JPS591141A - Method and device for grinding flat surface - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The mechanical grinding of metallic and non-metallic materials by grinding is increasingly being adopted in manufacturing technology, with two development goals being achieved: on the one hand, higher precision and surface The aim is to achieve high quality on the one hand and increase machining efficiency on the other hand. Both goals have so far been unrelated to each other. This is because, according to the current state of technology, the configuration of the machine, and in particular the specifications of the grinding tool, must be specially designed to achieve one or the other optimum.

Currently, two grinding methods are known: "circumferential grinding" and "face grinding". "Circumferential grinding" is more developed than "face grinding" and can already partially compete with turning, milling and planing in terms of machining efficiency and precision. Both different grinding methods according to the known technology are described in detail in the technical literature, the efficiency limits being stated in academic research papers, specialized literature and production information and reflecting the final state achieved in each case. are doing. Both of the above grinding methods have their own partially covering range of use in which they work optimally. In that case, for very hard, brittle and sensitive materials and very smooth planes, face grinding methods are conceivable. Such materials are in particular non-metallic materials which are used in large quantities in the form of disks or rings, for example as substrates for electronic components or packing reservoirs. - An example is the machining of very thin disks made of silicon, germanium, quartz, sapphire and ■-V-bonds, which are used as base frames for the production of electronic components and whose volumes are increasing significantly. It is. Lapping, which was initially used exclusively for surface machining, is increasingly being replaced by grinding with diamond-coated grinding discs.

This method has been developed by the applicant for use in manufacturing.

The invention is based on the problem of finding a method and a device for carrying out this method by which very sensitive parts of brittle and often extremely hard materials can be surface ground. In this case, the main requirement is a machining efficiency that far exceeds that of the known technology in material-saving material cutting, with the unavoidable changes in the uppermost material layer during the cutting process and the resulting fracture depth. should be even less than currently known and used cutting methods, and at the same time provide a substantial improvement of the ground surface with respect to smoothness, roughing depth and material damage (crystal lattice disruption). achieve.

Another goal is to improve the measurement accuracy and the surface quality in order to reduce the number of back and forth working steps required in the case of the materials mentioned, such as, for example, rough grinding, fine grinding and fine grinding.

Furthermore, when machining workpieces consisting of brittle, brittle and often extremely hard materials, improved machining efficiency compared to known techniques is also possible with workpiece-saving material cutting. objective, in which case the unavoidable changes in the uppermost material layer during the cutting process and the resulting fracture depth must be less than currently known and used cutting methods, and at the same time, e.g. grinding,
An improvement in surface quality is achieved in order to reduce some of the back-and-forth working steps required in the case of said materials, such as finish grinding and fine grinding.

The brittle and fragile materials processed according to the invention have a minimum Vickers hardness of 50 ON/mm, in particular 700 ON/mm.
-2500ON/mm2. It is a vessel made of such materials. A particularly advantageous group of materials is the AI-BV bond with a Vickers hardness of 8500 t and a hardness of 7 (l U
ferrite having a Vickers hardness of up to 7
germanium with a Vickers hardness of up to 500, silicon with a Vickers hardness of up to 11,500, and 1
Spinel with a Vickers hardness of up to 4000 and 19
Sapphire and gallium-gadolinium garnet (G
GG). Such materials are particularly advantageously used in electronics. The material that is more problematic is 15
Silicon carbide SIC has a Vickers hardness of 000 to 25,500, silicon nitride 813N4 has a Vickers hardness of 15,000 to 20,000 (35,000 when it is a single crystal), and carbide has a Vickers hardness of 22,500 to 31,000. It is boron B4C. Such materials are used in machine construction, motor construction and equipment construction. Another convenient group of materials includes 17,000-2
It contains a milled ceramic with a Vickers hardness of up to 8,500° and corundum A 203 with a Vickers hardness of 21,500. These materials serve as non-metallic cutting materials. Furthermore, each 800ON/r11
Ceramic resonators, quartz crystals and porcelain with Vickers hardness up to r112 come into question.

All grinding machines used so far operate in the classical manner, so-called face grinding, in which three movements are necessary to achieve the required machining and the required surface quality. That is, (1) the cutting speed of the abrasive grains generated by the rotation of the grinding disk; (2) the feed motion that is the relative movement between the workpiece and the grinding disk parallel to the grinding coating plane; (3) An infeed movement is required in the direction of the axis of the grinding disk perpendicular to the surface of the workpiece to be ground. In the case of face grinding, the material is removed almost exclusively at the outer grinding disc edge. As the grinding disk advances over the workpiece, the machined area, which can be seen as steps in the workpiece, moves around over its entire surface, along with the feed rate. Compared to all the cutting-capable abrasive grains present on the grinding disc surface, a very small number of abrasive grains on the outer grinding disc rim perform the entire workpiece cutting during the use of the grinding disc. must be accepted.

The chip space present around the abrasive grain for evacuation of the abrasive material is likewise very limited, which imposes two critical limitations on increasing machining efficiency.

According to the invention, υ, contrary to theoretical ideas and practical experience of total transport, we propose that the new method still has only two motion components. According to the invention, it should be noted that during the grinding process, the cutting speed of the abrasive grains generated by the rotating grinding disc and the infeed movement of the grinding disc oriented perpendicularly to the workpiece surface to be ground are All we need is forward movement. In the case of classical grinding, the feed motion is taken as the dominant method parameter;
This eliminates the need for feeding movements, which all known and highly valuable grinding machines also have very expensive and flexible adjusting devices.

Since the grinding process in the case of the method according to the invention consists in sinking the rotating grinding disk into the surface of the workpiece, the name "sinking grinding" is proposed for the method according to the invention. In this case, the grinding coating is especially dimensioned in such a way that the entire surface of the workpiece to be ground is covered, but if the workpiece is very spread out, repeated partial subsidence grinding is possible, and In this case, after each subsidence grinding, the work piece is displaced by the covering width relative to the axis of the grinding disc.

The method according to the invention surprisingly works well in the case of hard and brittle materials prone to crystal lattice disruption on the processed surface.
Very good machining behavior. Thus, the machining efficiency is several times greater than the values known today. This can be demonstrated from the fact that in the method according to the invention, all the abrasive grains present on the surface of the grinding disk participate in the machining. The chip size and cutting forces of the individual abrasive grains are kept smaller even though the total machining is several times larger.

Measurements have confirmed that the adverse changes in the crystal lattice of the workpiece on the grinding surface are relatively small compared to known grinding methods.

A relatively fine-grained grinding disc achieves machining efficiencies that could only be achieved with very coarse-grained roughing discs of this size, while preserving the smooth workpiece surface characteristic of fine-grained grinding discs. Remains sagging or even noticeably improves. The smoothness and the roughening depth can still be substantially modified if, after the end of the infeed in "sink grinding", the workpiece is withdrawn from the working area parallel to the surface of the grinding disc.
Traces of abrasive grain tips that protrude slightly further from the grinding disc coating are averaged out. This additional working means can be compared in a significantly simplified form to the so-called "sparking aubi."

The advantages of the new grinding technology according to the invention are numerous: Since there are no feed movements during machining, a simple and very stable machine construction is possible. In known automatic single-station or multi-station grinding machines, a circular chisel serves as a workpiece carrier and as a workpiece feeder for generating variable feed rates with conditional increases in the outward direction. This drawback, which negatively affects the surface quality and material distortion during the action of the abrasive grains, is eliminated.

This is because the final sparking that is carried out each time
This is because it can actually maintain a very fine and uniform surface as a linear movement of the grinding spindle stock.The conventional circular chiffle grinding automatic machine with multiple stations is capable of grinding, fine grinding, All grinding stations have the same feed rate, regardless of whether they are performing fine grinding or not.In the device according to the invention, where no feed movement takes place during the grinding process, a "sparking-a-F movement" is carried out each time. It can be adapted laterally and optimally with little mechanical outlay, with only a linear "sparking-out movement" being required for the entire transport at the last grinding station 7. During the grinding operation according to the invention, the workpiece carrier, for example in the form of a periodically advancing circular chiffle, is stationary, so that a very precise and easy-to-manipulate workpiece loading and unloading is provided. Another advantage is that during this period a complete spatial separation between the grinding area and the charging and unloading area is possible, which is very significant in the case of high-precision workpieces. . This is because, when placing the next piece to be processed,
This is because the work piece loading station can be cleaned and kept clean.

The present invention provides the significant advantage of several times higher machining efficiency with relatively little workpiece and tool distortion. This makes it possible to grind brittle materials even to very thin thicknesses. This is because the crystal lattice of the material is advantageously changed only slightly. Another advantage is that during the grinding operation according to the invention, the work carrier chifur rests directly on the machine stand in a tightly locked manner and is therefore very vibration-stable.

Another advantage of the invention is that the inherent tooling costs are low due to the long service life of the grinding disc, which, in addition, is driven by the participation of a maximum number of grinding grains in the grinding process. This reduces the abrasive load and achieves chip removal. In this case, the constant, low-vibration cutting force acting on the individual abrasive grains can be expressed as a spatially fixed vector with respect to the grinding surface. Due to the proviso that no feed movement is required in the present invention, once the grinding object is released from its connection.

is suppressed.

The grinding disk required for the method according to the invention is simple and easy to manufacture. It is customary to fasten the abrasive body, in particular with diamond abrasive grains as cutting material, to the base body in the form of a disk, plate or strip. The intermediate spaces between the individual grinding elements, which are then left open, increase the cooling effect and facilitate chip ejection.

In that case, the distance between the individual grinding elements or grinding segments is in each case 9 smaller than the surface to be machined. In this way, when the workpiece is inserted between the grinding segments and the grinding disk is rotated, it is avoided that the conventional face-grinding process, in which only the edges of the grinding segments are active, takes place. However, grinding discs with a through sheath whose dimensions are matched to the size of the workpiece can also be used advantageously.

When grinding according to the present invention, an economical fine grain size range can be used, which results in smooth surfaces when grinding non-metallic materials.

In the following, advantageous embodiments of the invention will be explained in detail.

The embodiment of the device for carrying out the method according to the invention, shown in FIG. A movable table 2' is supported for receiving and further transporting the workpiece 3, and the table 2 can be clamped tightly during the grinding process. The workpiece support projects partially from a support 4, on which is mounted a grinding spindle 5 carrying a grinding disk 6 with a grinding surface 7 directed toward the workpiece, and a drive motor 8. There is. A support 4 is mounted 9 on the stand 1 with precision rigid guide elements 9 so as to be movable vertically up and down. This vertical up-and-down movement can be achieved, for example, by an electrically driven infeed spindle 1.
It can start with 0. This feeding and rapid return movement lifts the entire support upward. During this return movement of the support, by rotating the table 2 periodically or moving it horizontally, the machined workpiece is removed from the area of the grinding disk and at the same time the new workpiece to be machined is removed. Bring the piece under the grinding disc and position it in working position. This simultaneous loading and unloading takes place in unison with the return movement of the support, so that unless the transfer movement ends and the workpiece carrier is tightened again, a collision between the new workpiece and the grinding disc will occur. No.

FIG. 2 illustrates a grinding disk for carrying out the method according to the invention. The illustrated grinding disk 40 has a grinding surface 42 directed toward the workpiece 41, which grinds the workpiece 41, which is firmly positioned during the grinding process and is not subjected to a feeding movement, to a surface surface. completely covered. In this way, it is ensured that during grinding all the grinding objects on the grinding surface 42 are available for cutting action.

FIG. 3 schematically shows the various possibilities of developing the grinding object surface that can be used according to the invention.

FIG. 3a shows the grinding surface formed by the grinding object pellet 43. FIG. FIGS. 3b and 30 show a grinding disk whose abrasive coating is formed by rectangular or trapezoidal abrasive coating elements 44,45. In FIGS. 3d and 3e, the grinding coating element is designed as a small bar 46 or as a circular arc 47. Although in all embodiments 3a to 3e each a circular workpiece 41 is depicted, it can be seen that the grinding coating effectively completely covers the workpiece on the surface. In each of these grinding disc embodiments, it is ensured that during the grinding process, all the grinding objects of the grinding covering element directed towards the workpiece become effective in cutting. This is clearly in contrast to conventional face grinding, where only the grinding objects at the edge of the grinding disk are active in the cut.

Another advantage of the method according to the invention is that the grinding force and the area of action of the grinding disk remain constant on the workpiece during the entire grinding time. A very uniform grinding section and a very stable grinding process are thereby achieved.

In the embodiment according to FIGS. 4 and 5, both processing stations 3.4 are mounted on the side 2 of the stand 1 or on the stand 1.
9 have been taken. The height of the cutting estuary can be adjusted by means of one vertical sliding guide 5a, 5b in each case. The height adjustment is performed by one electric motor 7a,
This is done by ball-spindle spindles 6a, 6b driven by ball screws 7b. The rotational speed of the electric motor and thus the height adjustment speed can in particular be adjusted electronically. The shifter 8 of the first processing station 3 is a unit with vertical guidance.

A horizontal shifter 9 of the second machining station 4 is supported longitudinally displaceably on a vertical slide 10, the guide 12 of which has a clamping device so that the jib 9 can be moved when the clamp is released. It can be moved by a linear motor 11.

All straight line guides 5a.

5b, 12 have very precise, hard and low friction guide tracks, the guide clearance of which can be adjusted. A measuring station 13 connected after the second machining station 4 monitors the thickness dimension of the workpiece 14 and performs a subsequent adjustment of the second grinding disk 15b. Each processing station 3.
On its front side, Shib 4 accommodates a vertically mounted grinding spindle 16,17. Grinding spindle motors 18, 19 are mounted on the rear side with flanges.

The force is transmitted from the spindle motor to the grinding spindle by means of a flat belt drive 20. The rotational speed of the grinding spindle can be adapted to the particular grinding task by changing the speed ratio of the belt drive or by electrically adjusting the rotational speed of the spindle motor 18, 19.

Depending on the implementation, the grinding spindle is supported on roller bearings or air bearing elements. At the other end of the spindle shaft, a grinding disk flange is seated in a conical receiver, and this grinding disk flange carries a grinding disk tsa, 15b. A circular table 21 is supported in the center of the stand 1. The rotary table 21 has several workpiece gripping points depending on the size of the workpiece. This is easy to remove and replace by releasing the fixing screw. Depending on the material to be processed, the workpiece 14
grip electromagnetically or by vacuum. The introduction of the electrical energy or air supply at the gripping point takes place via a hole 29 in the center of the rotary table. The processed piece 14 is
The circular chiffle 21 periodically transports it from the charging station 23 to the first and second processing stations and back to the unloading station 24.

Roller bearings 38 take over the radial guidance of the round tip 21. A circular track 30 formed on the top surface of the stand acts as an axial guide. This sliding trajectory has, for example, low friction and stick-slip
A small synthetic resin coating with l ip) is provided, and lubricating oil is supplied in pulses from a central lubricating section located on the stand. As long as the grinding discs 15a and 15b are working, the circular chifur 21 is stationary and the circular chifur 3
Tightening elements 31a, 31b arranged symmetrically around 20
By being pressed against the axial bearing 30 of the stand,
During grinding, the circular chiffle and therefore the work piece can be supported absolutely without any gaps, very strongly and without vibration.

At the end of each grinding cycle, after the disk is lifted upwards,
The circle chiful is further moved periodically as follows. That is, for example, an electrical or hydraulic rotary drive 33-
The drive pinion 34, which meshes with a gear 35 which is rigidly coupled to the circular chifurle 21 and the circular chifural shaft 32, rotates until a cutoff pulse is emitted from the chifural limit switch, and the cutoff pulse is emitted. This is the case when the new cutting wheel 1 rotates further until it reaches the bottom of the grinding disk.

For accurate positioning, an indexing member 36 is additionally provided.
Similarly, it engages a partial disk 37 which is rigidly connected to the circular full shaft. Thus, after all the progresses have been made, the circular chiffle is very precisely and immovably fixed in its working position on the grinding station. However, other structural solutions can be used in its various implementations, such as, for example, a radial serration of the crank device 1 in order to continue advancing and locking the circular tip.

For all experts, the question here is “structural”
J-ability is well known.

Opposite the processing station 3.4, machine stand 1
On the front side there is a charging station 23 on the left and an unloading station 24 on the right. Loading and unloading takes place during the grinding time in processing stations 1 and 2 facing each other. In the case of loading, the workpiece is lifted from the magazine 26 by the rotatable gripping arm 25a or from a suitable workpiece holder from the stand and swiveled over the rotary table and placed on the workpiece clamping plate 22. Removal is performed in reverse order. Clean the workpiece clamping board between the loading and unloading stations. The purifying station 27, with its rotating synthetic resin black, removes the grinding material that is still present in some areas and assists the water jet exiting from the nozzle with the cleaning necessary for the subsequent charging. Create a supporting surface.

A screening member 28 above the center of the rotary table protects the loading and unloading area from contamination through the processing station.

The operation of the powerful grinding machine according to the present invention is as follows.

After the machine has been loaded in the above manner, the rotary table advances the workpiece under the first grinding station 7, the grinding disk of which is in an upper position corresponding to one method of measuring the workpiece. . After flattening and locking the round chiffle, the grinding disc is lowered into the workpiece from above, until finally the finishing dimensions of the first station are achieved. The grinding disk has now returned to its starting position. The grinding disc of the first grinding station is
The covering width of the grinding disc is designed such that it covers the entire workpiece or, during sinking, the entire surface of the workpiece is machined. The feeding speed of the grinding disk can be preselected steplessly. The rotary table then advances the workpiece to a second processing station, and the rotary table is again gripped and locked. The grinding process corresponds to that of the first machining station, but with fine-grained grinding discs and with fewer material cuts.

At the end of the infeed movement, it is advantageous to then pull the grinding disk outwards across the workpiece without infeed, analogous to a conventional "sparking out", in order to modify the surface.

A first dimension of the evaporator is measured during further progress to the unloading station. The height dimension of the second grinding station is automatically adjusted by the machine when the πF capacity limit on the grinder is reached due to wear of the grinding object. Unloading takes place in the reverse order of loading, with the workpiece being placed in the magazine again.

A new workpiece is placed or removed after every rotary table cycle, resulting in a continuous flow of workpieces through the grinding machine.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the apparatus of the present invention for carrying out the method according to the invention, and FIG. 2 shows the size relationship between the grinding surface of the grinding disk and the work piece in the apparatus according to FIG. 1. Figure 4 is a diagram schematically showing an advantageous development of the grinding surface of a grinding disk for carrying out the method according to the present invention in axle load ÷ casting 4 size. FIG. 5 is a front view of another embodiment of the device according to the invention; FIG. 5 is a plan view of the device according to FIG. 4; 2.21...Table 3.14.41...Workpiece 5, 16.17...9 Grinding spindle 6, 15a, 15b, 40 m Grinding disk 7...
・Grinded surface 273 Western style drawing (no internal changes) JP-A-1859-1141 (8) FIc4.3a 11%, 3dFIGr
, 3bFIQ1.3 e -More Remains-"("辷J-, KA, E. August 3, 1937, Commissioner of the Japan Patent Office Kazuo Wakasugi, 1, Indication of the Case Showa J; 8th Year Patent Application No. gr/6/ No. 2, Title of the invention 3, Relationship with the case of the person making the amendment Applicant Gesell+) Futo Sto Be/Ulenkter Habsong 4, Agent (IF9? 2-8 Toramon, Minato-ku, Tokyo) Number 1 facing the bolt-throwing hill) [Telephone: 03 (502) 1476 (
Representative)] 5. Date of amendment order (DE) ■P 3218656.8 @ January 28, 1983 ■West Germany (DE) ■P 3302881.8

Claims (8)

[Claims] (1) A method of grinding a flat surface with a grinding disk having at least one flat grinding surface directed towards the flat surface to be ground and rotating about an axis perpendicular to the grinding surface. , during the grinding process, the only relative movement between the workpiece and the rotating grinding disk is an infeed of the grinding disk in the direction of the axis of rotation of the grinding spindle, with the workpiece preferably having a minimum Vickers hardness of 500 ON/ rlTn
A method characterized in that the material is made of a brittle and easily broken material having a . 2. The method of claim 1, wherein the flat grinding surface of the grinding disk effectively completely covers the surface of the workpiece to be machined. (3) Grinding a flat surface with a grinding disk having at least one flat grinding surface directed towards the flat surface to be ground and rotating about an axis perpendicular to this grinding surface. &During the grinding process, the only relative movement between the workpiece and the rotating grinding disc is the infeeding of the grinding disc in the direction of the axis of rotation of the grinding spindle, with the workpiece being particularly In an apparatus for carrying out the process, consisting of a brittle and fragile material with a hardness of 500 ON/inm2, a grinding spindle is arranged movably in the direction of the axis of rotation and, during the grinding process, the surface to be machined is operatively It is characterized in that the workpiece holder is equipped with a device for fixing the workpiece to be machined in the working area of the grinding disk, such that a particularly complete covering is achieved by the flat grinding surface of the grinding disk. device to do.゛ 4. Device according to claim 3, characterized in that the grinding disk is formed as a cup disk, the flat ring-shaped grinding surface completely covering the surface to be machined. (5) The grinding disk is formed as a cup disk, the flat grinding surface of which consists of a number of segments, the spacing between each segment being smaller than the surface to be machined. The device according to item 3. (6) having a number of machining stations attached to a common horizontal round table having a number of workpiece gripping devices, each of which has a vertically disposed and vertically movable grinding station; In an apparatus for surface surface grinding, in which a grinding spindle with a disc is provided, the grinding disc having a flat grinding surface directed towards the flat surface to be ground, a rotary table (21) is provided. Featured device. 7. Device according to claim 6, characterized in that the flat grinding surfaces of the grinding discs (15a, 15b) operatively completely cover the surface of the workpiece (14) to be machined. (8) There are two machining stations (3, 4), with the second machining station (4) being a horizontal jib.