RU2043877C1 - Composite cutting tool - Google Patents

Abstract

FIELD: mechanical engineering, production and operation of composite cutting tools equipped with wide-spread replaceable mechanically fixed plates with cylindrical opening free of face. SUBSTANCE: cutting tool has body, cutter plate and fastening member formed as screw with eccentric. Geometric parameters of eccentric and eccentricity value are evaluated in accordance with ratio recited in Specification. EFFECT: increased efficiency and easy maintenance of cutting tool. 2 dwg

Description

 The invention relates to mechanical engineering and can be used in areas related to the production and operation of prefabricated cutting tools equipped with the most common interchangeable mechanically fixed plates with a cylindrical hole without a bevel.

 Known designs of prefabricated cutters, the fastening of the cutting inserts in which is carried out using the L-shaped lever.

 The disadvantage of this design is poor manufacturability, difficulty in manufacturing, which is associated with high requirements for dimensional accuracy and relative positioning of the surfaces of the elements.

 A cutter also has a similar disadvantage, in which the insert is mounted by means of oblique thrust.

 Known cutter, which is the prototype, the fixing of the cutting insert in which is carried out using a screw with an eccentric head.

 However, a force closure can be carried out only on one side base surface provided that the angle of self-braking and non-rotation of the eccentric is ensured and when vibrations occur during the cutting process, these conditions are violated, the eccentric is rotated and the cutting insert is released. The use of additional locking elements leads to a complication of the structure due to the introduction of new elements, the cost of the tool, the deterioration of its manufacturability and does not guarantee against unfastening during vibration.

 The aim of the invention is to increase the vibration resistance of the tool.

≥ e ≥

где φ arctg

угол трения;
Ψ arctg

угол подъема резьбы;
f коэффициент трения с учетом вибраций (f ≈ 0,02);
Р шаг резьбы;
d₂ средний диаметр резьбы;
f₁ коэффициент трения пары материал эксцентрика-материал режущей пластины;
d_отв диаметр отверстия в пластине;
S высота головки эксцентрика;
d диаметр упругой перемычки;
l общая длина эксцентрика;
Е модуль упругости материала винта, а диаметр d_е головки винта выбран по формуле d_e= d_отв- 2

l
Сущность изобретения заключается в создании условий, при которых эксцентрик при прохождении кратчайшего расстояния от оси винта до боковой базовой поверхности, т.е. при повороте (за счет упругих деформаций) попадает в "мертвую" зону, положение которой определяется биссектрисой угла, образованного двумя боковыми базовыми поверхностями (угол гнезда). В данном положении эксцентричная головка при возникновении вибраций не сможет повернуться, так как при повороте в этом и другом направлении возрастает момент сопротивления. При этом за счет сил упругости существенного изменения силы закрепления режущей пластины не произойдет.This is achieved by the fact that the fastening element is made in the form of a screw with an eccentric head, and an elastic bridge is made between the head and screw, while the eccentricity of the e head is selected by the formula

≥ e ≥

where φ arctg

angle of friction;
Ψ arctg

angle of thread;
f coefficient of friction taking into account vibrations (f ≈ 0.02);
P thread pitch;
d ₂ average thread diameter;
f _{1 the} coefficient of friction of the pair of material of the eccentric material of the cutting insert;
hole diameter d _{of holes} in the plate;
S is the height of the cam head;
d diameter of the elastic bridge;
l total length of the eccentric;
E is the modulus of elasticity of the screw material, and the diameter d _{e of the} screw head is selected by the formula d _e = d _resp - 2

l
The essence of the invention is to create conditions under which the eccentric during the shortest distance from the axis of the screw to the lateral base surface, i.e. when turning (due to elastic deformations), it falls into the "dead" zone, the position of which is determined by the bisector of the angle formed by two lateral base surfaces (nest angle). In this position, the eccentric head will not be able to turn when vibrations occur, since when turning in this and the other direction, the moment of resistance increases. In this case, due to the elastic forces, a significant change in the fixing force of the cutting insert will not occur.

 The construction of the tool and the diagram explaining the operation of the mechanism are shown in FIG. 1 and 2.

 The design consists of a housing 1, in the socket of which a cutting insert 2 is mounted, connected to the housing by a fastening screw 3 with an eccentric head 4, the head and the screw being connected by an elastic jumper.

 The device operates as follows. A cutting insert 2 is installed in the housing socket 1, the hole of which includes an eccentric head 4 connected to the screw 3 by an elastic jumper. When the screw is rotated, its axial movement is carried out with the simultaneous rotation of the eccentric head, which initially carries out a force circuit to the side base surface. At the shortest distance, the maximum fixing force is ensured, and when passing through this position, the head falls into the "dead" zone, which protects it from spontaneous rotation during vibrations during cutting.

 The invention allowed to exclude the occurrence of a cutting insert observed in a similar design during vibrations during cutting.

 The invention can be used in almost any type of precast tool.

Claims (1)

ASSEMBLY CUTTING TOOL, in the housing socket of which there is a cutting insert with a hole fixed by a screw with an eccentric head, characterized in that an elastic bridge is made between the head and screw, while the eccentricity of the head is selected by the formula

Where

angle of friction;

angle of thread;
f coefficient of friction taking into account vibrations (f≈0.02);
p thread pitch;
d ₂ average thread diameter;
f ₁ coefficient of friction of a pair of material of the screw material of the cutting insert;
d _{about t in the} diameter of the holes in the insert;
s screw head height;
d the diameter of the elastic bridge between the head and screw;
l total head length;
[σ _and ] permissible bending stresses of the screw material;
E is the modulus of elasticity of the screw material,
and the diameter d _{e of the} screw head is selected by the formula

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