SU967403A1 - Device for chipless cutting-off of trees - Google Patents

Description

(54) DEVICE FOR CUT-FREE CUTTING

WOODWORKS

one

The invention relates to a device for cutting wood without chip and can be used for felling trees in the logging industry.

A device for brushless cutting of trees is known, which includes a base with a cutout mounted on it, an organ in the form of a curvilinearly curved blade with a pointed cutting edge {1.

However, such a device does not improve the quality of the cut surface and does not increase the yield of industrial wood.

The closest technical solution to the invention is a device for chipless cutting of trees, including a stand with clamping levers, two rotary cylindrical knives with unequal in area and inner and outer cutting edges, and hydraulic cylinders for driving knives 2.

A disadvantage of the known device is that its knife with a different ratio of the areas of the inner and outer edges of the blade will degrade the quality of the cut surface, increase the cutting force, which can lead to lifting the knife, breaking it and reducing the output of industrial wood.

The purpose of the invention is to reduce damage to the wood at the cutting point.

This is achieved by the fact that the inner cutting edge of the blade of the knife is made tangentially to the circumference forming the inner surface of the knife, and the outer cutting edge of the blade of the knife is formed by the part of the chord of the circumference forming the outer surface of the knife, forming the angle of the sharp edge of the blade of the knife , divides the thickness of a knife by a ratio of 1: 1 - 1: 4.

In addition, the ratio of the area of the inner surface of the cutting edge of the blade of the knife to the area of the outer surface of the cutting edge of the blade of the knife is 1.3-1.8.

15

FIG. 1 shows a device for cutting without cutting trees, front view; in fig. 2 - the same, side view; in fig. 3 - an embodiment of knives; in fig. 4 - the same.

20

The device for brushless cutting of trees consists of a rack 1 with clamping levers 2, two knife holders 3 with knives 4 fixed on them and hydraulic cylinders 5 for driving the knives 4.

Each blade 6 of knife 4 consists of converging inside line 7 and outer 8 facets. The intersection point of the inner 7 and outer 8 faces, which form the angle of the blade tip 6 of the knife, divides the thickness h of the knife in a ratio from 1; 1 to 1; 4. At the same time, the inside 7 of the cutting edge of the blade 6 of the knife 4 has a surface much larger than the outer 8 cutting edge of the blade. The ratio of these surfaces is between 1.3 and 1.8.

Such a cross-sectional shape of the blade point of the knife and the difference in the size of the surfaces of the inner and outer edges of the blade can significantly reduce the number and size of cracks during chipless cutting of trees.

The device works as follows.

With the knife-holders opened x 3 with the knives 4, the rack 1 is brought to the tree until it stops. Then, by turning on the hydraulic cylinders b, the knife holders 3 with the knives 4 are set in motion and the tree is cut. The clamping levers 2 begin to work simultaneously with the inclusion of the hydraulic cylinders 5 of the drive knives 4.

When cutting trees with a knife, significant deformations of the wood occur in the plane of its contact with the side surfaces of the blade of the knife and in the zone adjacent to these planes. The main resistance to the penetration of the knife is the resistance of the wood fibers to the deformation.

At the beginning, the top of the blade of the knife compresses and bends the wood across the fibers, forming a beam from them. Upon reaching the limiting values of compressive stresses across the fibers and tensile stresses along the fibers, the blade of the knife cuts the fibers and penetrates the wood, bending the cut fibers in the direction of the knife movement and squeezing them up with the edge of the blade. These stresses in the wood increase as long as the cut fibers of the beam-layer are in contact with the edges of the blade and take a certain constant value when they come into contact with the side surfaces of the knife. The magnitude of the stresses arising in the wood during chipless cutting depends on the height of the wood layer in contact with the side surface of the blade edge of the knife and the thickness of the layer beam. At the time of reaching the maximum values of these stresses, the wood breaks along the fibers and cracks form. The formation of cracks, as a rule, occurs in the zone of transition of the edge of the blade of the knife into the lateral surface of the knife.

Shifting the tip of the knife blade upwards relative to the axial line of the knife thickness and increasing the contact surface of the knife's edge with wood compared to the outer surface of the blade results in a decrease in the volume of wood exposed to the inside edge of the knife blade and an increase in the thickness of the bicate on the inner edge of the blade, which taken together leads to a decrease in stress in the wood and, thus, a significant decrease in the value of crack formation and an increase in the yield of industrial wood by 100-150 / 0.

The expected economic effect in comparison with the base object when installing the proposed knives on a logging machine is about 2000 rubles. in year.

Claims (2)

1. A device for chipless cutting of trees, including a stand with clamping levers, two rotary cylindrical knives with unequal inner and outer cutting edges and knives drive cylinders, characterized in that, in order to reduce damage to the wood at the cut point, the inner cutting face the blade of the knife is made tangentially to the circle forming the inner surface of the knife, and the outer cutting edge of the blade of the knife is formed by part of the chord of the circle forming the outer surface of the knife; intersection of tangent and chord parts forming wedge angle knife blade, divides the blade thickness in sootnoschenii 1: 1 -1: 4. 2. A device according to claim 1, characterized in that the ratio of the area of the inner surface of the cutting edge of the blade of the knife to the area of the outer surface of the cutting edge of the blade of the knife is 1,, 8. Sources of information taken into account in the examination 1. USSR Author's Certificate No. 391920, cl. B 27 B 23/00, 1971. 2. US Patent No. 3888287, cl. 144-34, 1975 (prototype). 1 r2 + + -H t + -N + -1+ +