EP1208945B1 - Method of making an abrasive tool - Google Patents

Abstract

In a process to apply abrasive particles to a tool the particles are bonded to the tool surface by adhesive droplets. The droplets are dispensed from a micro-dosing system through a jet in a quasi-continuous process. The speed of tool movement and the droplet intervals are adjustable. Following the application of the adhesive droplet, adhesive particles are sprinkled on to the tool surface. Non-bonded particles are then removed.

Description

The present invention relates to a method for Production of abrasive tools according to the preamble of the claim 1. An example of such a procedure is known from US-A-5 832 360.

In the production of high-precision abrasive tools such as Dressing tools, it is important that the critical points, in particular Tool edges or profile tips, are occupied with grains, otherwise at Dressing an error is generated on the grinding tool that is in disadvantageously transfers to the workpieces to be processed. To the To be able to achieve required accuracy, for example, hard-material grains set by hand. This achieves the desired accuracy, the setting by hand is very time and labor intensive and therefore very expensive.

Methods are also known in which setting by hand were replaced by machine methods, so that the production of such Tools can be run faster and cheaper. From US-A-5 832 360, for example, a method is known in which trained on the carrier material as a perforated plate trained Sieve is placed, through which with the help of a squeegee, the solder paste is pressed. Thereafter, hard particles are scattered on the perforated plate and The perforated plate is lifted off carefully. The hard particles that are on a Solder paste point fell, stick there too and become at anchored there subsequent soldering process.

This method is especially suitable for flat and slightly curved Surfaces. Furthermore, for different sizes of corresponding templates are used for the area to be occupied, which complicates the process.

Another method is known from US-A-6 039 641, in which single-layer abrasive coverings in the so-called "greentape" method getting produced. For this purpose, a doughy solder paste on a desired Thick rolled and then a stencil that is thinner than the average grain size is placed on the not yet dried solder paste. The Hard material particles are scattered on the template, the template with the on it is removed grains again. The through the holes of Template in the solder paste fallen grains are pressed into this, then they are applied as a "greentape" on a base and soldered.

This method is also primarily for covering flat support surfaces suitable.

From CH-A-644 295 a method is known in which First, a photosensitive electroplating protective coating on the substrate is applied. Thereafter, this protective varnish is replaced by a mask containing the Contains structure of the later particle coating, through-exposed and dried. The unexposed areas are washed out and it remains a structured electroplating protective varnish will adhere to the substrate that supports the Function of a template takes over. Subsequently, on the carrier Particles are electrodeposited and finally the galvanic protective lacquer chemically removed.

With this method can not single grains but only so-called grain clusters are deposited. In addition, this procedure consuming, because always first a mask must be created. This too Method is especially suitable for flat surfaces.

The object of the present invention is now a method to create with which hard material particles on a support with a defined Distribution can be applied, this being simple and inexpensive to be possible, and wherein the carrier is a virtually arbitrary Form may have.

According to the invention, the solution of this problem by the im Claim 1 listed features.

Due to the possibility of relative movement between the carrier and the nozzle of the microdosing in virtually any track and with any Speed profile can be treated with a carrier may have more or less any surface shape.

An advantageous embodiment of the method is that the size of the droplets by changing the diameter of the outlet nozzle can be adjusted, whereby the size of the droplets to the Grain size of the hard particles can be adjusted, but also it is made possible that several grains can adhere per droplet and form a so-called grain cluster.

In addition to the setting of the speed, by means of which the outlet nozzle of the microdosing system and the carrier moves relative to each other can also be set, the frequency of ejecting the adhesive droplets so that the spacing of the individual adhesive droplets from each other can be preset.

The scattering of the provided with adhesive droplets carrier with The hard material particles can be carried out with a vibrating table, the spreading but can also be performed by an electrostatic scattering system be in which the hard particles scattered against gravity become. These are aligned in their longitudinal axis.

Advantageously, an adhesive is used which hardens can be. This ensures that the hard particles in optimal Way and in a short time firmly connected to the carrier.

An advantageous embodiment of the invention is that on the with the adhesive droplets and the adhering hard particles Provided carrier an additional adhesive layer is applied. Thereby an optimal connection between carrier and hard material particles is obtained.

Advantageously, the compound of the hard material particles with soldered to the wearer, if the material condition allows. This can be done by the carrier before applying the Adhesive droplets are coated with a solder paste, which then dry is left, but the solder paste can also after applying the Adhesive droplets and the sprinkling of the hard particles and the Curing the adhesive applied and dried, causing is achieved for example by spraying. After that, the so treated Carrier pushed into a high vacuum oven, where the soldering is performed. This gives an optimal connection between hard particles and Carrier, which also ensures a large grain supernatant.

An embodiment of the inventive method is explained in more detail by way of example with reference to the accompanying drawings.

Fig. 1 in schematischer räumlicher Darstellung ein Mikrodosiersystem, mit welchem auf einen als Rotationskörper ausgebildeten Träger die Klebstofftröpfchen aufgebracht werden;

Fig. 2 die Anordnung gemäss Fig 1, mit einer elektrostatischen Streueinrichtung für die Hartstoffpartikel;

Fig. 3 in schematischer Darstellung das Mikrodosiersystem, mit welchem die Flankenfläche einer Schleifscheibe mit Klebstofftropfchen versehen wird,

Fig. 4 in schematischer Darstellung das Mikrodosiersystem, mit welchem die Stirnfläche einer Schleifscheibe mit Klebstofftröpfchen versehen wird;

Fig 5a bis 5c die Darstellung einer einschichtig galvanisch belegten Umfangsschleifscheibe; und

Fig. 6a bis 6c die Darstellung einer gelöteten Umfangsschleifscheibe mit erfindungsgemäss plazierten Schleifkornern

It shows

1 shows a schematic, three-dimensional representation of a microdosing system with which the adhesive droplets are applied to a carrier designed as a rotary body;

FIG. 2 shows the arrangement according to FIG. 1 with an electrostatic scattering device for the hard material particles; FIG.

3 is a schematic representation of the microdosing system with which the flank surface of a grinding wheel is provided with drops of glue.

4 is a schematic representation of the microdosing system with which the end face of a grinding wheel is provided with adhesive droplets;

5a to 5c, the representation of a single-layer electroplated peripheral grinding wheel; and

6a to 6c show the representation of a soldered peripheral grinding wheel with abrasive grains placed according to the invention

In Fig. 1, a carrier 1 can be seen, which is formed as a sleeve blank is and from which a grinding tool is created. This sleeve blank 1 is in known, not shown manner clamped in a machine, which allows this sleeve blank with constant, adjustable rotation speed rotates. In this machine, a Mikrodosiersystem 2 is attached. This micro-dosing system 2 allows an adhesive from a Container 3 is conveyed in a nozzle head 4, which drops the adhesive dropletwise from an outlet nozzle 5 outputs. Such microdosing are known and usually work with a piezoelectric head, with which the droplets are ejected. Such microdosing allow the ejection of drops of glue, depending on the diameter the nozzle has a diameter in the range of 30 microns to 100 Micrometer can have. The ejection frequency of droplets from this Microdosing system is a maximum of 2000 droplets per second. This frequency is adjustable, usually with a frequency of about 500 to Worked 1000 droplets per second.

This microdosing 2 is so on the machine, not shown arranged that the outlet nozzle 5 in the direction of the axis of rotation of the sleeve blank. At the same time, this outlet nozzle also in the other two perpendicular directions traversable.

For applying the adhesive droplets 6 of the sleeve blank 1 in Rotation offset, the micro-dosing system 2 is adjusted so that the distance the outlet nozzle 5 from the tube blank 1 is about 0.5 mm, the microdosing 2 is moved along the axis of rotation of the sleeve blank 1, during which the glue drops are dispensed. This will be these drops of glue with a constant distance from each other on the surface the sleeve blank 1 applied. With appropriate monitoring equipment The output can be controlled by adhesive droplets, so this only takes place when the tube blank 1 is located below the outlet nozzle 5.

By changing the speed at which the sleeve blank 1 rotates, the feed rate of the microdosing 2 and the frequency the droplet output can be the glue points in different ways Apply structures to the support 1, in the present case as a sleeve blank is trained.

Immediately after the application of the glue dots are on the still rotating sleeve blank the hard material particles, for example by means of a Vibrating table, not shown, scattered. These hard particles can be used for Example CBN or diamond. The grain diameter of these hard particles ranges between 40 microns and 1000 microns. Depending on size the grain and the glue dot diameter remain one or more Stick grains at an adhesive point. The not on a glue point 6 impinging hard particles bounce on the surface of the tube blank. 1 down and fall down.

On the tube blank 1 with the attached hard particles is applied a solder paste. This is done here in a known manner with an airbrush gun The sleeve blank thus provided with the solder paste can at the Air or be dried with a hot air dryer. Then he arrives Tube blank in a high vacuum oven, in which at a temperature from about 720 ° C to 1000 ° C the soldering takes place, causing the hard particles be firmly connected to the sleeve blank.

In the example described here, an adhesive was used which hardens under the influence of UV light. It would also be conceivable to use a Adhesive that is infrared curing. Optionally, there is also an adhesive suitable, which is selbstaushartend. In addition, the glue, if a soldering takes place, also suitable for vacuum.

Instead of using a vibration table to sprinkle the Hard material particles can also, as can be seen from Fig. 2, an electrostatic Spreader 7 be used Here are the hard particles on a Conveyor belt 8 under the action of an electric field between Conveyor belt 8 and sleeve blank is produced in a known manner, against the Gravity scattered, the hard particles, with one on the sleeve blank 1 applied adhesive droplets come into contact 6, stick, the others fall behind. With this type of scattering the hard particles are aligned in their longitudinal axis and remain so adhere, the grain supernatant will be improved. Of course, other methods for scattering the particles on the carrier or the adhesive droplets conceivable.

In Fig 3 is shown, such as a flank surface of a Peripheral grinding wheel treated according to the inventive method can be. The axis about which the clamped carrier 1 rotates, is rotated by 90 ° compared to the previously described examples. The outlet nozzle 5 of the microdosing system 2 is the width of the flank surface moved towards and away from the axis of rotation. This will be the adhesive droplets 6 practically on a zigzag line on this flank surface applied, this is then as previously described with hard particles sprinkled and treated accordingly.

In Fig. 4, the peripheral surface of the peripheral grinding wheel is treated. In this case, the axis about which the carrier 1 rotates again equidistant as shown in Figs. 1 and 2. The microdosing system 2 leads a reciprocating motion that is aligned parallel to the axis of rotation is, wherein the travel of the width of the resulting peripheral grinding wheel corresponds Again, the adhesive droplets 6 below sprinkled with hard particles, the treatment takes place, as in the first Embodiment.

The structuring is also possible with the latter two examples the applied adhesive droplets 6 by changing the rotational speed, the reciprocation of the microdosing system 2 and the frequency of the dispensing of the adhesive droplets.

From the pictures 5a to 5c is a single-layer electroplated Peripheral grinding disc visible. In particular from FIG. 5c it can be seen that that the grain supernatant a is relatively small, and that the distance b of the grains each other is also low and uneven.

In contrast, as is apparent from Figs. 6a to 6c, the Kornuberstand a with the inventive method very large, the distance b of the hard grains 8 from each other is larger and substantially constant.

As can be seen from the previously described examples, can the carrier 1, which treated according to the inventive method becomes, have the form of a rotation body. The to be treated Surface can have any shape, it can also be flat. The carrier may be made of any material, such as metal or ceramics. The method according to the invention can also be used Producing abrasive belts, wherein the carrier be any solid material can, such as paper, textile fabric or films of metal, ceramics or plastic.

The hard particles applied to the carrier can also consist of a virtually arbitrary material, such as diamond, CBN, any kind of ceramics, tungsten carbide, titanium carbide or carbide and their mixtures.

The particle sizes of the hard particles used depend on the Type of application of the abrasive tool produced from the diameter of this For example, grains are in the range of 2 microns to 2 millimeters. It is also conceivable that depend more adhesive particles per adhesive droplets remain, whereby a so-called grain cluster are formed. Thereby a particularly good attitude is achieved, since the individual grains during the labor input can repell each other.

The soldering process to which the particulate carrier is exposed can, as described, carried out in a high vacuum oven Of course, this can also be done by soldering, brazing or Soldering under inert gas done.

The properties of the adhesive used are those used Materials of the carrier and the particles adapted. For some use cases no additional attachment of the particles to the carrier is required, for certain materials, applying an additional, curable adhesive layer, with some materials and certain Applications, a soldering treatment is appropriate.

Claims (11)

1. Method of producing abrasive tools in which hard material particles (9) are applied on a substrate (1) by an adhesive being applied to the substrate (1) on which the hard material particles (9) are put and remain adhered, the putting on taking place with a defined distribution, characterised in that the application of the adhesive takes place in the form of droplets (6), which are dispensed substantially continuously onto the substrate (1) through a discharge nozzle (5) of a micro-dosing system (2), and the substrate (1) and the micro-dosing system (2) with adjustable path and velocity profile being moved relative to one another, and in that subsequently the hard material particles (9) are sprinkled on the substrate (1), provided with the adhesive droplets (6), and only the hard material particles which come into contact with an adhesive droplet remain adhered on the substrate, whereupon the non-adhering hard material particles are removed.
2. Method according to claim 1, characterised in that the size of the droplets (6) is adjusted through modification of the diameter of the discharge nozzle (5).
3. Method according to claim 1 or 2, characterised in that the frequency of discharge of the adhesive droplets (6) is adjusted.
4. Method according to one of the claims 1 to 3, characterised in that the besprinkling of the substrate (1), provided with adhesive droplets (6), with the hard material particles (9) is carried out using a bench jolter.
5. Method according to one of the claims 1 to 3, characterised in that the besprinkling of the substrate (1), provided with adhesive droplets (6), with the hard material particles (9) is carried out using an electrostatic scattering facility (7), whereby the hard material particles (9) are scattered against the gravitational force.
6. Method according to one of the claims 1 to 5, characterised in that the substrate (1) provided with hard material particles (9) undergoes a procedure in which the adhesive is hardened.
7. Method according to one of the claims 1 to 6, characterised in that applied to the substrate (1) provided with the adhesive droplets (6) and the hard material particles (6) adhering thereon is an additional adhesive coating.
8. Method according to one of the claims 1 to 7, characterised in that prior to the application of the adhesive droplets (6) the substrate (1) is provided with a soldering material layer.
9. Method according to one of the claims 1 to 8, characterised in that the substrate (1) provided with the adhesive droplets (9) and the hard material particles (9) adhering thereon is coated with a solder paste and dried.
10. Method according to claim 9, characterised in that the solder paste is sprayed on with an airbrush pistol.
11. Method according to one of the claims 8 to 10, characterised in that the substrate (1) provided with the soldering material and hard material particles (9) undergoes a soldering procedure.

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