GB2231290A

GB2231290A - Milling cutter grinding machine

Info

Publication number: GB2231290A
Application number: GB8909388A
Authority: GB
Inventors: Gencho Antonov Sirakov; Pavko Trifonov Pavkov; Racho Ivanov Stoev; Vessalin Petrov Shopov; Mariana Hristova Kovacheva
Original assignee: Z SIM
Current assignee: Z SIM
Priority date: 1989-04-21
Filing date: 1989-04-25
Publication date: 1990-11-14
Also published as: NL8901027A; DE3913246A1; GB8909388D0

Description

:2:2 3 I_,p, tD 0 1_ GRINDING MACHINE This invention relates to grinding

machines and more particularly to an arrangement for two-sided face grinding of cutting-off milling cutters which find application in tool manufacture.

A machine for two-sided face grinding of cuttingoff milling cutters which is described in USSR Inventors Certificate No.921,796 comprises a frame on which there is mounted a fixed table with a chuck for rigid axial clamping of a machined cutting-off milling cutting and for transmission of rotational motion thereto. On each side of the milling cutter, there are disposed symmetrically two displaceable grinding heads with an associated system for automatic regulation of the feed of each head and a mechanism for active checking of the symmetry of the profile being imparted to the machined milling cutter.

A draw-back of this known machine for grinding cutting-off milling cutters is its complicated design, in comprising two displaceable grinding heads each having a feed system and a system for control of the feed which is adjustable according to requirements. Moreover it is not possible to grind cutting-off milling cutters without a hub mounting for them because of the practice of clamping and of transmission of rotational motion to the machined milling cutter. Another problem lies in the low productivity when machining thin milling cutters because, during the approach of both grinding heads, in order to avoid deformation of the axially fixed cutting-off milling cutter, the systems for automatic regulation determine that the grinding head which first reaches the cuttingoff milling cutter and also the head which is last involved in the grinding undergo relatively small amount of travel.

is According to the present invention, there is provided an arrangement for two-sided face grinding of cutting-off milling cutters, which comprises two grinding heads for acting on opposite faces of a said cutter, one grinding head being fixed with respect to linear displacement and the other being capable of linear displacement, both being capable of angular displacement, the grinding heads each having associated therewith an electric motor connected to a system for active checking of the machined size of the cutting-off milling cutter, which system is associated with a mechanism for compensating for the wear of both grinding heads and with a mechanism for incorporating for the allowance for grinding.

More particularly, this invention provides an arrangement for two-sided face grinding of cutting-off milling cutters which comprises a workpiece support and a grinding head provided on either side thereof each having an associated intotor for rotating a grinding head spindle and being electrically connected to a system for automatic regulation of the feed and a system for active checking of the machined size of the cutting-off milling cutter, one grinding head being incapable of linear displacement and the other being linearly displaceable in a housing in which there is disposed a slider device carrying a support on which angular adjustment of rotation of the other grinding head is effected, to which slider device there is rigidly attached a hydraulic cylinder for achieving a rapid positioning stroke and having a piston coupled to a drive means therefor disposed in a housing in which there is rigidly secured a mechanism for compensating for the wear of both grinding discs, and wherein the support means for radial locating of the machined milling cutter is disposed between the grinding heads, being rigidly mounted on a slider device seated in a housing of a positioning carriage, in which housing there is disposed a mechanism for compensating the allowance for grinding which is operatively associated with mechanism for compensating for wear of the grinding disc, there additionally being mounted rigidly on that slider device to which the radial locating means is secured a support carrying a motor for driving a guide roller which is to be in contact with the machined milling cutter and which is opposed to a pressure roller which is juxtaposed with respect to a lever which can act thereon and which is connected by means of a sensor for linear measurement to the system for active checking of machined size of cutting- off milling cutter.

The mechanism for compensating for allowance of grinding comprises in preferred practice a single acting hydraulic cylinder with piston having an adjustable stop associated therewith, the single acting hydraulic cylinder being rigidly secured to a second hydraulic cylinder comprised by the mechanism for compensation of wear of the grinding disc of the fixed grinding head, the second hydraulic cylinder having a piston rod which is rigidly connected to a clamp to which there is-rigidly secured a third hydraulic cylinder with piston rod pivotally connected to a wedge-shaped device which is held to secure a frictional connection between the slider device on which the radial locating means for the machined milling cutter is located and the clamp.

An arrangement embodying the invention has the advantage as far as twosided face grinding of cuttingoff milling cutters is concerned of simplified design since there is only utilised one system for automatic regulation and one DC drive, being the drive for the feed of the displaceable grinding head. It is possible with the arrangement of the invention to effect on the arrangement machining of cutting-off milling cutters with or without a hub at guaranteed constant size accuracy, regardless of allowances which have to be made for grinding. The equipment possesses a particularly large production capacity when machining cutting-off milling cutters of relatively small thickness.

For a better understanding of the invention and to show how the same can be carried into effect reference will now be made byway of example only to the accompanying drawings wherein:- FIGURE 1 is a generalised plan view of an arrangement embodying the invention and FIGURE 2 is a kinematic diagram of the arrangment.

An arrangement for two-sided face grinding of cutting-off milling cutters which embodies the invention comprises a frame 1 at a forward pa:,t of which there is mounted a fixed housi--,.:; a carriage arrangement 3 for the positioning of a machined milling cutter 4 To one side of the position at which the machined milling cutter 4 is located is mounted rigidly a housing 32 for a fixed, i.e. incapable of linear motion, grinding head 33 which itself carries a table 34 for angular adjustment of its grinding spindle 35 and grinding disc 36, the spindle 35 being driven by an electric motor 37. The angular adjustment takes place in a horizontal plane and the spindle 35, disc 36 and motor 37 are rigidly fastened to the table 34. Also mounted on the table 34 is a dressing or sharpening device 38 (see Figure 1).

On the opposite side of the position at which the machined milling cutter 4 is located to the grinding head 33 with its table 34 there is mounted a displaceable grinding head 40 in the housing 39 of which there is situated a slider device 41 carrying a 1 table 42 for angular adjustment of a grinding disc 44 mounted on a spindle 43 rigidly attached to the table 42, driven by an electric motor 45 and having its own dressing device 46 (Figure 1). Rigidly fastened to the slider device 41 is a hydraulic cylinder 47 with a rapid adjustment stroke and having a piston 48 to which there is secured a nut 49 running on a drive screw 50. The drive screw 50 is positioned radially-axially to the frame 1 of the arrangement and is connected to a DC high-torque electric motor 52 by means of a reduction gear 51 whose output shaft 53 is connected to the drive screw 50 by means of a clutch device 54. The reduction gear 51 is located in a housing to which is rigidly secured a mechanism 55 for effecting compensation of is the wear of grinding discs 36 and 44 and consisting of a stop 56 and a limit switch 57 fixedly mounted on the housing of mechanism 55 within which there are also located on the output shaft 53 a friction disc with cam 58 and spring 59.

The machined milling-cutter 4 is shown in position between the fixed grinding head 33 and the displaceable grinding head 40. It is secured to a mandrel 19 for radial locating of its machined milling cutter 4 with respect to the grinding discs 36 and 44, the mandrel 19 being rigidly mounted on a slider device 17 which is seated in housing 2 of the carriage 3 for positioning of the machined milling cutter. Within the housing 2, there is disposed a mechanism 5 for effecting compensation allowance for grinding and which is connected to a mechanism 10 for compensating for the wear on the grinding disc 36 of the fixed grinding head 33. The mechanism 5 consists of a single acting hydraulic cylinder 6 with piston 7 and adjustable stop 8 which is rigidly secured to the housing 2 in which it is disposed. Rigidly secured to the single action hydraulic cylinder 6 is a second hydraulic cylinder 9 -6 of the mechanism for compensating for wear on the grinding disc 36 of the fixed grinding head 33. The second hydraulic cylinder 9 contains a piston 11 whose piston head 13 is rigidly secured to a clamp 12 to which there is in turn secured rigidly a third hydraulic cylinder 14 with piston rod 15 which is pivotally connected to a wedge shaped member 16 which effects a frictional connection between the slider device 17 in the housing 2 and the clamp 12 by means of fixators 18. Mounted to the slider device 17 is a table 20 on which is mounted a motor 22 connected to a reduction gear 21 on the output shaft of which there is disposed a guide roller 23 which is contact with the machined milling cutter 4 and opposed to which on the opposite side of the machined milling cutter 4 and in contact therewith is a pressure roller 26 positioned adjacent an axle 24 carried on one arm of a lever 25 in the other arm of which there is mon-'.,-t".-:4 spring 27 and a regulating screw 28 of a sensox 29 for positional measurement and which is connec41---.d to a system 61 for active checking of the machined size of milling cutter.

on the frame 1 there is rigidly mounted a hydraulic cylinder 30 having a piston rod 31 which can act on the lever 25. A system 60 for automatic control of the grinding power is electrically connected to electric motors 37 and 45 which rotate the grinding spindles 35 and 43, to the system 61 for active checking of machine size and to the DC high-torque electric motor 52.

The arrangement which has now been described is operated to carry out two-sided face grinding of cutting of milling cutters as follows:

A command signal is first supplied to-the hydraulic cylinder 30 to effect actuation thereof.

The piston rod 31 presses on one arm of the lever 25, overcomes the force of spring 27 and moves the pressure roller 26 away from the guide roller 23. The milling cutter 4 to be machined is secured to the mandrel 19 for radial locating and then a command signal is provided for return of the piston 31 to its initial position.

A command signal is then supplied for the commencement of a semiautomatic working cycle whereupon the piston 11 of the hydraulic cylinder 9 is moved forward and, by means of the piston rod 13, the clamp 12 and the fixators 18, there is effected motion of the slide device 17 towards the immovable grinding head 33. There is thus achieved a positioning of the machined milling cutter 4 to the face of grinding disc 36, the piston 11 being in contact with the piston 7 for this purpose. A command signal for rotation of the is grinding discs 36 and 44 and the machined milling cutter is then supplied. The command signal also actuates motion of the hydraulic cylinder 47 with respect to the piston 48 whereupon the slide device 41 associated with the displaceable grinding head 40 is quickly moved forward and positioned in a preset position. After a predetermined time set by a time relay, a command signal leads to release of slide 17 of carriage 3 under the action of piston rod 15 and wedge 16, and the release of the fixators 18. A command signal is then supplied to the mechanism 5 for the compensation of allowance of grinding of the machined milling cutter 4, and as a result the hydraulic cylinder 6 is connected with a reservoir for hydraulic fluid and under the action of pressure exerted by piston 11, piston 7 travels until it makes contact with the adjustable stop 8. A command signal for effecting grinding is now supplied whereupon the drive screw 50 is driven by the DC high-torque electric motor 52 through reduction gear 51, clutch 54 and nut 49. The motor 52 is controlled by the system 60 for automatic regulation of the grinding power, which system is connected to the system 61 for active checking of machined size, whereupon the following working operations are effected: rapid feed until the grinding disc 44 touches the machined milling cutter 4; rough grinding and fine grinding. The cam 58 of the mechanism within the housing 55 achieves compensation for the wear of the grinding discs 36 and 44 and is rotated up to the stop 56 where it remains in a fixed location with respect to the output shaft 53. A command signal is supplied from the system 61 for active checking of machined size to indicate the end of the working feed whereupon the hydraulic cylinder 47 is actuated to return the slider device 41 to its initial position. At the same time, the hydraulic cylinder 14 is of the mechanism for compensation of wear of the grinding disc 10 is returned to its initial position. This results in the slider device 17 being attached to the piston rod of piston 11. A command signal is given for the return of the piston of hydraulic cylinder 9 to its initial position. This results in movement of the slider device 17, including a stroke of the mechanism 5 for the compensation of allowance for grinding. A command signal is supplied to the DC high-torque electric motor 52 for the return of the slider device 41 of the displaceable grinding head 40 away from the machined milling cutter 4 and for a correction for the compensation of wear of grinding discs 36 and 44 by means of mechanism 55 whose friction disc with cam 58 is rotated together with the output shaft of the reduction gear 51 until the limit stop 57 is actuated. This marks the end of one operating cycle.

2 1

Claims

Claims:

1. An arrangement for two-sided face grinding of cutting-off milling cuttersi which comprises two grinding heads for acting on opposite faces of a said cuter, one grinding head being fixed with respect to linear displacement and the other being capable of linear displacement, both being capable of angular displacement, the grinding heads each having associated therewith an electric motor connected to a system for active checking of the machined size of the cutting-off milling cutter, which system is associated with a mechanism for compensating for the wear of both grinding heads and with a mechanism for incorporating for the allowance for grinding.

is

2. An arrangement for two-sided face grinding of cutting-off milling cutters which comprises a workpiece support and a grinding head provided on either side thereof, each having an associated motor for rotating a grinding head spindle and being electrically connected to a system for automatic regulation of the feed and a system for active checking of the machined size of the cutting-off milling cutter, one grinding head being incapable of linear displacement and the other being linearly displaceable in a housing in which there is disposed a slider device carrying a support on which angular adjustment of rotation of the other grinding head is effected, to which slider device there is rigidly attached a hydraulic cylinder for achieving a rapid positioning stroke and having a piston coupled to a drive therefor disposed in a housing in which there is rigidly secured a mechanism for compensating for the wear of both grinding discs, and wherein the support means for radial locating of the machined milling cutter is disposed between the grinding heads, being rigidly mounted on a slider device seated in a housing of a positioning carriage, in which housing there is disposed a mechanism for compensating for the allowance for grinding which is operatively associated with a mechanism for compensating for wear of the grinding disc, there additionally being mounted rigidly on that slider device to which the radial locating means is secured a support carrying a motor for driving a guide roller which is to be in contact with the machined milling cutter and which is opposed to a pressure is roller which is juxtaposed with respect to a lever which can act thereon and which is connected by nzeans of a sensor for linear measurement to the system for active checking of machined size of cutting-off milling cutter.

3. An arrangement as claimed in claim 2 for two- sided face grinding, including a mechanism for compensating for allowance of grinding comprises in preferred practice a single acting hydraulic cylinder with piston having an adjustable s,-3sociated therewith, the single acting hydraulic cylinder being rigidly secured to a second hydraulic cylinder comprised by the mechanism for compensation of wear of the grinding disc of the fixed grinding head, the second hydraulic cylinder having a piston rod which is rigidly connected to a cramp to which there is rigidly secured a third hydraulic cylinder with piston rod pivotally connected to a wedge-shaped device which is held to secure a frictional connection between the slider device on which the radial locating means for the machined milling cutter is located and the cramp.

4. An arrangement for two-sided face grinding of cutting-off milling cutters, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

Published 1990 atThe Patent Office. State House. 66,71 High Holborn, LondonWC1R 4T.D. Further copies maybe obtainedfrom ThePatentOllIce. Seles Branch, St Mary Cray, Orpington, Kent BM5 3RD. Printed by Multiplex techniques ltd, St Mary Gray, Kent, Con. 1187 i-, C