RU2124429C1 - Rotary abrasive head for finishing holes - Google Patents

Abstract

FIELD: machine-tool industry; construction of abrasive finishing machines and rigging for finishing holes. SUBSTANCE: abrasive head has body which is secured on machine spindle, with honing sticks located inside it. Honing sticks have spherical working surfaces. Honing sticks are mounted for radial motion and for rotation relative to axis of hole being finished and relative to axis perpendicular to it. Head is also provided with mechanism for performing above-mentioned motions of honing sticks. This mechanism is arranged in body and is made in form of two kinematically linked shafts: one shaft is so positioned that its axis lies along axis of hole being finished and other shaft is located perpendicularly to it. Honing sticks are made in form of spherical segments fitted on second shaft symmetrically relative to first one and connected with this shaft by means of threaded joint providing for their radial motion. EFFECT: extended technological capabilities of tool; increased productivity at retained quality. 5 dwg

Description

 The invention relates to machine tool industry and can be used in the construction of abrasive finishing machines and equipment for finishing processing of holes from difficult to burn materials prone to burns.

 Known spindle grinding head containing a grinding wheel mounted in the holder, the axis of rotation of which is perpendicular to the Central axis of the holder / 1 /.

 However, this head can hardly be used for machining holes, due to the small, point contact of the abrasive tool with the work surface.

 As a prototype and the one closest to the proposed one, the head design for hole machining was taken, consisting of a housing, an expansion rod and blocks, in the holes of which cylindrical holders with honing bars with a spherical working surface with the possibility of reciprocating rotation are freely mounted, and the axes honing bars are offset relative to the axis of the head / 2 /.

 However, the known head requires increased specific pressures on the abrasive bars, which the bond does not withstand. In addition, the large energy costs associated with increased specific pressures limit the use of this head and are significant disadvantages.

 The objective of the invention is to expand the technological capabilities of the tool, improving the quality of processing and reducing energy consumption by providing alternating shear deformations in the surface layer.

 The problem is solved with the help of a developed rotary abrasive head designed for hole machining, containing a housing designed for fastening on the machine spindle, in which abrasive bars with a spherical working surface are located, mounted with the possibility of radial movement, and also with the possibility of rotation relative to the axis of the hole to be machined and the axis perpendicular to it, while the head is equipped with a mechanism located in the housing for the implementation of these movements . The mechanism for moving the bars is made in the form of two kinematically connected shafts, one of which is located on the condition that its axis is along the axis of the hole being machined, and the other is perpendicular to it, while the bars are made in the form of spherical segments, are mounted on the second shaft symmetrically to the first and connected with it through a screw connection, ensuring their radial movement.

 In FIG. 1 shows the proposed rotary abrasive head, General view; in FIG. 2 - the same, the second embodiment with an additional electric motor; in FIG. 3 is a section AA in FIG. 2; in FIG. 4 is a vector diagram of alternating shear deformations; in FIG. 5 is a section BB in FIG. 4.

 The rotary abrasive head for machining holes contains a housing 1 intended to be mounted on the machine spindle, in which a first shaft 3 is mounted on the supports 2, located along the axis of the machined hole and supporting mechanism 4 in the form of a conical pair of gears (Fig. 1). The mechanism 4 consists of a fixed bevel gear mounted on the housing 1 and movable, mounted on a second shaft 5, which is perpendicular to the axis of the machined hole.

The latter carries two abrasive bars 6 with a spherical working surface of radius R ₁ , which are made in the form of spherical segments. The first shaft 3 during its rotation with a frequency of ω ₁ transmits the motion to the bars 6 with a frequency of rotation of ω ₂ .
The bars 6 are mounted on the second shaft 5 symmetrically to the first and are connected with it by means of a screw connection, ensuring their radial movement.

 In addition to the purely mechanical drive discussed above, in FIG. 2 shows a screw head with an additional individual electric motor 7. The power supply of the electric drive is brought through the brushes 8 and slip rings 9.

The head works as follows. When the first shaft 3 rotates with an angular velocity of ω ₁ , and the bars 6 with an angular velocity of ω ₂ , the periphery of the bars describes a spherical layer 10 of height 2R _{2 of} radius R ₁ .

так как

В точке 12 линейная скорость
V₁₂ = ω₁•R₁
Благодаря такому распределению скоростей любая точка шарового пояса 10 имеет скорость, отличную от нуля, что позволяет производительно вести обработку.Moreover, at point 11 on surface 10, the linear velocity

as

At point 12, linear velocity
V ₁₂ = ω ₁ • R ₁
Due to this distribution of speeds, any point of the ball belt 10 has a speed other than zero, which allows efficient processing.

 In addition, the efficiency of the grinding process is increased due to the creation of alternating shear deformations in the sheared layer of the workpiece.

 Consider the scheme of abrasive machining of the holes of the proposed rotary head (Fig. 4, 5).

A spherical bar, rotating with a frequency of ω _2, cuts off the next layer (position 1) of the allowance and forms a texture with the vector ε $\genfrac{}{}{0ex}{}{\text{1}}{\text{n}}$ downward shear strain if the cutting grains are to the left of point 12, and with the vector ε $\genfrac{}{}{0ex}{}{\text{1}}{\text{in}}$ - up if the cutting grains are on the right. When the head rotates with a frequency of ω ₁ and axial motion S _{pr, the} ball block, occupying position 2, cuts off the allowance layer and forms the texture ε $\genfrac{}{}{0ex}{}{\text{2}}{\text{n}}$ surface layer directed against the vector ε $\genfrac{}{}{0ex}{}{\text{1}}{\text{in}}$ ball bar speed relative to the first position. Carrying out cutting in this way, the spherical bars automatically create alternating shear deformations in the surface layer of the workpiece and constantly carry out cutting against the direction of the vectors ε _n and ε _{in the} texture of the cut layer. As a result, the cutting force is reduced and the processing productivity is increased.

 The rotor head allows you to increase the cutting depth by two or more times, while microcracks, burns and chips do not appear on the treated surface.

 The use of the head significantly reduces energy consumption per unit volume of metal, increases the processing productivity several times while maintaining the product quality in terms of roughness and residual stresses. A characteristic feature of the head is an intermittent path path due to the alternation of grains in contact with the workpiece. Thanks to the local contact zone and the change of the cutting grains of the spherical bars, the heat balance of the tool improves, its resistance increases, and salinity decreases. The free supply of cutting fluid to the treatment zone also increases the productivity of the treatment.

 The proposed rotary abrasive head for hole processing expands the technological capabilities of the tool, ensures processing performance while maintaining product quality, reduces energy consumption per unit volume of metal due to the provision of alternating shear deformations in the surface layer and cutting against the direction of the texture of the cut layer.

 The rotary head is a promising abrasive tool for machining holes, because allows you to several times increase the cutting speed and processing performance compared to a traditional tool.

Sources of information:
1. A.S. USSR N 1286398, class B 24 B 41/04, 1987, BI N 4.

 2. A.S. USSR N 573328, cl. B 24 B 33/08, 1977, prototype.

Claims (1)

 A rotary abrasive head for machining holes, comprising a housing intended for placement on the machine spindle, in which abrasive bars with a spherical working surface are located, mounted with the possibility of radial movement, and also with the possibility of rotation relative to the axis of the machined hole and an axis perpendicular to it, while the head equipped with a mechanism located in the housing for the implementation of these movements of the bars, characterized in that the mechanism for moving the bars is made in the form of two kinematically connected shafts, one of which is located on the condition that its axis is along the axis of the hole to be machined, and the other is perpendicular to it, while the bars are made in the form of spherical segments, are mounted on the second shaft symmetrically to the first and connected to it by means of a screw connection ensuring their radial moving.

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