about its longitudinal axis. Such a rotation of the log must, however, be prevented if accurate processing of the log, for instance sawing, is to be achieved. Further, a considerable axial force between the log-holding arm and the log is required if the spikes on the log-holding arm are to be pressed into the end surface of the log and kept in this position.

Therefore, with such prior devices it is necessary that the log be clamped firmly between two log-holding arms acting against the fore end surface and the rear end surface of the log respectively. It is not possible to hold the log, for example, only at its rear end with a single log-holding arm, while the fore end of the log is permitted to slide on a stationary support member that may be provided with guide grooves or similar arrangement for the guiding of the fore end of the log. Yet such a single-arm arrangement might otherwise be suitable at smaller sawmills adapted for a comparatively limited production.

Further, with such prior devices the necessary axial clamping force between the log and the log-holding arms must obviously be taken up by the log-holding arms and the coupling means between the log-holding arms and their drive means. Therefore these components and members of the prior devices must be heavily dimensioned in order to withstand these forces without undue strain.

SUMMARY OF THE INVENTION A primary object of the present invention is therefore to provide a feeding device of the general type mentioned in the foregoing, at which the above-discussed problems are solved in a satisfactory way. According to the invention this is achieved in a feeding device designed in accordance with the accompanying claims.

In a device according to the invention, a reliable grip between the log-holding arm and the end of the log, preventing any displacement or rotation of the log relatively to the log-holding arm, is achieved independent of the shape of the end surface of the log.

Further, in a device according to the invention, no or only a very small axial force is required between the log-holding arm and the log in order to achieve a reli able grip of the end of the log. Therefore, the invention can also be used in a feeding device, in which the log is gripped at one end only by only one log-holding arm. The single arm preferably grips the rear end of the log, whereas the opposite end of the log may rest upon and slide along a stationary support surface.

Further, in a device according to the invention, it is not necessary that the log-holding arm and associated members be dimensioned for any large axial clamping forces between the log-holding arm and the log.

BRIEF DESCRIPTION OF THE DRAWINGS In the following the invention will be further described with reference to the accompanying drawing, which illustrates by way of example an embodiment of a log-feeding device according to the invention. In the drawings:

FIG. 1 is a partial side view of a sawmill provided with a log-feeding device according to the invention;

FIG. 2 is a section through the sawmill in FIG. 1 taken along the line II-II in FIG. 1;

FIG. 3 is a side view on an enlarged scale of the lower portion of a log-holding arm;

FIG. 4 is a front view of the log-holding arm in FIG. 3 as seen from the line IV- -IV in FIG. 3; and

FIG. 5 is a section through the log-holding arm in FIG. 3 taken along the line V-V in FIG. 3.

The drawings show schematically a sawmill comprising a double band saw with two

saw blades

1 and 2. The feeding direction for thelogs through the saw is indicated with an arrow 3 in FIG. 1. The logs are fed through the saw by means of a feeding device, which to a large extent is designed in the same manner as the feeding device shown in FIGS. 1 to 4 in the Swedish Pat. No. 301,868 and which is described in detail in said patent.

Thus, the feeding device comprises a fore log-holding arm 4 and a rear log-holding'arm 5, which are mounted on two separate carriages 6 and 7 respectively. The carriages are supported by and movable along an overhead trackway 8 extending above the saw parallel to the desired feeding line or path for the logs through the saw from the input side to the output side of the saw. The log-holding arms 4 and 5 are pivoted in their associated carriages and can be moved by means of

hydraulic cylinders

9 and 10 respectively or similar actuating means between a vertical active position and a substantially horizontal inactive or return position. For driving the carriages 6 and 7 with the log-holding arms 4 and 5 an endless drive chain 11 is provided, which can be driven selectively in the one or the opposite direction. By the aid of suitable coupling means the carriages 6 and 7 for the log-holding arms 4 and 5 can be selectively connected to and disconnected from this drive chain 1 1, as described more in detail in the Swedish Pat. No. 301 ,868. For the carriage 6 of the fore log-holding arm 4 a spring-biased retainer pawl 12 with an associated release cam 13 is mounted on the trackway 8 at the input side of the saw in the manner described more in detail in the Swedish Pat. No. 30l,868.

In order to increase the production capacity the feeding device illustrated by way of example in the drawings is provided with an additional pair of log-holding arms designed in exactly the same manner as the log-holding arms 4 and 5 with their associated carriages 6 and 7. Of this additional pair of log-holding arms, however, only the rear log-holding arm 14 with its associate carriage 15 is shown in FIG. 1. As can be seen from FIG. 2, the trackway 8 for the carriages 6 and 7 of the log-holding arms 4 and 5 is disposed somewhat to the one side of the vertical plane containing the feeding line for the logs, whereas the trackway 16 for the carriage 15 of the additional rear log-holding arm 14 and for the carriage of the corresponding fore log-holding arm, not shown in the drawing, is disposed on the opposite side of said vertical plane. However, all log-holding arms are bent in such a way that they have their lowermost portions disposed in the vertical plane containing the feeding line for the logs. As can be seen in FIG. 2, this makes it possible for a carriage having its log-holding arm raised in the horizontal inactive or return position and a carriage having its log-holding arm lowered in the vertical active position to pass each other when moving in opposite directions. The carriage 15 of the rear logholding arm 14 and the carriage of the associated fore log-holding arm, not shown in the drawing, are driven either by means of a separate drive chain, corresponding to the drive chain 11, or by the same drive chain 11 as the carriages 6 and 7 for the log-holding arms 4 and 5 respectively. The pairs are driven in such a manner that when one pair of log-holding arms is moved in the feeding direction 3, the other pair is moved in the opposite return direction and vice versa. In this way the one pair of log-holding arms can feed a log through the saw at the same time as the second pair of log-holding arms is returned from the output side to the input side of the saw.

For holding the logs while feeding them though the saw, the lower end portions of the log-holding arms are of a special design incorporating a log end-clamping mechanism, as shown more in detail in FIGS. 3, 4 and 5 for the rear log-holding arm 5. At its lowermost end this clamping mechanism for log-holding arm 5 includes a lower clamping means in the form of a ledge of platform 17, which is rigidly attached to the logholding arm and which projects substantially horizontally therefrom in the feeding direction of the logs, The log-holding arm is additionally provided with an upper clamping means including a slide or runner 18, which is movable in vertical direction relative to the logholding arm 5 and lower clamping means, and is guided in a slot in the arm, as most readily seen in FIG. 5. This slide 18 is provided with a clamping arm 20, which projects in the feeding direction of the logs. The outer end of this clamping arm curves downwardly, as shown in FIG. 3.

The log-holding arm 5 carries also a clamp-inoving means comprising hydraulic or pneumatic cylinder 21 or a similar force-generating actuating means, which is coupled to slide 18. By this hydraulic cylinder 21, slide 18 and thus clamping arm 20 of the upper clamping means can be forced downwardly toward platform 17 of the lower clamping means. If, as illustrated in FIG. 3, the rear end of a log 22 is positioned in front of logholding arm 5, the arm 20 may by the hydraulic cylinder 21 be pressed downwards against the upper circumferential surface of the log 22 adjacent the rear end of the log, whereby the end of the log is pressed downwards against platform 17. Thus, the end of the log 22 is clamped between the arm 20 of the upper clamping means and the platform 17 of the lower clamping means.

In order to produce a better grip, the clamping arm 20 may be provided with downwardly pointing spikes 20a and the platform 17 may be provided with upwardly pointing spikes 17a. These are forced into the circumferential surface of the log 22 from above and below respectively, when the end of the log is clamped between clamping arm 20 and platfonn 17.

Instead of such spikes the platform 17 may, for instance, be provided with projecting sharp edges extending in the feeding direction. Similarly clamping arm 20 may be provided with similar downwardly facing sharp edges, also extending in the feeding direction. Such edges will effectively resist rotation of the log 22 about its longitudinal axis.

In the same manner the fore log-holding arm 4 is provided with a lower clamping means including platform 23 projecting backwards from the arm and an upper clamping means including clamping arm 24 also projecting backwards. A hydraulic cylinder 25 connected to arm 4 moves clamping arm 24.

The carriages for the log-holding arms are guided laterally by means of

guide rails

26 and 27 respectively, as shown in FIGS. 1 and 2. In their lowered vertical active position the lowermost ends of the log-holding arms are additionally guided laterally in a groove 28 provided in a guide rail 29 extending below the feeding line.

For receiving a log'22 to be fed through the saw, a number of fork-shaped

support members

30, 31 and 32 are provided at the input side of the saw. These support members can be pivoted between an upper and a lower position. Two or several suitably positioned such support members can be raised to their upper position for receiving and supporting a log 22 which has been supplied to the input side of the saw in any suitable manner, not illustrated in the drawing. A log 22 resting in these raised support members, for

instance

30 and 32 in FIG. 1, can be rotated about its longitudinal axis to a position suitable for the sawing of the log by means of rotating means 33, which in the illustrated embodiment of the invention consists of two endless chains dis- OPERATION When the log 22 supported in the raised

support members

30 and 32 has been rotated in'this manner to a desired position, the rear log-holding arm 5, which is in its vertical active position, is started by the drive chain 11 and so moves toward the rear end surface of the log 22, whereby the log is put into motion. As soon as the log 22 starts to move, the hydraulic cylinder 21 is activated in a suitable automatic way. forcing clamping arm downwardly against the upper circumferential surface of the log 22.

The carriage 6 of the fore log-holding arm 4 is disconnected from the drive chain 11 and thus is initially stationary and retained by the spring-biased pawl 12.

As the log 22 moves forward, however, the fore end surface of the log strikes the fore log-holding arm 4, whereby arm 4 moves forward together with its carriage 6 against the action of the spring-biased pawl 12. As soon as the fore log-holding arm 4 starts to move, the hydraulic cylinder is activated in any suitable automatic manner to force clampingarrn 24 downwardly against the upper surface of log 22 at the fore end of the log. During this process, support forks and 32 supporting the log 22 lower, whereby log 22 descends. The clamping

arms

20 and 24 follow the log in its downward motion while maintaining a downwardly directed force upon the log.-

When the ends of the log 22 reach the projecting fixed platforms l7 and 23 of the lower clamping means on the log-holding arms 5 and 4 respectively, the downward motion of log 22 ceases. Thus the rear end of the log'becomes clamped securely between platform 17 and the clamping arm 20 of the clamping mechanism on the rearlog-holding arm 5 by the force exerted by hydraulic cylinder 21. At the same time, the fore end of the log becomes clamped in the same manner between the platform 23 and the clamping arm 24 of the clamping mechanism on the fore log-holding arm 4 by the force exerted by the hydraulic cylinder 25. In this way the log 22 is held at both ends from above and below in a very firm grip, which effectively prevents any rotation of the log '22 about its longitudinal axis.

.When during the continued movement of the fore log-holding arm 4 in the feeding direction the retainer pawl 12 is released by the release cam 13, carriage 6 of the fore log-holding arm 4 is automatically connected to drive chain 11 in the manner described in Swedish Pat. No.- 301,868. As, obviously, no substantial axial clamping force is necessary between the log-holding arms 4 and 5 and the log 22 in order to hold the log 22 firmly in the log-holding arms, the biasing spring for the retainer pawl 12 may be comparatively weak. This reduces substantially the strain exerted upon log-holding arms 4 and 5 and their associated carriages 6 and 7, and

' in particular upon the coupling means between these carriages and the drive chain 1 1. Also the tension in the drive chain will be reduced correspondingly. Therefore all these components can be dimensioned for small strains, which reduces the weight and costs of these components and also the wear on them.

It should be noted that the invention is not restricted to the embodiment thereof illustrated in the drawings and described in the foregoing. Thus, the invention is applicable with the same advantages also in other types of log-feeding devices provided with vertical logholding arms adapted to hold only one end of a log while feeding the log through one or several processing machines. Thus, the invention may, for instance, be used with great advantage in a feeding device, in which the log is held only by one log-holding arm at its one end, preferably at its rear end, while the opposite end of the log slides along a stationary support surface. Such surface may be provided with guide grooves or guide edges extending in the feeding direction.

Having illustrated and described what is now a preferred embodiment of my invention and possible alternative embodiments, it should now be apparent that the invention permits of modification in arrangement and detail. I claim as my invention all such modifications as come within the true spirit and scope of the following claims.

I claim:

1. A device for feeding a log or a similar elongated object through a saw or similar wood-processing machine comprising:

at least one generally vertically extending log-holding arm means, an overhead trackway means extending above and parallel to the desired feeding path of the logs supporting said arm means for movement therealong,

said log-holding arm including at a lower portion thereof a log end clamping mechanism adapted to grasp and hold an end portion of a log,

said mechanism including a lower clamping means for supporting a circumferential undersurface portion of said, log and an upper clamping means spaced above said lower clamping means for clampingly engaging an upper circumferential surface portion of said log,

means mounting at least one of said upper and lower clamping means on said arm for movement in a vertical direction relative to the other said clampmg means,

and means operably connected to the movable one of said clamping means for moving said vmovable clamping means into clamping engagement with a circumferential surface portion of said log and for maintaining a clamping force between said upper and lower clamping means and said log.

2. A device according to claim 1 wherein one of said upper andlower clamping means is fixed to said logholding arm and the other of said upper and lower clamping means is movablevertically along said logholding arm.

3. A device according to claim ll wherein said lower clamping'means is fixed to said log-holding arm and said upper clamping means is movable vertically along .said log-holding arm.

ing one of said upper and lower clamping means comprising a force-generating means connected to said clamping arm for forcing it downwardly against an upper circumferential surface portion of the log at the end thereof, whereby the end of the log is clamped between said clamping arm and said support platform.

6. A device according to claim wherein said support platform is rigidly attached to said log-holding arm.

7. A device according to claim 5 wherein said support surface of said support platform is provided with one or several upwards pointing spikes adapted to penetrate the circumferential surface of the log.

8. A device according to claim 5 wherein said support surface of said support platform is provided with one or several projecting sharp edges extending substantially in the direction of the feeding line and adapted to penetrate the circumferential surface of the log.

9. A device according to claim 5 wherein said clamping arm is provided with one or several downwards pointing spikes adapted to penetrate the circumferential surface of the log.

10. A device according to claim 5 wherein said clamping arm is provided with one or several projecting sharp edges extending substantially in the direction of the feeding line and adapted to penetrate the circumferential surface of the log.

11. A device according to claim 5 wherein said clamping arm is mounted on a slide movable in a guide path in the log-holding arm.

12. A device according to claim 1 wherein the means for moving one or the other of said upper and lower clamping means includes a fluid-powered extensible cylinder means carried by said log-holding arm.

13. A device according to claim 1 wherein there are a pair of said log-holding arms, one for each of the opposite ends of a log or similar elongated object, each provided with one of said clamping mechanisms.

Claims

1. A device for feeding a log or a similar elongated object through a saw or similar wood-processing machine comprising: at least one generally vertically extending log-holding arm means, an overhead trackway means extending above and parallel to the desired feeding path of the logs supporting said arm means for movement therealong, said log-holding arm including at a lower portion thereof a log end clamping mechanism adapted to grasp and hold an end portion of a log, said mechanism including a lower clamping means for supporting a circumferential undersurface portion of said log and an upper clamping means spaced above said lower clamping means for clampingly engaging an upper circumferential surface portion of said log, means mounting at least one of said upper and lower clamping means on said arm for movement in a vertical direction relative to the other said clamping means, and means operably connected to the movable one of said clamping means for moving said movable clamping means into clamping engagement with a circumferential surface portion of said log and for maintaining a clamping force between said upper and lower clamping means and said log.

2. A device according to claim 1 wherein one of said upper and lower clamping means is fixed to said log-holding arm and the other of said upper and lower clamping means is movable vertically along said log-holding arm.

3. A device according to claim 1 wherein said lower clamping means is fixed to said log-holding arm and said upper clamping means is movable vertically along said log-holding arm.

4. A device according to claim 1 wherein said lower clamping means comprises a support platform projecting substantially horizontally in the direction of the feeding path towards the log and having a support surface for the end of the log.

5. A device according to claim 4 wherein said upper clamping means comprises a clamping arm above said support platform projecting substantially in the same direction as said support platform, said means for moving one of said upper and lower clamping means comprising a force-generating means connected to said clamping arm for forcing it downwardly against an upper circumferential surface portion of the log at the end thereof, whereby the end of the log is clamped between said clamping arm and said support platform.

6. A device according to claim 5 wherein said support platform is rigidly attached to said log-holding arm.