RU2517671C2 - Modular grinder for hole processing - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and can be used for bore grinding with cooling of rotary or stationary blanks. Modular grinder comprises at least two identical modules fitted on tool holder and jointed together by their butts and centred relative to the tool rotational axis. Every module comprises the case with radial guides for identical segments radially displacing therein and furnished with hones fitted at their ends. Modules at tool holder can be fed into bore to be roughed and finished and allow replacement of segments with worn-out hones with tool dismantling.

EFFECT: higher efficiency of grinding, simplified replacement.

5 cl, 3 dwg

Description

The invention relates to mechanical engineering and can be used at enterprises of the metalworking industry for roughing, semi-finishing and finishing abrasive or diamond processing of workpieces from various materials.

Known cutting tools combined processing cycle (patent RU No. 2153976, patent RU 2153973, patent RU No. 2153967, patent RU No. 2275295, patent RU No. 2252132, patent RU No. 2182075), characterized by additional mechanisms or devices for the forced feeding of cutting elements (segments) for final processing cycle. A disadvantage of the known tools is the low manufacturability of the design, due to the large number of precise parts and their relatively complex shape. The second (final) grinding step is carried out only after external action on the tool by the stationary control. The disadvantage of tools made in accordance with the above patents is also the difficulty of replacing worn cutting segments.

There is also a known method and tool for internal grinding (Patent RU No. 2000101135). A rotating tool with radially movable segments is placed in a container formed by the workpiece’s machined surface and side covers and filled with cutting fluid (coolant). A rotating tool spins the coolant and creates a high coolant pressure on the workpiece surface and the cutting zone, which contributes to its deeper penetration into the local contact areas of cutting abrasive grains and the workpiece, which contributes to an increase in the rate of removal of heat generated in the cutting zone.

Also known is a cutting tool with radially movable grinding segments (prototype) for processing internal cylindrical surfaces (Patent RU No. 18057). The tool consists of a body in which radial grooves and grinding bars are placed in a metal holder. When the tool rotates under the action of centrifugal force, the segments move along the radial grooves and come into contact with the workpiece, removing the allowance. The processing scheme is carried out according to the method of internal grinding (Patent RU No.2000101135). The disadvantages of the known tool are: low manufacturability of the design of the tool, due to the relatively high complexity of the geometric shape of the parts guiding the radial movement of the segments during processing, as well as high requirements for dimensional accuracy (small tolerances) of grinding bars and holders. A disadvantage of the known tool is also the difficulty of replacing segments with worn grinding bars, which can be realized only after complete disassembly of the tool.

The technical effect achieved by the invention is to increase the manufacturability of the tool design, simplifying the replacement of segments with worn grinding bars and increasing the productivity of the internal grinding process.

Improving the manufacturability of the tool design is achieved by the fact that the tool is made in the form of identical modules in design, which are rigidly fastened to each other and centered relative to the axis of rotation of the tool by abutting surfaces located on the side of the ends of each module. Each of the modules consists of a housing in which radial holes are made, which play the role of enclosing guides. A segment is inserted into each radial hole of the housing, the peripheral end of which is made in the form of a platform with a grinding bar fixed to it. The cylindrical surface of the segment plays the role of a covered guide during radial movement of the segment in the housing. The number of segments in each module varies from 2 or more depending on the diameter of the workpiece’s bore hole.

Simplification of the replacement of a segment with a worn bar is achieved by providing free access to any segment, regardless of its location in the tool. To replace a segment with a worn bar, it is enough to unscrew the pin, whose axis is perpendicular to the cylindrical guide.

Improving the performance of the internal grinding process is achieved by performing preliminary and final grinding cycles without replacing the processing equipment.

Variation of the pressing force of the grinding bars to the workpiece surface to be treated within a wide range is achieved by changing the tool speed and adjusting screws installed in the central hole of the segment housing. Each module is provided with one or more sets of adjusting screws of various weights. Each set consists of a set of identical (by weight) adjusting screws having a simple cylindrical shape with an external thread and a groove for a screwdriver on one of the ends.

To exclude damage to the workpiece’s work surface, segments that were idle at the considered time, a device was installed in the module housing that returned each segment to its original position, while the number of devices is equal to the number of segments. The device consists of magnetic sections located on the outer cylindrical surface of the module housing. If the value of the inertial centrifugal force acting on the segment is less than the magnetic forces generated by the section from magnetic material, then the segment moves with the cutting bar in the radial direction to the axis of the tool.

The invention is illustrated by drawings: figure 1 - modular grinding tool with radially movable segments; figure 2 - the module of the tool: a) with extended to the maximum radius of the segments; b) with segments extended to the minimum radius; figure 3. - segment.

Two or more modules 2 identical in design are mounted on the tool holder 1 (Fig. 1), which are centered relative to the axis of rotation of the tool using centering surfaces located on the ends of each module 2 and the mandrel 1. Depending on the metal-cutting equipment used and the coolant supply method inside the tool body, the mounting surfaces of the mandrel 1 are made in various designs. The fastening of the modules 2 to the mandrel 1 is carried out by a set of screws 3, the length of the screws of each set depends on the number of installed modules 2 in the tool.

The grinding tool module (Fig. 2a) is made in the form of a one-piece housing 4 with radial cylindrical holes (covering guides). A segment 5 is inserted into each radial hole. The number of segments 5 depends on the diameter of the workpiece hole being machined and other design parameters of the tool. To limit the radial movements of segment 5, as well as to prevent its rotation around its axis, a pin 6 is screwed (Fig.2b), the ends of which are included in the radial grooves 7 made at the ends of the housing 4. The length of the groove 7 is equal to the maximum value of the radial movement of segment 5.

To automatically return segment 5 to its original position (to the position with segments shifted by the minimum radius (Fig.2b)) after the termination or before the start of the processing process, magnetic sections 8 are rigidly mounted on the outer surface of the housing 4 (Fig.2a), the number of which is equal number of segments.

A through central hole in the housing 4 (figa) is designed to supply coolant inside the tool body. Coolant is supplied to the tool body either through a spindle mandrel, or by other devices and mechanisms of the machine. When the tool rotates, the coolant passes through the grooves 9 (Fig.2b), heading at high speed to the workpiece surface being machined.

The segment (Fig. 3) consists of a housing 10, on the peripheral end of which there is a platform for installing and securing the grinding bars 11, the pin 12 and the adjusting screw 13. The grinding bars 11 are rigidly fixed to the platform with threaded elements or with glue. In the latter case, at the end of the housing 10 around the perimeter are flanges from all 4 sides, which ensures the fixation of the bar 11 from displacements relative to the platform. The small size of the beads (up to 5 mm) ensures maximum use of the grinding material, which leads to an increase in the utilization of the material and the resource of the bar.

The tool works as follows.

After assembly, the modular grinding tool is mounted on the spindle of the internal grinding machine and the working surfaces of the grinding blocks are corrected with a ruling diamond tool. Editing is carried out by rotating the tool and with the segments extended as far as possible. Before starting work, the tool is introduced into the workpiece’s machined hole so that the necessary modules are completely inside the machined hole. After turning on the coolant supply, the internal cavity of the instrument is filled with coolant. Under the action of centrifugal force arising from the rotation of the tool, the coolant is ejected from the tool at high speed through radial grooves made in the tool body, forming a high pressure coolant ring on the surface to be treated. When the value of the centrifugal force is greater than the magnetic forces created by the magnetic sections, the working surfaces of the grinding bars are pressed against the workpiece surface, removing the allowance.

A grinding tool consisting of two or more modules has a different characteristic of the grinding material of the bars of each module. The modules are mounted relative to each other at an angle, which ensures the location of the segments with grinding blocks in a “checkerboard pattern” and free access to the pins. This installation of modules also ensures uniform distribution of the thermal field over the entire surface of the workpiece and enables the assembly and disassembly of any segment with a grinding bar without disassembling and dismantling the entire tool from the machine (when installing two or more modules for each processing cycle).

The execution of all modules in the same design ensures their full interchangeability, reduces the range of parts used in the grinding tool, and the implementation of critical guides in the form of typical cylindrical surfaces simplifies their manufacture and assembly. The above increases the manufacturability of the design of the grinding tool as a whole.

Consider a grinding tool consisting of two modules. The first module, assembled from the side of the spindle mandrel, contains grinding wheels for preliminary grinding (grinding material with a larger grit number and a more open structure and higher hardness), and the last module to be connected for final grinding (grinding material with a lower grit number and a denser structure) and less hardness). This ensures that the combined hole processing on one machine, one tool, without reinstalling the workpiece.

To replace a segment with a worn-out grinding bar, it is necessary to unscrew the pin 6 (fig.2b), restricting the radial movement of the segment, remove the segment 5 (Fig.2a) with the worn-out grinding bar from the radial hole of the casing 4, to replace it with a new grinding bar, then screw pin 6. Replacement of any segment is carried out without removing the tool from the machine spindle and without disassembling the tool, regardless of the location of the segment in the tool, which reduces the auxiliary time to complete of the grinding operation.

Claims (5)

1. A modular grinding tool for processing holes, comprising at least two mounted on a spindle mandrel module identical in design, rigidly fastened to each other by ends and centered around the axis of rotation of the tool, each module comprising a housing with radial guides made in it, in which with the ability to move in the radial direction, radially movable identical segments are installed with grinding bars fixed to their end, and the modules on the spindle The flax mandrel is installed with the possibility of sequential input into the machined hole to ensure preliminary and final grinding and with the possibility of replacing segments with worn grinding bars without disassembling the tool. 2. The grinding tool according to claim 1, characterized in that at the ends of the modules and the spindle mandrel, centering surfaces are made. 3. The grinding tool according to claim 1, characterized in that the guides of the cases of the modules and segments have a cylindrical shape. 4. The grinding tool according to claim 1, characterized in that it is equipped with devices integrated in the housing of the grinding module for returning each segment to its original position relative to the axis of the tool. 5. The grinding tool according to claim 1, characterized in that the modules on the spindle mandrel are installed at an angle relative to each other with the location of their segments in a checkerboard pattern.

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