FI58883C - RAMSAOG MED PENDLANDE VEVPARTI - Google Patents

Description

ADVERTISEMENT „Λ A ä jJ®Tg ® (11) UTLÄOGNI NOSSKRIFT 5 8 8 8 3 • C Fstor.tti Dyännotty 11 05 1031

Patent meddelat ^ ^ (51) Kv.lk.3 / IntCI.3 g 27 B 3/12 SUOM I — FIN LAND pi) p «t« «cih ^ -N« itwiiaiii «i 131 + 6/73 (22) HakamlipUvi - Arattknlnfsdif 26.Ok. 73 ^ ^ (23) AlkupUvt — GlM | h «tadig 26. (Λ.7 3 (41) Interpreters | ulklMk * l - Bltvlt off« ntllg 03.11 * 73

Nt-ttl ·). rU.lrt-flh.lllt— mKM—

Patani och ragisterstyrdNIl '' ΑηΛΙαη uttagd och utUkrHtm ρυΜΙηπκΙ 30.01.01 (32) (33) (31) fyHtttjr «uolk * M» —B «glrd prioiitut 02.05.72

Sweden-Sweden (SE) 57 ^ 8/72 (71) Kockum Industri AB, Fack, 826 01 Söderhamn, Sweden-Sweden (SE) (72) Hjalmar Johansson, Sollentuna, Sweden-Sweden (SE) (7 * +) Berggren Oy Ab (5I +) Circular saw with oscillating crank - Ramsäg med pendlande vevparti

Circular saws are often used in the manufacture of sawn timber from saw logs or sawn supports. Today, the most common type of circumferential saw has a base anchored to the base, an upwardly and downwardly moving sawtooth in the pedestal to which a plurality of parallel saw blades and an actuator are tensioned, comprising a crankshaft and a connecting rod connected to the saw frame and moving it up and down in the pedestal.

Recent improvements to circular saws have only included discrete components such as saw blades, saw blades, and bearings. The basic structure has not been changed and the problems associated with the circular saw as a cause of strong vibrations continue to burden the existing circular saws, which therefore require a foundation for careful anchoring. The vibrations depend mainly on the fact that the movements of the saw ring and the connecting rod produce large vibrating forces which are transmitted to the base via the crankshaft.

The object of the invention in a circular saw of the above-mentioned type is to considerably dampen vibrations in the base. The main features of the invention appear from the appended claim 1.

58883 For this purpose, the crankshaft of a circular saw drive according to the invention is rotatably mounted on a cradle supported by a stand, reciprocating relative to the base in a substantially horizontal direction, perpendicular to the crankshaft, by the forces exerted by the crankshaft as it rotates.

Thus, since the crankshaft has the freedom to move horizontally in its transverse direction, it will, when rotating, perform a periodic horizontal displacement at a frequency equal to the frequency of the reciprocating motion of the saw ring. This displacement is so phase-shifted with respect to the movement of the saw ring that the crankshaft is in its intermediate position> when the saw ring is in its end positions and that the crankshaft is in its end positions when the saw ring is in its middle position. When the crankshaft is free to move in this way, a considerable reduction in the variations of the forces which are transmitted to the base via the crankshaft is achieved.

Cradle mobility can be achieved in different ways. For example, it is conceivable to allow the cradle to rest with straight and horizontal sliding guides perpendicular to the crankshaft and to load the cradle towards its center position with springs which thus act against the displacement. Instead of straight slide guides, it is also possible to use slide guides which are so curved and vertical that the cradle and the connecting rod rise more and more as the horizontal distance from the center position increases, so that the weight of the cradle and crankshaft counteracts the displacement.

However, it is more advantageous to hang the cradle on the base with articulated arms fitted on both sides of the crankshaft. Most preferably, these articulated arms are parallel or substantially parallel. The cradle may also support an engine that drives a crankshaft.

A Circular Saw made in accordance with the invention will be explained in more detail below with reference to the accompanying drawing.

Figure 1 is a side view of an embodiment of a circular saw according to the invention; in the figure the second side piece has been removed; Figure 2 shows the lower part of the reciprocating saw seen from the direction of the arrow II in Figure 1 to indicate direction.

The circular saw shown has a base 11 which stands on a concrete base 12. i request the guides 16, which co-operate with the sliding pieces 17 on the rigid saw ring 18, the so-called irtokcbi'ILTjto in which a plurality of parallel saw blades 19 are tensioned in vertical planes. the ring IS is connected to the connecting rod 15 and thus moves up and down in the stand when the crankshaft 14 rotates. The log or log to be sawn is fed in the usual way through the base and the saw ring by means of the upper and lower feed rollers 20.

According to the description so far, a circular saw is conventional. What is new is that the crankshaft bearings 14, 21 are not directly mounted on the base 11, a cradle 22 which is pivotally suspended in the stand for four parallel and equally long articulated arm 23, two on each side of the crankshaft. The cradle 22 is formed by two transverse cradle beams 24 rigidly connected to each other by longitudinal beams 25.

The cradle 22 may thus oscillate back and forth substantially horizontally and perpendicularly to the centerline of the axis of rotation of the crankshaft 14, within the limits set by the stops (not shown). The oscillation can take place freely, i.e. it is not coercively controlled, but is only counteracted by friction as well as within certain limits. inertia and gravity. When the cradle is suspended from the articulated arms as shown and thus rises slightly as it moves in either direction from the intermediate position, i.e. from the position where the articulated arms are vertical and the cradle and crankshaft are in their lowest position, gravity tends to return the cradle to this position.

As best seen in Figure 1, the cradle 22 also supports the drive motor 13, which thus participates in the rocking movements of the cradle.

As the saw ring 13 driven by the crankshaft drive 14, 15 moves up and down the saw 11 during sawing, the cradle 22 and thus the crankshaft 14 oscillate back and forth around its intermediate position on the articulated arms 23. The frequency of transverse oscillation movement is equal to phase shifted in this respect that the crankshaft and the cradle are in their leftmost position (seen as in Fig. 1) when the saw ring in its downward movement is in the middle of its end positions.

When the saw ring is in its upper or lower end position, the crankshaft and cradle are in the center position and when the saw ring is in the middle of its end positions when moving upwards, the crankshaft and cradle are in their right extreme position.

The amplitude of the transverse oscillation movement of the cradle depends on the geometrical relationships of the road, the masses of the cradle and crankshaft, etc. As an illustrative example, the distance from the center position of the crankshaft and cradle to each extreme position is about 5 cm. the weight is 5500 kg, the speed is 380 rpm, the lengths of the articulated arms 23 are 24 cm and their transverse distance is 150 cm. In this case, the total traction force on the pendulum arms varies, i.e. the force with which the cradle acts on the stand from 3300 kp to 3300 kp. The vertical component of this force is formed almost exclusively by gravity. The horizontal component ranges from 0 to about “50 kp. By way of comparison, it should be noted that the horizontal component would vary from 0 to about 14,000 kp if the crankshaft were fixedly mounted on a base, as is the case with circular saws used heretofore.

In the described embodiment, only gravity acts mainly against the transverse movements of the cradle. However, it is within the scope of the invention to fit springs or other elements which load the cradle towards its central position. Of course, it is also not necessary for the articulated arms 23 to be exactly parallel and vertical in the central position, but they can also be pre-arranged so that they tilt somewhat with respect to the vertical plane in the central position.