The object of the invention is a device for barking logs an similar, which device includes - several support wheels mounted horizontally on suppor arms on both sides of the log which are arranged to tur at an angle in relation to the log in order to suppor the log on the feed line formed by the wheels and a rotation device to rotate at least one support wheel and thus also to rotate and transport the log, a steel element with blades mounted on bearings to be able to rotate and located between two support wheels in the direction of the log as well as its rotation devices and adjusting mechanisms to be placed onto the log in such a way that the rotational axis of the steel element is in an essentially vertical direction in relation to the feed line, - a frame to support the support arms and steel elements.

The invention is essentially connected with the manufacture of barked logs used in building.

In order to use a log for building it must be barked or machined before being applied as part of a building. Traditionally the bark has been removed by manual peeling, which is, however, being superceded on account of its difficulty and slowness. The advantage with this method has been that the method of working has kept the wood surface intact beneath the bark, and has not cut the timber fibres. A log of this type has been long-lived, whereas a machined or turned log that has been made into a rough log rots four times more rapidly than a traditional barked log. Up until now there have been no suitable machines for manufac¬ turing a traditional barked log, all mechanical processes in the handling of the log leading to disadvantageous results from the point of view of the surface structure of the log.

It is a known process to carry out the processing of the log by turning it to an even thickness at the same time as the holes required for the framework joints are made in the ends and the groove is made in the under part of the log. Industrial manufac-

ture of this kind certainly brings advantages due to large series and considerable machining, but at the cost of the afore¬ mentioned surface structure and the natural liveliness of a log building.

The preliminary methods of processing a log mechanically can be divided into mainly two groups, which are turned processing methods and methods based on cutter milling. Machines for turning a log are shown in the Finnish publication print 43116 and in Finnish patent application 850175. By means of turning the log is generally made into a geometrically perfectly dimensioned cylinder, or in the best cases a piece with a conical surface.

Machines based on a cutter are shown in the German application publication 2309940, in Swedish patent publication 318702, as well as in Norwegian patent publication 151075.

The device in accordance with this invention is in the arrangement of the blades related mainly to a barking machine known from Finnish patent 34842, the arrangement of blades of which is of the type referred to in the introduction. This machine is not, however, able to bark a log in such a way that it retains the dense timber surface beneath the bark. The machine produces short bark chips and its blade sinks so deeply into the wood that it cuts the timber fibres in the surface layer. The machine is apparently not intended for the production of logs as the surface finish left by it is otherwise rough.

The intention of this invention is to create a device applicable precisely to the manufacture of barked logs, the surface finish of which recalls that of manual peeling. In particular, by means of the machine it is wished to retain the unity and density of the timber surface beneath the bark. The characteristic features of a device in accordance with the invention are presented in the accompanying Patent Claims. From the point of view of the operation of a device in accordance with the invention it is essential that it makes long chips, which is an important sub- factor in the creation of a dense timber surface. Here an

important method is formed by the rounded or otherwise conve ends of the blades, when the method of working recalls to som extent peeling with a hand knife. A long chip begins and end gradually. On the other hand the controlled and firm holding o the log on flexible wheels independently of the blade element is important from the point of view of the operation of th device, in which case the operation of the blades can b sufficiently gentle. Most advantageously the blades are presse against the log by a suitable spring force.

Other advantageous forms of application of the invention and advantages of it appear in connection with the forms of ap¬ plication presented later.

In what follows the invention is illustrated by reference to the accompanying figures, which show one kind of device in accordance with the invention for removing the bark from a log by means of mechanical peeling.

Figure 1 shows a device intended for barking as applied in connection with a tractor. Figure 2 shows a cross-section of the device in Figure 1 without a tractor. Figure 3 shows the jointing arrangement of the blade element. Figure 4 shows a blade of the blade element in detail.

A device in accordance with the invention can be most advantageously constructed to be attached to the three-point coupling of a tractor and to be connected to the power-take-off and hydraulic feed of the tractor. The tractor thus forms a part of the operating device.

The device to be attached to the tractor is constructed on frame 17, which forms a base when the device is in operation. Sub-frame 2 is attached to it by means of joint 16, to which sub-frame several pairs of wheels are jointed on arms 7 and 9. The opposite wheels 8 and 4 in four pairs form a feed line, in which the log 1 is moved back and forward in order to bark it. The further out pairs of wheels 8 on a forked arm is located on

an extension arm 21, which extends telescopically inside the sub-frame 2. In the transportation position the device is not much wider that the tractor, whereas in the operating position the extension arms 21 can be drawn out, when the outer distances between the wheels 4 and 8 can be made sufficiently large when bearing in mind the processing of ordinary logs.

The counter-wheels 3 press on top of the log on the feed line, which together with the underside support wheels 4 and 8 create a firm grip on the log being machined.

The sub-frame 2 is centred on springs 15 from frame 17, but when placing the log 1 to be processed into the device, the feed line is able to tilt and turn slightly in order to ease feed. At the same time when processing long logs in the device unreasonable strains are not placed on the device when the sub-frame permits small degrees of tilt and turning.

The central pairs of support wheels 4 are rotated by means of motor 5. When the support arms 7 and 9 set the pairs of wheels at a slight angle a rotational movement is also given to the longitudinal transportation of the log, the direction of which can be changed either by altering the direction of rotation or by turning the direction of the pairs of wheels to the other side with the aid of cylinder 20. Similarly the direction of the counter-wheels 3 must then be turned to correspond.

Figure 2 shows the entirety of the accessory installed on a tractor. The counter members of the three-point coupling are marked with the reference numbers 42 and 41 and the power-take- off of the tractor is coupled by means of a split joint to the grooved end 43 of the axle 13 of the blade element 6. In addition to this the hydraulic connections of the device are coupled to the hydraulic feed, the connections operating the rotation motor 5 and the hydraulic operating cylinders, cylinders 20, among others.

The counter-wheel 3 is suspended by means of a jointed arm 10 on support arm 14, which is further jointed to the sub-frame 2.

This can be operated with the aid of hydraulic cylinder 15, when the counter-wheels 3 can be pressed against the log. In addition a hook 22 is located on the end of a telescopic extension of support arm 14, by means of which the handling of the log onto and off the device can be easily carried out.

The lower support wheels 8 and 4 are supported on both sides by means of arm 19 and the synchronization arm 18 attached to it, so that they can be operated simultaneously. A partially manual turning system can also be considered, because a change of transportation direction can also be achieved by changing the direction of rotation.

All operations are controlled by means of the hydraulic valve block 14. The blade element can rotate continuously, as its speed of rotation need not be very great. In that case the support arm 14 is used with the aid of cylinder 15 by means of control levers 441 - 444 in feeding and removing the log and the operating motor 5 of wheel 4 to rotate and transport the log as well as the hydraulic cylinder 20 of the turning device of the support arms 9 and the blade element movement cylinders (not shown) .

Figure 3 shows the attachment arrangement of the blade element in greater detail. The bearings of the blade element 6 are located on a support, which is carried by the turning base 23 by means of parallelogram arms 24, the base resting on sub-frame 2. By means of this arrangement the centre line of the log 1 lies at more or less the same height as the blade element, irrespective of its thickness. The blade element is pressed against the log by means of spring 25. In addition the system includes a hydraulic cylinder, by means of which the blade element is pulled clear of the log during the feeding and removal of the log.

From the point of view of the invention the arrangement of blades of the blade element 6 in accordance with Figure 4 is quite fundamental. The knife blades 11 have such a form that they have sheath-knife-like ends 12. By means of this there is

an essential difference in the operation of the device where compared to the aforementioned known barking machine. The device creates long chips and the finish made by the device recalls that of a surface barked by hand. In this embodiment there is four blades in the blade element 6.

A device in accordance with the invention can be adapted in many ways. Advantageously all the lower support wheels are set in a double fork, which is then jointed to the sub-frame. The drive can then be transmitted from one wheel to another by means of a simple chain drive in the same way as the synchronization of the turning of the wheels is simpler than before.