RU2215637C1 - Method of abrasive machining of holes with elastic screw tool - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: invention relates to abrasive machining of holes in machine component parts. Proposed method includes use of elastic tool consisting of body in form of bushing with radial slots and working cutting element in form of elastic metal tape with abrasive layer to which rotation relative to longitudinal axis and reciprocating motion are imparted. Working cutting element is made in form of elastic metal tape coiled in form of screw line, with number of turns not less than two, and pitch determined by dependence given in description of invention. EFFECT: increased accuracy and efficiency of machining, effectiveness of machining with abrasive grains, reduced calorific intensity of grinding process owing to screw-like arrangement of cutting surface, simplified control of machining and design tool. 3 cl, 3 dwg

Description

 The invention relates to mechanical engineering technology for abrasive machining of holes in machine parts.

 A known method of processing holes with an elastic tool, which contains a housing and a bearing working element part [1].

 The disadvantages of this method are the increase in temperature above the critical in the cutting zone at high grinding speeds, at which burns and microcracks are formed, in addition, low processing efficiency, since only 5. ..15% of abrasive grains are involved in cutting, the rest are non-cutting: some follow the trail of the previous grains and fall into previously cut grooves, and the chips are not removed, others - plastically deform the metal, others - are deeply recessed into the bundle and do not participate in cutting, etc. [Zubarev Yu.M., Priemyshev A.V. Technological fundamentals of high-performance grinding of steels and alloys - St. Petersburg: Izd. St. Petersburg University, 1994. S.18-20].

 A known method of processing holes with an elastic tool, which contains a housing and a supporting working element, the housing is made in the form of a sleeve with through radial slots located diametrically one another, and the supporting part is made in the form of an elastic metal tape, the ends of which are fixed in these slots, this working element is made in the form of an abrasive layer deposited on the outer part of the metal tape and (in another case) in the form of an abrasive tape with an adhesive applied on its non-working side tion [2].

 The disadvantages of this method are the increase in temperature above the critical in the cutting zone at high grinding speeds, at which burns and microcracks are formed, in addition, low processing efficiency, since only 5. ..15% of abrasive grains are involved in cutting, the rest are non-cutting: some follow the trail of previous grains and fall into previously cut grooves, and the chips are not removed, others - plastically deform the metal, others - are deeply recessed into the bundle and do not participate in cutting, etc.

 The objective of the invention is to increase the accuracy and productivity of processing, cutting efficiency with abrasive grains and reduce the heat stress of the grinding process due to the screw arrangement of the cutting surface and simplify the management of processing and tool design.

The problem is solved using the proposed method of processing holes with an elastic screw tool, in which an elastic tool containing a housing and a sleeve with radial slots and a working cutting element in the form of an elastic metal tape with an abrasive layer is reported rotational relative to the longitudinal axis and reciprocating movement, moreover, the working cutting element is made in the form of an elastic metal tape, rolled into turns of a helical line, the number of which is at least two turns, in increments
P = B _p - B _z ,
where In _p is the width of the working metal tape with an abrasive layer;
In _z = 0.5V _p - the width of the cavity between the turns.

 At the same time, the ends of the working tape are folded in a U-shape, have a latch and are fixed in the specified slots, and after each quarter of a revolution of the turn, the working metal tape has U-shaped corrugations fixed in the specified slots, the latter being located along a helical line.

 In addition, the introduction of an elastic screw tool into the hole to be machined is made by rotating it in the direction of the turns of the helical line of the working tape, and processing the hole of the workpiece is performed by rotating the tool against the direction of the turns of the helical line of the working tape.

 Figure 1 shows a diagram of the processing of the hole according to the proposed method and tool, General view; figure 2 is a section aa in figure 1; figure 3 is a view according to B in figure 1.

 The proposed method of processing holes with an elastic screw tool is carried out by an elastic tool, which contains a housing in the form of a sleeve 1 with radial slots 2 and a working cutting element in the form of an elastic metal tape 3 with an abrasive layer 4.

 The sleeve 1 is made of light material, such as duralumin. It is screwed onto a mandrel 5, made, for example, also of a duralumin tube.

 The tool consists of a bent elastic metal tape 3, made, for example, of steel 65G and other elastic materials by the method of cold rolling or can be heat-treated. It has a thickness of several tens of micrometers and thicker depending on the diameter of the hole being machined (range of holes).

Elastic corrugated metal tape 3 is folded into turns of a helix, the number of which is at least two turns, in increments
P = B _p + B _z ,
where In _p - the width of the working metal tape with an abrasive layer;
At _z = 0.5V _p is the width of the cavity between the turns.

 The ends 6 and 7 of the working tape 3 are bent and folded U-shaped, have latches 8 and are fixed in the indicated slots 2, and after each quarter of a turn of the turn, the working metal tape 3 has U-shaped corrugations 9, fixed in the specified slots 2, the latter located on a helix.

When processing holes according to the proposed method, the rotational V _p relative to the longitudinal axis and the reciprocating S _{pr of the} motion are reported to this tool. In addition, the input of an elastic screw tool into the hole to be machined is performed by idling in the direction V _{x of} turns of the helical line of the working tape, and processing of the hole of the workpiece is performed by rotating V _{p of the} tool against the direction of the turns of the helical line of the working tape.

 On the outer surface of the screw metal tape 3, which is in contact with the surface to be treated, by known methods, an abrasive layer 4 is applied on a flexible bond, for example, electroplating, etc. In another case, the abrasive working cutting surface 4 of the metal strip 3 can be made in the form of separate glued abrasive cloth sheets.

The working cutting surface thus obtained is a helical cylindrical abrasive surface with a cutting layer axially offset in the longitudinal direction, which contributes to a reduction in the processing temperature due to the depression B _z between the turns and free penetration of the cutting fluid into the cutting zone.

 In addition, the axially offset cutting layer of the helical tape contributes to the intensification of the grinding process, a larger number of cutting grains become workers who do not follow the previous ones, without falling into the previously cut grooves.

 Before work, the summer 3 rolled up in a helix is put on the sleeve 1 in such a way that the internal parts of the corrugations 9 fall into the through radial slots 2 located along the helical line on the cylindrical surface of the sleeve 1. The ends 6 and 7 of the tape are bent U-shaped and having bent lock 8, are also inserted into the corresponding through radial slots 2.

 An abrasive tape 4 is glued to the outer surface of the metal tape 3, and the tool is ready for use, although the tape 4 can be glued to the tape 3 earlier. When the sleeve 1 is rotated, the belt presses the abrasive belt 3 against the machined surface of the hole due to elastic forces and centrifugal forces. By changing the frequency of rotation of the tool, the radial force of the clamping pressure of the cutting layer is regulated and thus the magnitude of the radial feed is controlled.

When processing holes according to the proposed method, this tool is informed of a rotational V _p relative to the longitudinal axis, which is reversed, and a reciprocating S _pr movement. The reversal of the rotational motion V _{p is} performed for the following purpose. An elastic screw tool is inserted into the hole to be machined by rotating it idle in the direction V _{x of the} turns of the helical line of the working tape. So, on the tool shown in figure 1, the turns of the screw tape are in the left direction, which means that the tool is inserted when it is rotated counterclockwise, while the tape will enter the machined hole with the end 7 and twist, trying to decrease in diameter. This contributes to the free entry of the tape and the tool into the hole.

After the tool is completely inserted into the hole, the direction of its rotation is changed, and the workpiece hole is processed by rotating the tool _p V against the direction of the turns of the helical line of the working tape.

 So, on the tool shown in figure 1, the turns of the screw tape are in the left direction, which means that the holes are machined when the tool is rotated clockwise, while the tape will unwind, trying to increase in diameter. This contributes to an increase in the radial component of the cutting force and more intensive hole machining.

 The uniform action of the elastic forces of a metal tape rolled into turns of a screw surface increases the accuracy and productivity of processing, and also reduces the heat stress of the process due to the discontinuous cutting zone in the longitudinal direction.

 The runout of the sleeve 1 does not affect the runout of the metal tape 3, rolled into turns of a screw surface and freely placed by the ends 6 and 7 and the internal parts of the corrugations 9 in the grooves of the sleeve 1, since this tape simply slips in the grooves 2 of the sleeve 1.

As an example, a hole in a sleeve was machined on a mod grinding machine. 3K227B, equipped with a special elastic screw tool according to the proposed method. Material of the workpiece: pipe GOST 8734-75 / B40X GOST 8733-74, HB 280, the diameter of the hole to be machined ⌀125 mm, the cutting tool is a sandpaper on a fabric basis, roll, according to GOST 5009-82, waterproof, two-layer; abrasive material - 24A, grain size of the abrasive - 80. The sanding pad was glued in separate pieces with BF glue to the outer surface of a metal strip (steel 65G) 0.9 mm thick, obtained by cold rolling. Processing modes spindle rotation speed - V _in = 29.5 m / s (n _max = 4500 min ^-1 ), longitudinal feed S _pr = 3600 mm / min, machining allowance - 0.1 mm, tool pressure on the machined surface - 0.05 MPa, coolant - sulfofresol.

 The proposed method allows to increase the accuracy and productivity of processing by reducing the amount of runout of the tool with simplicity of design and reducing the metal consumption of the latter, to reduce the heat stress of the process due to discontinuous in the longitudinal direction and axially shifted cutting zone due to the helical arrangement of the cutting surface, to control the value of the radial feed due to centrifugal force and reverse the main rotational movement, as well as simplify machining control and tool design.

Sources of information taken into account
1. A.S. USSR 1028485, class B 24 B 33/02, 1983.

 2. A. p. USSR 1634469, class B 24 D 17/00, B 24 B 33/02. N.M. Harlov. The elastic tool for processing holes. Application 4387363/08, pending. 03/22/88, publ. 03/15/91. Bull. 10 is a prototype.

Claims (3)

1. The method of processing holes with an elastic screw tool, in which an elastic tool containing a housing in the form of a sleeve with radial slots and a working cutting element in the form of an elastic metal tape with an abrasive layer, rotational about the longitudinal axis and reciprocating motion, characterized in that the working cutting element is made in the form of an elastic metal tape rolled into turns of a helical line, the number of which is at least two, in increments
P = B _p + B _z ,
where In _p is the width of the working metal tape with an abrasive layer; B _z = 0.5 V _p is the width of the cavity between the turns.  2. The method according to p. 1, characterized in that the ends of the working tape are folded in a U-shape, have a latch and fastened in these slots, while after each quarter of a revolution of the turn, the working metal tape has U-shaped corrugations fixed in these slots, the latter are located on a helix.  3. The method according to p. 1 or 2, characterized in that the elastic screw is inserted into the hole to be machined by rotating it in the direction of the turns of the helical line of the work tape, and processing of the workpiece hole is made by turning the tool against the direction of the turns of the helical line of the work tape.

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