US2904085A - Revolving bark-removing tools simultaneously biased by endless pressure-equalizing band - Google Patents

Description

Sept. 15, 1959 o. c. G. WENNBERG REVOLVING BARK-REMOVING TOOLS SIMULTANEOUSLY BIASED BY ENDLESS PRESSURE-EQUALIZING BAND 3 Sheets-Sheet 1 Filed June 15, 1956 IN V EN TOR. Owv CAEL Guar/w fl-w/valse Ja /N #7775 O. C. G. W OVING TO Sept. 15, 1959 ENNBERG 2,904,085

' OLS SIMULTANEOUSLY BIASED PRESSURE-EQUALIZING BAND Flled June 15 1956 3 Sheets-Sheet 2 INVENTOR. 0101/ (4/21. Gus-ray MAA/BEKG REVOLVING BARK-REM BY ENDLESS United States Patent REVOLVING BARK-REMOVING TOOLS SIMUL- TANEOUSLY BIASED BY ENDLESS PRESSURE- EQUALIZING BAND Olov Carl Gustav Wennberg, Karlstad, Sweden, assignor to General Engineering Company A.B., a corporation of Sweden Application June '15, 1956, Serial No. 591,738 Claims priority, application Sweden June 20, 1955 3 Claims. (Cl. 144-208) In barking machines of the drum type it is common practice to set the barking tools against the log to be barked, by means of resilient members adapted to actuate the barking tools individually. This arrangement is generally satisfactory in the barking of straight logs with a comparatively smooth surface, whereas logs, which are crooked and have large or small depressions or elevations on the surface thereof, become unevenly barked. Bark is thus left in the depressions, while the elevations are subjected to working pressures of so high an order that the Wood might become damaged. In connection with crooked logs, the various tools are loaded difierently, so that the tools located on the convex side of the log are subjected to greater forces than the tools which for the time being are caused to bear on the opposite side.

The present invention has for its object to obviate these drawbacks. This is made possible, above all, by an arrangernent distinguished by the feature that the resilient pressure on the log is provided by means of a pressure member common to two or more of the barking tools. Generally, the barking tools are uniformly distributed along the circumference of the barking drum, and the common pressure member causes the working pressure to be distributed alike on the various tools. It is also provided for through the invention that the same pressure is obtained at all barking tools, independently of whether the log is located at the center of the barking drum or not. If a crooked log moves past the barking tools, so that their engaging surfaces are moved more or less eccentrically, this does not affect the working pressure, which thus becomes alike on the various tools in spite of the displacement. Hereby, an improved barking quality and a more rapid and uniform feeding of the logs through the machine are obtained in turn.

The pressure member may be constructed in different ways to bring about the desired working pressure. It may be resilient in itself, holders for the barking tools being then clamped into the same. It is also possible to arrange the pressure member as a distributor of one or more resilient forces on the various barking tools actuating the same, so that the barking tools are actuated by resilient forces of the same magnitude. It is also possible to make the pressure member resilient in itself while simultaneously causing the same to be actuated by resilient forces. a

The contrivance is advantageously provided with adjusting devices, by means of which the effect of the pressure member may be varied.

Further features of the invention and advantages connected therewith will appear from the following description of a few forms of embodiment.

In the accompanying drawing, Fig. 1 is a diagrammatic representation of a barking machine in vertical projection and partly in section. Fig. 2 shows the barking drum with the barking tools viewed on line 2-2 in Fig. 1. Fig. 3 represents a vertical transverse section through a barking drum that corresponds to the drum shown in Fig. 1, but shows spring pressed rollers and an endless nonelastic band for equalizing working pressures of the barking tools;

Fig. 4 represents a fragmentary right-hand elevation of Fig. 1, but omits a tool-positioning mechanism, and shows a modification of the construction in Fig. 3, the endless band being elastic and its tension being varied by screwactuated pressure rollers;

Fig. 5 shows a centripetal view of a detail of Fig. 4;

Fig.6 shows, in a fragmentary vertical transverse section through the drum on the line 6-6 in Fig. 1, details of a log-actuated, tool-opening and band-tensioning device;

Fig. 7 shows a centripetal view of a detail of the arrangement of Fig. 6, but includes a planar ring that shifts axially of the drum in response to changes in log diameter; and

Fig. 8 is a part sectional plan view of the preferred embodiment of the machine including the tensioning means appearing in Fig. 4, the means shown in detail in Fig. 7 being removed to enable proper illustration of other details.

As will be found from the drawing, a barking drum 1 is rotatably mounted in a housing 2, which is secured to a foundation 3. The barking drum is rotated in the housing 2 in a manner known per se by means of driving members, such as a wedge belt 1a and a Wedge ring 1b (Figs. 1 and 4). Barking tools 5 are arranged on a radial flange or disk 4 on the barking drum 1. The barking tools are secured to, or are integral with, holders in the form of curved arms 6 (Fig 2.), which are keyed onto shafts 7 carried in bearings 8 (Fig. 1) on the disk 4. The shafts 7 extend through the disk 4 and carry, at the opposite side thereof, crank or tensioning arms 9, which are also keyed to the shafts 7. Studs or rollers 10, hereinafter called crank rollers, are secured to the ends of the crank arms 9, and extending over said rollers, is a pressure member which provides or mediates the working pressure to the barking tools.

In the embodiment shown in Fig. 3, the pressure member consists of an endless band 11' running over all of the crank rollers 10. The pressure is provided by means of springs 12 adapted to actuate rods 13, which are displaceably mounted in holders 14 on the disk 4. The rods 13 preferably extend radially and carry pressure rollers 15 on the inner ends thereof, said rollers bearing on the band 11', which is reeved alternately around the rollers 10 and 15. In the construction shown, there are eight springs and pressure rollers mounted in equiangular radial relation with respect to the axis of the drum, but obviously the number of said members may be greater or smaller.

In a modified construction according to Figs. 1, 4 and 6, an endless band 11 is conceived of as being resilient in itself and consisting of rubber, for example, in which case the springs 12 and the corresponding pressure rollers of Fig. 3 become unnecessary, the control of the resilient tension of the band 11 being obtained by adjusting devices consisting of screw spindles 16 threaded into nuts 17, which are secured in holders 18 on the disk 4 of the'barkingdrum. Rollers 19 are provided on the inner endsof the spindles 16, whieh'are preferably directed radially, said rollers being set against the band 11, and the outer ends of the spindles carry operating members, such as star wheels 20 (Fig. 5). By the spindles 16 being screwed in with the aid of the star wheels 20 the band 11 is brought under tension, the barking tools being thus set against the log with greater force.

Figs. 1, 6 and 7 show various means to facilitate opening of the barking tools according to the diameter of the log to be barked. Such opening of the tools is intended to take place automatically in response to changes in log diameter, and the means for this purpose is evidenced by a comparison between the figures just mentioned.

The tool-opening contrivance consists of feeling members arranged for cooperation with the log 21 on the feeding-in side of the machine, said feeling members comprisinga pair of rollers 22, for example, between which the log is intended to pass when fed into the machine. The rollers 22 are mounted on angular arms 23, which are in turn mounted on axles 25 in floor-stands 24 laterally of the path of the logs. Said angular arms are provided with intermeshing toothed segments 26, so that they will turn simultaneously and by the same amount about the axles 25. Link rods 28 are articulated to a projection on each of the angular arms and to a plate or ring 27, said link rods 28 forming a lever system together with the angular arms. The angular arms are journaled at the plate 27 on a common pin 29. The plate 27 is carried by brackets 30 secured to the housing 2 and by rods 31 secured to the plate 27 (only one bracket and rod being illustrated), said rods extending displaceably in said brackets and parallel to the axis of the barking drum. The plate or ring 27 extends concentrically about the barking drum 1 and forms a plane race for rollers 32, which are mounted in arms 33 splined onto shafts 34. These shafts are journalled in brackets 35 on the disk 4'of the barking drum and actuate rackand-pinion 'gearings. Each gearing consists of a pinion or gear wheel 36 splined onto the shaft 34 and meshing with a toothed rack 37, which is displaceably mounted at one side of the disk 4 in slide bearings 38 (Fig. 6). One end of the toothed rack 37 bears on a projection 39 on a lug 40, which is secured on the crank arm 9 attached to the shaft 7 of the barking arms 6.

The mode of operation of the tool-opening device is as follows: When a log 21 is fed into the machine (see the arrow 41 in Fig. 1), the fore end thereof strikes against the rollers 22, so that the angular arms 23 are swung outwardly from one another and displace the plate 27 to the left by means of the link rods 28, as shown by the arrow 42. The arms 33 carrying the rollers 32 are thus caused to turn the shafts 34, in a manner such that the toothed racks 37 will be displaced by the gear Wheels 36 in a clockwise direction in Fig. 6. The crank arms 9 and the shafts 7 are simultaneously turned by the toothed racks 37 in a clockwise direction in Fig. 6, whereby the arms 6 of the barking tools are swung outwardly and the barking members proper are separated so as to leave an entrance opening of just the right size for the log (Fig. 2). At this movement the band 11 running over the crank rollers on the crank arms 9 will be strained to a suitable initial value. The barking tools are then kept set against the log with a suitable pressure. The pressure may be controlled by means of the adjusting devices 1620.

The advantages of the resilient means described reside, above all, in its equalizing effect on the working pressure between the barking tools and the log subjected to barking. This effect sets in both in connection with local irregularities in the log surface and in connection with crooked portions of the log. With reference to Figs. 1-3 this may be explained in principle as follows:

For instance, if one of the barking tools 5 moves past an elevation on the log, it will be swung outwardly, and consequently the corresponding crank will also swing out, so that its crank roller is brought to a greater diameter. As a result of this the pressure member is tensioned, but the increase of the tension is distributed along the whole of its circumference and thus also to the other barking tools, so that the working pressures on them become alike.

If instead a crooked portion of the log having a constant diameter moves past the barking tools, the engaging ends of the same will be displaced from the concentric position relatively to the axis of rotation of the barking drum taken by said ends, as when passing a straight log portion, to an eccentric position. This, however, does not alter the tension in the pressure member, inasmuch as the crank rollers 10 are only caused to lie with their centers on a circle which has been displaced eccentrically relatively to that circle concentric to the axis of rotation of the drum which they take in the initial position, or when a straight log passes between the barking tools.

A result of the uniform distribution of the resilient forces on the various barking tools is that the operation of the machine becomes smooth and steady, and that during the feeding'of the log between the barking tools the latter will accurately follow the surface of the log.

A special advantage is that the arrangement may be readily supplemented so that the tension in the pressure member and thus the working pressure on the log can be controlled during the operation of the machine.

What I claim is:

1. In a barking machine a rotary drum through which a log to be barked passes axially, a plurality of axles supported by said drum to be rotated therewith, barking tools each keyed to one of said axles, crank arms each keyed to one of said axles, and an endless flexible band actuating a plurality of said crank arms in common to apply a resilient pressure to the tools.

2. In a barking machine, a rotary drum through which a log to be barked passes axially, a plurality of axles supported by said drum to be rotated therewith, barking tools each keyed to one of said axles, crank arms each keyed to one of said axles, and a pressure member actuating a plurality of said crank arms in common to apply a resilient pressure to'the tools, pressure rollers mounted on said drum between said crank arms, and the pressure member comprising an endless band reeved alternately around the crank arms and the pressure rollers.

3. A barking machine comprising a rotary drum through which a log to be barked passes axially, swingable barking tools entrained by the drum; crank arms or levers connected with said tools, said levers comprising first rollers or studs; an endless band, and adjusting devices mounted on the drum for varying the tension of said band, said adjusting devices comprising second rollers, and the band being reeved alternately around said first and second rollers. 7

References Cited in the file of this patent UNITED STATES PATENTS 70,288 Swan Oct. 29, 1867 944,290 Spaak Dec. 28, 1909 2,749,952 Leagug June 12, 1956 2,767,750 Stewart Oct. 23, 1956 2,779,363 Laughton Jan. 29, 1957 2,786,499 7 I Brundell et a1. Mar. 26, 1957

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