GB2056908A - A feed and delivery of logs between two saws - Google Patents

Abstract

One band saw 16 is mounted on a fixed table 12 which is provided with a guide 10, and the second band saw 17 is mounted on a movable table 13 which is associated with a guide 14. A drive chain 15, having hooks 14 is located between the saws to drive logs 19 into the cutting zone, there being a self centering arrangement to ensure that the drive chain 15 is always centrally located between the cutting regions of the two band saws 16, 17. <IMAGE>

Description

SPECIFICATION Improvements in or relating to feed and delivery arrangement This invention relates to a feed and delivery arrangement, and more particularly to a log feed and delivery arrangement having two saws placed face to face, preferably band saws.

It is known to edge and slab logs in two parallel planes by means of arrangements comprising two band saws placed face to face and a table for feeding the logs to be edged and for subsequently receiving and delivering them, free from their side cuts, to be later cut into boards. In such a known arrangement the table is traversed, perpendicularly to the plane of operation of the said saws, by a horizontal endless chain, which feeds and drags the logs by means of a central push hook which presses on the rear end of each log. The chain runs between two guides parallel to the chain and consequently, perpendicular to the saw cutting line, and the chain is driven by a variable speed motor.

In all prior proposed arrangements of this kind the central feed chain is fixed in position and the two saws are simultaneously and symmetrically slidable towards and away from each other to enable their position to be adjusted to permit the thickness of the slabbed log to be adjusted having regard to the log diameter and to facilitate the subsequent cutting of the log into boards. The different cutting height at either side of a log, when the saws contact the log at different heights above the table, may create a very uneven moment which may tend to rotate the log from side to side, the cutting planes defined by the saws thus being moved out of parallelism. In some prior proposed arrangements the top side of the log is held by means of costly devices in an attempt to overcome this problem, but such prior arrangements are not totally successful.

The present invention seeks to provide a feeding and delivery arrangement in which the said disadvantages of prior arrangements are obviated or reduced.

According to this invention there is provided a feed and delivery arrangement for feeding logs to be edged and slabbed to a double saw having cutting elements placed face to face in the same plane, comprising a supporting base, a first table fixedly mounted on the base, and a second table mounted on the base for movement towards and away from said first table, two saws, mounted in respective predetermined positions relative to said two tables, with one saw thus being fixed in position and the other saw being movable, and an endless chain provided with at least one push hook arranged between the saws for feeding and dragging the logs to be edged between the saws, said chain being flanked by two longitudinal guides for supporting the logs, each of the said guides being securely mounted on a respective one of said tables, and located adjacent and parallel to the corresponding saw sawing plane and at a minimal distance therefrom, the chain and its push hook being displaceably mounted to move in the same direction as the movement of the second table, therebeing means to control this displacement of the chain and push hook so that the chain and push hook are always centred between the two saws.

Preferably said control means comprises a rotatable toothed wheel mounted on a housing for the chain and having a shaft parallel to the axis of the chain, and engaging, at its upper and lower sections, with respective toothed regions of two horizontal shafts, per pendicuiar to the wheel shaft, the two horizontal shafts being respectively to the first and second tables.

Conveniently a plurality of said toothed wheels are provided, each cooperating with respective horizontal shafts, the toothed wheels being securely mounted on a single common shaft.

Said saws may be band saws.

In preferred embodiments of the invention there are two guides for supporting and leading the log, both of them fixed in position with a respective one of the said saws and placed at a very small, constant distance from the cutting plane thereof.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a rear view of a feed and delivery arrangement according to the invention showing the guide, feed chain and sawing blade arrangement for the processing of a big log and, in dotted lines, the respective positions for the processing of a small log:: Figure 2 is a side elevation of the arrangement of Fig. 1 showing the relative position of the feed table and the delivery table with their respective guides and band saw blades; Figure 3 is a plan view of the arrangement of Fig. 1 showing the feed and delivery tables and the corresponding guides; Figure 4 shows in detail and at an enlarged scale, the relative positions of the various components of the double band saw for the edging of various diameter logs, and Figure 5 shows graphically and schematically the inconveniences arising from the use of the prior art double band saws.

Like references apply to like parts throughout the drawings.

Referring particularly to Fig. 1 a main supporting base 1 supports a stationary table 12 and a vertical column 2. A band saw 16 is mounted on wheels which are mounted on the base 1 and on the column 2. The band saw can rotate but the position of the band saw cannot be adjusted. The base 1 additionally supports a displaceable table 1 3 which is securely connected to a second column 4. A second band saw 1 7 is mounted on wheels which are movable with the table 1 3 and associated column 4. The outer part 3 of the movable table 1 3 is connected with a hydraulic piston 5 for effecting the displacement of the table and the associated column and second band saw towards and away from the first band saw.

Both of said tables are provided with a respective longitudinal guide 10, 11 formed integrally therewith for supporting a log, each guide being placed at a minimal distance from the sawing plane of the corresponding saw.

An endless feed chain 1 5 provided with hooks 1 4 for pushing logs is provided between said guides, the feed chain being operable to drive logs between the cutting portions of the two band saws.

A housing 6 along which said chain runs in the direction indicated by the arrows in Figs.

2 and 3 houses a self-centering gear. The selfcentering gear is associated with a lower shaft formed integrally with the stationary table 1 2 and having in its centre part a toothed upper surface which engages with a free running gear wheel 8 mounted on a fixed shaft within the housing 6. An upper shaft 9, corresponding to the shaft 7, is formed integrally with the table 8 and has a toothed lower surface which engages with the free running gear wheel 8. The housing 6 together with the associated chain 15, is movable in a horizontal direction perpendicular to the axis of the chains.

The above described arrangement is such that the centre of gear 8 and consequently, the centre of the housing 6 is maintained in a central position equi-distant from both saw blades as the saw blades are moved towards and away from each other. It is to be appreciated that, as shown in Fig. 2, three or more self-centering housings 6 are provided along the length of the chain the gears 8 of the housings being securely connected with each other by means of a connection shaft.Thus it is possible to displace the movable table 1 3 and the chain 1 5 so that the table 1 3 and the chain 1 5 are always exactly parallel to the stationary table 1 2. Thus the guide 11 integral with said table 1 3 will aiso be displaced parallel to guide 10 which is integral with the table 12.

Each housing 6 together with the gear 8 and the chain 1 5 will in turn be moved from said table 1 2 by half the distance covered by the table 1 3 in its displacement, thus remaining equidistant from both saws and the guides 10 and 11.

As can be easily understood, the constant presence of the guides 10 and 11 adjacent and very close to the sawing planes of the saws 1 6 and 1 7 prevents the log from turning even if it is subjected to an uneven moment that might be caused by the different cutting heights. With reference to Figs. 2 and 3 rollers 25 can be seen which are intended for the centering of the logs, by a known method, together with rollers 21 intended for the separation of the side cuts, also by a known method.In Figs. 1 and 4 two different diameter logs 1 9 and 20 are shown which are subject to the edging operation, and the different positions of the band saw 16, 1 7, the guides 10, 11 and of the chain 1 5 with its hook 1 4 resulting from the above described relative displacement are shown, with the second position being shown in dotted lines.

The reference numbers 24, 30 and 31 respectively identify a hydraulic power supply, the band saw driving motors and the driving motor for the chain 15, the latter being mounted on one of the housings 6.

As already mentioned, Fig. 5 schematically shows the prior art known arrangement, the chain 1 5 and the guies 10, 11 being stationary and the band saws 16, 1 7 being synchronously and simultaneously displaceable.

Claims (6)

1. A feed and delivery arrangement for feeding logs to be edged and slabbed to a double saw having cutting elements placed face to face in the same plane, comprising a supporting base, a first table fixedly mounted on the base, and a second table mounted on the base for movement towards and away from said first table, two saws, mounted in respective predetermined positions relative to said two tables, with one saw thus being fixed in position and the other saw being movable, and an endless chain provided with at least one push hook arranged between the saws for feeding and dragging the logs to be edged between the saws, said chain being flanked by two longitudinal guides for supporting the logs, each of the said guides being securely mounted on a respective one of said tables, and located adjacent and parallel to the corresponding saw sawing plane and at a minimal distance therefrom, the chain and its push hook being displaceably mounted to move in the same direction as the movement of the second table, there being means to control this displacement of the chain and push hook so that the chain and push hook are always centred between the two saws.

2. An arrangement according to claim, wherein said control means comprises a rotatable toothed wheel mounted on a housing for the chain and having a shaft parallel to the axis of the chain and having a shaft parallel to the axis of the chain, and engaging, at its upper and lower sections, with respective toothed regions of two horizontal shafts, per pendicular to the wheel shaft, the two horizon tal shaft being securely connection respectively to the first and second tables.

3. An arrangement according to claim 2, wherein a plurality of said toothed wheels are provided, each cooperating with respective horizontal shafts, the toothed wheels being securely mounted on a single common shaft.

4. An arrangement according to any one of the preceding claims wherein said saws are band saws.

5. A feed and delivery arrangement substantially as herein described with reference to and as shown in the accompanying drawings.

6. Any novel feature or combination of features disclosed herein.