RU2215641C2 - Device for measuring low-contact forces at electric diamond grinding - Google Patents

Abstract

FIELD: metal working; force measuring facilities. SUBSTANCE: proposed device contains housing secured on table of tool-grinding machine which accommodates holder 11 and strain measurement insert 3. Antifriction bearings mounted on holder 11. Stop plate 5 is secured on opposite end of holder. Holder is held vertically by bearings 10 and 12 press-fitted on two axles held by nuts of housing. Holder is fixed in horizontal direction by four bolts with ball press-fitted into end face of each bolt. Under action of cutting force, holder 11 deforms strain measurement insert 3, and by change of resistance of insert, cutting is evaluated. EFFECT: enlarged operating capabilities. 3 cl, 2 dwg

Description

 The invention relates to devices for measuring cutting forces and can be used in the study of processes of diamond grinding.

 A known construction of a strain gauge dynamometer [1]. The forces Px, Ru, Pz applied to the cutter fixed in the special holder are transferred to the elastic elements made in the form of half rings faceted from the outside. Wire sensors are glued on the faces and inner cylindrical surfaces of each element. For example, the force Py is perceived by the sensors, while the external sensors are stretched, and the internal sensors are compressed. The force Pz creates a bending moment, as a result of which the sensors of the upper belt are stretched, and the sensors of the lower belt are compressed. The force Px is sensed by sensors glued on the outer sides.

 The disadvantage of this device is the cumbersome design and the inability to determine small forces when grinding metals.

 Also known is the design of a universal dynamometer UDM design VNII [2]. The cavity of the housing in which the holder is placed is made in the form of a square plate with a round flange on the upper part. The round flange of the holder is designed for fixing on the diameter of interchangeable devices: tool holder or table. The holder is installed in the housing on 16 elastic supports. Each support consists of a thin-walled sleeve and two legs. The legs form two elastic joints. The cross-sectional areas of the sleeve and legs of the support are equal and selected so that the material of the support works in the field of elastic deformations. Supports are installed in guide bushings. Each of the supports of the dynamometer has a preload, which slightly exceeds half the load maximum permissible for the support. Thanks to the tightness of the bearings, all gaps and contact deformations in the joints of the dynamometer parts are eliminated. The tightness of the supports is regulated by turning the nuts. After adjusting the preload value, the nuts are fixed with crackers and closed with lids. Wire resistance sensors are glued to the bushings of the supports. On the support, the axes of which are located vertically, one sensor is glued, which are connected to the measuring circuits of forces Ru and Px, the second sensors to the measuring circuit MKR. The wires from each sensor are routed through the holes in the dynamometer body to the panel and connected to the terminals. On the panel, sensors are connected to measuring circuits. The cavity cavity of the dynamometer in which the panel is located is covered with a lid. The wires from the measuring circuits are routed to a detachable chassis.

 The disadvantage of this design is the inability to determine small forces during grinding.

 EFFECT: possibility of determining small cutting forces during electro-diamond grinding with superhard materials.

 The technical result is achieved as follows. In order to measure the component of the cutting force, the holder must be deprived of five degrees of freedom, this condition is satisfied with the help of rolling bearings. Due to the fact that rolling friction is present in the structure, it can be assumed that the friction forces are negligible and can be neglected. In the process of sharpening, cutting forces are freely transmitted to strain gauges and recorded by a recorder. The design of strain gauges allows you to rigidly fix the position of the holder and thereby deprive him of the sixth degree of freedom. This leads to the fact that the force Py is transmitted directly to the load cell. Since the rod – strain gauge system is rigid, it can be assumed that the elastic forces inherent in mechanical dynamometers are absent or negligible.

 In FIG. 1 shows the design of a device for measuring small cutting forces, a section along AA in FIG. 2; figure 2 is a side view.

 The device consists of a holder 11, to the body of which on the axes 18 and 21 are installed rolling bearings 27, 28 and 33, 34. A quick-change head 14 is fastened to the holder with bolts 31 and 32 for fastening the sanding sample 15. At the opposite end, a locking plate 5 is fastened with a bolt 7 and fixed by nut 6. The holder is mounted in the housing 9 and is fixed in the vertical direction by bearings 10 and 12, which are pressed into two axles 26. By means of four nuts 25, the axles are attached to the housing 9. The housing of the device is mounted on the table 17 of the grinding machine NCA bolt 19 and the nut 20. To protect the bearings from dust and the electrolyte are provided plate 8 and 13.

 To give rigidity in the vertical direction to the bottom of the quick-change head, a bearing 16 is pressed, pressed onto the axis 30 and fixed at the required height by two bolts 29. In the horizontal direction, the holder is fixed by four special bolts 24, the end of which is ball 22, which is necessary to reduce the coefficient of friction o holder housing and providing the required rigidity. A nut 23 is provided for fixing the bolts.

 To measure the radial force of Ru, a strain gauge insert 3 with wire resistance sensors (R = 200 Ohms) is installed, located between the bolt 2 and the body protrusion. The clamping force is regulated by nut 1.

 The principle of operation of the dynamometer is based on the conversion of mechanical displacements during the deformation of sensitive elements into a change in ohmic resistance.

 The device works as follows. Under the action of the cutting force, the strain gauge insert 3 is deformed; when loading with the radial force Ru of the grinded sample 15, the holder 11, deprived of five degrees of freedom by means of rolling bearings 10, 12, 27, 28, 33, 34 and the sixth degree of freedom - by pressing the strain gauge insert 3, presses on it through the ball 4. At the slightest change in pressure the resistance on the strain gauges connected to the bridge circuit changes, as a result of which the current in the circuit changes. The change in current strength under the influence of changing voltages is recorded by a milliammeter or oscilloscope after a preliminary, significant amplification with the help of an amplifier.

 Thus, this design of the device allows you to measure the small radial forces that occur during grinding, which are used to judge the cutting ability of the grinding wheels.

SOURCES OF INFORMATION
1. Wulf A.M. Metal cutting. M.- L .: Mashgiz, 1963, 428 pp., Ill.

 2. Guide to the universal dynamometer UDM design VNII. M., 1983.

Claims (3)

 1. A device for measuring small forces during electro-diamond grinding, comprising a housing mounted on a table of a grinding machine in which a holder is mounted, a strain gauge insert, characterized in that the bearings are mounted on the holder and a quick-change head for attaching the grinding sample, and is mounted on the opposite end of the holder locking plate, in the vertical direction, the holder is fixed by bearings, which are pressed in on two axes attached by nuts to the housing, in horizontal The direction of the holder is fixed with four bolts, which are pressed into the end of the ball, while under the action of the cutting insert holder deforms the strain gauge, which resistance change by judging the magnitude of cutting forces.  2. The device according to claim 1, characterized in that a bearing pressed onto the axis and fixed at a certain height is pressed against the bottom of the quick-change head.  3. The device according to claim 1, characterized in that the strain gauge insert has wire resistance sensors.

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