EP3154745A1

EP3154745A1 - Grinding disk

Info

Publication number: EP3154745A1
Application number: EP15729392.9A
Authority: EP
Inventors: Bettina Davids; Enrico Kaminsky
Original assignee: Hermes Schleifkoerper GmbH and Co KG
Current assignee: Hermes Schleifmittel GmbH and Co KG
Priority date: 2014-06-10
Filing date: 2015-06-08
Publication date: 2017-04-19
Anticipated expiration: 2035-06-08
Also published as: EP3154745B1; HUE048741T2; EP2954981A1; WO2015189145A1; PL3154745T3

Abstract

The invention relates to a grinding disk having a grinding region (2) which is effective in the circumferential direction and comprises a bonded abrasive medium, and with reinforcing elements (3) which are not involved in the grinding operation. According to the invention, the reinforcing elements have at least one reinforcing washer (3) arranged at the end face, said washer comprising no abrasive medium and being dressable.

Description

grinding wheel

The invention relates to a grinding wheel having a circumferentially acting grinding area comprising bonded abrasive; and with non-participating in the grinding process reinforcing elements.

Abrasive-bonded abrasive tools have abrasives embedded in a binder which together form a compact body. The choice of suitable grinding tool depends on the task underlying the machining of the workpiece. Most here two processing effects are be prevailing ^¬ Lich: Firstly, the removal of material with the aim of geo ^¬ metric design and on the other hand, the microstructure of the machined workpiece surface. In the majority of Be ^¬ processing tasks to a geometrical shape obtained who ^¬, wherein both requirements are placed on the workpiece surface. The criterion for the condition of the workpiece surface is usually the surface roughness R _A. and the nature and orientation of structural features.

Deviating from this, however, there are also machining tasks with grinding tools, which have the goal of producing a particular microstructure of the workpiece surface predominantly or exclusively. For example, The stainless steel sheets for use in elevators or interior linings provided with a decorative line pattern, without any significant material removal takes place. Here, preferably non-woven or brushing tools are used because these ver ^¬ add a sufficient elasticity in order to fit flat against the workpiece. Such tools are coated abrasives.

In the area of bonded grinding tools, special constructions have been developed for the surface structuring of workpieces. In general, however, these are not large workpieces such as sheets, but predominantly functional parts of the area Maschi ^¬ nenbau. As in the field of abrasives on documents with the nonwoven and brushing tools here is the requirement of elasticity of the grinding tool to adapt to the surface contour of the workpiece. Accordingly soft and elastic Bin ^¬ means are used for such applications, such as rubber, silicone or polyurethane. It is also common to incorporate elastic solids such as cork.

A common application of such tools is the Be ^¬ processing cylindrical workpieces. This can be done both between peaks, but also without a center. In both

Cases comes the peripheral side of the grinding wheel for a ^{¬ handle} , with the axis of the workpiece and the axis of the grinding wheel behave parallel to each other. In order to machine the workpiece over the entire length, the grinding wheel moves in the axial direction and this usually ^¬ continuously in several cycles. Although this allows a uniform processing image in the desired rough However, the surface shows a spi ^¬ ralförmiges surface pattern, also referred to as "twist". This effect can be the functionality of the workpiece be ^¬ impair, such. As in cylinders or racks that are part of a hydraulic system and by

Move seals. The achieved roughness depths are approx. R _A <0.8 mm.

Alternatively, a similar process is carried out, except that the grinding tool does not move axially ver ^¬ continuously, but is separated from the workpiece after each engagement, moves and then again in the sense of a "plunge grinding ^¬" comes to engagement. However, the disadvantage here is the discontinuous process with the risk of producing markings with each intervention.

This effect can be avoided if also ground with the peripheral side, but the grinding wheel is aligned radially to the longitudinal axis of the workpiece and moves in this direction. The grinding wheel axis thus always behaves at right angles to the workpiece longitudinal axis. In this way, a straight, axially aligned upper ^¬ surface structure is obtained. Because generally curved surfaces are machined, the perimeter side is dressed according to the workpiece geometry. This makes it possible to edit almost the half-sided peripheral surface in one operation. The invention is based on the object to provide a grinding ^¬ disc of the type mentioned, which is is suitable for grinding with the peripheral side in particular for surface structuring and which allows the production of surfaces of high quality with little effort. This problem is solved by an aforementioned

Grinding wheel characterized in that the reinforcing elements we ^¬ least have a frontally arranged reinforcing disc, which is designed to be abrasive-free and dressable.

First, some terms used in the invention are explained.

The term grinding wheel in the context of the invention refers to a grinding tool with bonded abrasive, which is designed for machining surfaces with a narrow side or peripheral side. The abrasive area is derje ^¬ nige volume area of the grinding wheel that has the bonded abrasives, or contains. Suitable and within the framework of the invention usable abrasives are ^¬ example, silicon carbide, melting and sintered corundum. Very hard abrasives such as cubic boron nitride or diamond can be used, but there are the special features of this hard abrasive (high wear Schleißbeständigkeit) due to the relatively soft integration into the binder is usually not for Tra ^¬ gen.

The grinding area acts in the circumferential direction. This means that it can be ge ^¬ placed on a narrow side or peripheral side of the grinding disc ^¬ with the surface to be machined in contact. The grinding wheel according to the invention is preferably designed ^{kreisför ¬} mig and suitable for clamping on a rotary ^¬ grinding machine, but is not limited thereto. The grinding wheel does not have participating in the grinding process participating ^¬ ing reinforcing elements. These elements increase the mechanical stability of the disc and reduce insbeson ^¬ particular an elastic or plastic deformation of

Grinding wheel under the stresses occurring during grinding, such as centrifugal forces or pressure loads. Thus, they tend to reduce the inherent tendency of the bonded abrasives to deform under the stress of grinding. The characterization of the reinforcing elements as non participating loading indicated at the grinding process, that it does not advise in a conventional grinding with the surface of the machined workpiece in engagement ^¬ ge.

According to the invention it is provided that the elements have a Verstärkungsele- arranged at the end gain ^¬ disc least formed abrasive free and be dressed. Front side means that the at least one reinforcing disk is arranged on a surface of the grinding ^¬ disc, which is not the grinding peripheral surface. In a circular grinding wheel such an end face is usually perpendicular to the intended rotation axis.

The reinforcing disk is a flat element that absorbs and discharges mechanical

Serves forces and is not designed to participate in the Schleifvor ^¬ gang itself. It accordingly contains the materiality ^¬ union no abrasive. This reinforcement disk is dressable trained. The meaning and technical advantages of this feature will be explained below.

A frequent area of use of grinding wheels acting on the peripheral side is the surface structuring of curved, for example cylindrical surfaces. Prerequisites for this, however, are a sufficient elasticity of the grinding area and a high contact pressure. In this case, in the prior art, the grinding wheel can be deformed, as a result of which the positive connection with the workpiece is no longer present. On the other hand, the pressure and the associated deformation can lead to the formation of cracks and, as a consequence, to the destruction of the grinding wheel. From obvious prior use, it is already known to reduce these undesirable effects by the use of two lateral steel discs, which are mounted together with the grinding wheel on the spindle. However, this solution of the prior art is associated with considerable disadvantages.

After machining a number of workpieces, grinding wheels must be periodically dressed to restore, in particular, the desired surface geometry of the peripheral side. However, steel discs can not be dressed together with the grinding wheel. ^¬ much more steel washers must be fitted with a correspondingly reduced diameter after each dressing. This has the disadvantage of stockpiling and assembly work. It must also be taken into account that the steel discs are only available in certain graduations and thus can not be achieved a precisely fitting support effect. A particular advantage of the present invention is that the dressable trained reinforcing discs allow a comparable mechanical stabilization ever ^¬ but can be dressed together with the grinding area when dressing the grinding wheel. The necessary in the prior art disassembly / assembly of steel discs ent ^¬ falls.

Under a suitability for dressing processes will be understood that the geometric shape and / or the sharpness can be restored by means of ei ^¬ nes conventional dresser. Dressing tools of this type include embodiments with single diamonds or diamonds-occupied moldings, but also diamond-free dressing tools with silicon carbide or corundum.

According to the invention, it is particularly preferable that the have Ver ^¬ reinforcing elements, two frontally disposed Verstär ^¬ kung slices formed abrasive-free and dressable bar. The easily deformable Schleifbe ^¬ rich is edged and reinforced in this way from both ends.

It is further preferred that the material of the reinforcing discs has a transverse rupture strength of at least 15 MPa, preferably at least 20 MPa, more preferably at least 25 MPa. The Shore A hardness may be more than 100 before ^¬ . To measure the bending strength were quadratic

Test specimens measuring 16.2 mm x 16.2 mm x 120.4 mm were subjected to a 3-point bending test. The edition consisted of two metal rollers with a distance of the support points of 80 mm, the diameter of the metal rollers was 30 mm. During delivery, the crosshead speed was 10 mm / min. As a suitable, dressable material for the reinforcing ^¬ discs is basically a material based on a same or similar binder as for the

Grinding area used in question. This makes it easier to machine the grinding area and the reinforcing disks in one operation with the same tool. Suitable binders may be, for example, polyurethanes, phenol resins ^¬, glass or ceramic binder. Preferably, a filler may be provided for adjusting the desired mechanical properties and increasing the strength. They may be known mineral fillers, preferably hollow bodies based on minerals (microcoils). The filler according to the invention can ^¬ example, between 10 and 60 wt .-%, more preferably 20 to 40 wt .-% are. These upper and lower limits can be combined as desired to areas according to the invention.

It is preferred that the at least one reinforcing ^¬ disk surface is connected to the grinding area. Connected surface means that this reinforcing disk at least with a large surface area of more than 50%, preferably be ^¬ but full surface a frictional connection with the

Grinding area received, for example, is glued. This laminar bond prevents the grinding wheel from being compressed towards the central axis, resulting in a reduced dimensional stability in the grinding zone. Such a two-dimensional composite is not possible in the prior art in the ^¬ set steel discs, as they must be dismantled for dressing and then re-assembled. The material of the grinding region preferably has a ge ^¬ ringere hardness than the material of the reinforcement discs. Preferred is a range of Shore A hardness of 20 to 97, more preferred are ranges of 20-90 or 70-85, in the machining of hardened cylindrical metallic workpieces, for example, the hardness range of 70-85 may be useful. In a particularly preferred embodiment of the invention it is provided that the grinding area is annular and surrounds a hard core area. In this context, hard means that this core region has a greater hardness than the grinding region arranged radially outward therefrom. In the preferred circular

Grinding wheel, this core area, in particular the accelerating and centrifugal forces in the area of the bore on ^¬ take and derive. The core area thus has the opening or bore which serves to connect to the grinding machine. The core region may according to the invention consist of a same or similar material as the reinforcing discs.

In this preferred embodiment, a grinding wheel according to the invention thus consists of four structural ele ^¬ ments. It is the core area, the grinding area and two reinforcing discs. The core absorbs the described forces and driving forces in the area of the bore. In the context of the invention, it is also possible borrowed that the core region and the reinforcing discs are integrally formed or integrally connected to each other. Thus, it is also preferred that according to the invention the reinforcing disks extend over surface areas of the Grinding area and the core area extend and thus each area (or in the case of the core area in one piece) are connected. The combination of the reinforcing discs with both the grinding area and the core area makes it possible to carry out an effective force dissipation into the core area. A radial change in shape of the grinding area is thereby substantially prevented. Consequently, a significantly improved dimensional accuracy of the engagement zone of the grinding area is achieved against pressure forces during the grinding process. But it is also to be noted that even a strain is reduced interpreting ^¬ Lich by centrifugal forces when accelerating the grinding wheel to the desired Ar ^¬ beitsgeschwindigkeit. On the one hand, this allows the use of a binder which tends to be harder with a higher one

Grinding power. Because the grinding area is fixed flat to the reinforcing discs, the surface geometry of the grinding area tends to be maintained even under the pressure load of an application. Because of this better form fidelity is thus in a harder binder still the positive connection between the workpiece and engagement zone of the

Grinding area guaranteed. The inventive

On the other hand, grinding wheels also allow the use of particularly soft binders, as they may be required for the grinding of geometrically complicated workpieces. In this case, the grinding area can largely adapt to the workpiece contour and is stabilized by the reinforcing discs against deformation and cracking. Regardless of the binder chosen, generally higher working speeds can be achieved on ^{account of} the improved strength. This improves the efficiency of the grinding process, but can also allow the creation of special speed-dependent surface structures. According to the invention it is further preferred that the Wenig ^¬ least one reinforcement disc to extend over at least 80%, preferably at least 90% of the end face of arranged below the grinding area and / or the core region. This large-area design of the reinforcing discs allows effective stabilization and shape retention of the grinding area. The axial thickness of the at least one reinforcement disc, preferably, the common axial thickness of the two Verstär ^¬ kung discs, in a preferred embodiment 10-30%, more preferably 15-25% of the total thickness of the grinding wheel.

Another object of the invention is the use of a grinding wheel according to the invention for surface treatment. Preference is given to the surface processing of workpieces, preferably cylindrical workpieces and / or functional parts of machines. This is be ^¬ vorzugt not a large-scale processing planner FLAE ^¬ chen, but a relatively small-scale processing of curved surfaces such as cylindrical. Particularly preferred is the use for Oberflächenstruktu- ration. Surface structure means that no substantial change in shape of the surface in terms of a material removal is carried out more, but only a ge ^¬ desired surface structure is generated. Embodiments of the invention will be described below with reference to the single drawing showing a grinding wheel according to the invention in an axial and Radia ^¬ len view. Example 1 A grinding wheel according to the invention with the dimensions 300 mm (diameter) x 40 mm (width) x 76 mm (Bohrungsdurchmes ^¬ ser) consists of the structural elements of the grinding area with an abrasive layer and a core area in the region of the bore and two lateral reinforcement discs. These structural elements are initially called cylindrical

Produced blanks of great length and then cut by means of a Dia ^¬ manttrennscheibe such that accurately fitting, disc-shaped elements are obtained for further processing to the individual tool.

Prefabrication of the core area:

Recipe components: Rencast FC52 ISO (isocyanate based on MDI, Huntsman Ad ^¬ vanced Materials)

RENCAST FC52 poly (Formulated polyol, Huntsman ad vanced ^¬ material)

microspheres

SOPHERES SG-300 B (light filler, Omega Minerals Germany)

740 g of Rencast FC52 ISO, 740 g of Rencast FC52 poly and 762 g of ISOPHERES SG-300 B microspheres are mixed with a stirrer and mixed with a release agent

Aluminum mold with the dimensions 123 mm (diameter), 320 mm (length) and 70 mm (bore diameter) cast in. After a curing time of 30 minutes, the mass is formed and separated into two sections each with 155 mm.

These are referred to by means of turning on a messermaß Outer diameter of 120 mm is reduced and roughened in the subsequent Ar ^¬ beitsgang for better bonding.

Prefabrication of the grinding area:

Recipe ingredients:

RC-Dur 110 (diphenylmethanediisocyanate, Bayer MaterialScience)

Poly-G HQEE (crosslinker, hydroquinine di (beta-h) ester, CVH chemistry.)

Diorez 770/02 (polyester polyol, Azelis Switzerland Chemi ^¬ cals)

Dabco TMR 2 (activator, quartenary ammonium salt, Air

Products Chemicals)

Tegostab B 8905 (surfactant, CVH-Chemie-Vertrieb GmbH & Co.

Hannover KG)

Dipropylene glycol (solvent, CVH chemistry distribution)

Araldit AW 116 (epoxy resin, Fa. Epoxidharze Andreas Wegel)

Hardener HV 953 U Hardener to Alaldit AW 116, Fa. Epoxidharze

Andreas Weigel)

Byk-W 961 (structure improver, BYK chemistry)

SCG F 80 (abrasive grain silicon carbide green, grain size

F 80, ESK-SiC GmbH

Foamer (mixture of Tegostab 8905, Dipropy ^¬ glycol and water to each Weils same volume fractions)

Catalyst (mixture of dipropylene glycol (98.04

Ma.%) And Dabco TMR (1.96 Ma.%). Poly-G HQEE and Diorez 770/02 are mixed in a ratio of 4.76: 95.24 parts by mass and heated to 105 C 48 hours before Verwen ^¬ tion. The abrasive grain SCG F 80 is preheated in the same way.

The components RC Dur 110 (1079 g), frother (2 g), mixture Poly-G HQEE and Diorez 770/02 (3162 g), Byk-W 961 (5 g) and SCG F 80 (11859 g) become homogeneous mixed, time 60 s. After adding CAT1 (20 g), mix again (20 s).

In a preheated and coated with release agent Me ^¬ tallform with the dimensions 310 mm (diameter), 155 mm

(Width) and 70 mm (hole diameter), the prefabricated and with adhesive (Aaraldit) is underlined Kernbe plugged ^¬ rich. The exact central positioning he ^¬ follows it by means of a centering pin.

The mixture is poured in, the mold is sealed and heated in the oven to a temperature of 105 degrees to cure (20 minutes).

Finally, the mold is opened, the blank removed, clamped in a machining center and turned off the circumference to a dimension of 307 mm. In the same setting, a disk-shaped part of a width of 30 mm is finally cut off by means of a diamond cutting wheel.

Prefabrication of reinforcing discs:

The production of the reinforcing discs is made of the material that also used for the production of the core area has been. The description of the processing is to be applied correspondingly.

Recipe ingredients:

2498 g Rencast FC52 ISO

2498 g Rencast FC52 poly

2505 g microspheres ISOPHERES SG-300 B Dimensions of the mold:

310 mm (diameter)

120 mm (width)

70 mm (bore diameter) The diameter of the obtained cylindrical body is reduced in a machining center by turning to 307 mm. In the same clamping disc-shaped segments are cut by 5.2 mm width by means of a diamond cutting wheel.

Further processing:

Before further processing, the individual structural elements are checked. Criteria are dimensions, weight, density, hardness and breaking strength (support disks). Furthermore, a visual inspection for damage such as cracks, pores or inhomogeneities.

The reinforcing plates are stuck in succession on the core section, which are acted upon in each case during the Aushär ^¬ tezeit with pressure. Finally, the grinding wheel is machined by turning the faces, the bore and the circumference to the desired degree and the to obtain desired surface structure. Finally, by dressing the corresponding profile purpose corresponding circumferential profiling is generated. The final includes tests for dimensional accuracy and unbalance and a test run with the l, Ar ^¬ beitshöchstgeschwindigkeit 2-fold of 40 m / s.

To test the breaking strength, another test run was carried out. For this, a Arbeitshöchstge ^¬ speed of 40 m / s and in accordance with the tatsäch ^¬ handy application significantly increased safety factor of 3.5 has been based. Here, the safety factor is defi ^¬ ned as follows:

S _b r = (v _br / v _s ) ²

S _b r = safety factor against breakage due to centrifugal force

v _br = circumferential speed at break by centrifugal force V _s = operating speed corresponding permissible peripheral speed of a rotating grinding tool ^¬

It follows that for a working speed of 40 m / s, assuming a safety factor of 3.5, the minimum break peripheral speed is 75 m / s.

During the test run was a peripheral speed of Ver ^¬ searchpattern of 75 m / s can be achieved without causing mechanical breakdown or visible damage.

The grinding wheel according to the invention is shown schematically in the figure. Reference number 1 shows the core area, which may be interspersed in whole or in part by a bore for clamping on a grinding machine. The reference numeral 2 indicates the grinding area. It can be seen that this is concavely curved on the circumference in order to be able to grind cylindrical workpieces there. The reinforcing discs have the reference numeral 3.

After prolonged use of the grinding wheel may be required from a judge. Since the reinforcing discs 3 are made of dressable material, they can easily be dressed together with the grinding area 2.

Example 2:

Tool :

Grinding wheel according to Example 1, but with the deviating ^¬ the dimensions 200 x 30 x 76.2 mm (outer diameter x width x bore diameter).

Grinding machine:

Special machine of Fa. Thielenhaus workpiece:

Cylinder made of 100Cr6, diameter 26 mm, length 1200 mm

Pre-processed by grinding with a bonded grinding wheel of grain F80.

Rz = 2.0 - 3.0 ym

Oversize <0.01 mm

The grinding wheel we first with a Einkorndiamanten CNC-controlled with a degree of coverage Ud> 4 concave pro ^¬ filiert.

Grinding wheel and workpiece are arranged to each other so that the spindle of the grinding machine behaves ^¬ right angle to the longitudinal axis of the workpiece. Entspre ^¬ accordingly moves the grinding wheel during the machining of the cylindrical workpiece in the axial direction thereof as each double stroke.

After a processing step in each case a Rota ^¬ tion of the workpiece is carried out by 30 degrees.

The following application parameters apply to the grinding:

Working speed: 35 m / s

Feed rate in axial direction: 10 m / min contact pressure of grinding wheel 4-6 bar After machining, the workpiece has a uniform, axially extending surface structure with a mean roughness Ra <0.4 ym.

Claims

claims

Grinding wheel, with a circumferentially acting grinding area (2), the bonded abrasive on ^¬ has; and not participating in the auditory canal grinding reinforcing elements (3), characterized in that the reinforcement elements of at least a front side ^¬ arranged reinforcement disc (3) have formed abrasive free and be dressed.

Grinding wheel according to claim 1, characterized in that the reinforcing elements have two frontally arranged reinforcing discs (3), which are formed without abrasion and dressable.

Grinding wheel according to claim 1 or 2, characterized in that the material of the reinforcing discs (3) has a bending strength of at least 15 MPa, preferably at least 20 MPa, more preferably at least 25 MPa.

Grinding wheel according to one of claims 1 to 3, characterized in that the at least one Ver ^¬ reinforcing disc (3) is connected flat with the grinding area (2).

Grinding wheel according to one of claims 1 to 4, characterized in that the at least one Ver ^¬ reinforcement disc (3) comprising a binder and / or filler materials ^¬.

6. grinding wheel according to a 5, characterized in that the filler content of the reinforcing discs (3) 10 to 60 wt .-%, preferably 20 to 40 wt .-% be ^¬ contributes.

Grinding wheel according to one of claims 1 to 6, characterized in that the material of the grinding ^¬ area (2) has a Shore A hardness of 20 to 97 ^¬ .

Grinding wheel according to one of claims 1 to 7, characterized in that the grinding region (2) is annular and surrounds a hard Kernbe ^¬ rich (1).

Grinding wheel according to claim 8, characterized in that the at least one reinforcing plate (3) over surface portions of the grinding area (2) and of the core region (1) and thus each sur fa ^¬ chig connected.

10. Grinding wheel according to one of claims 1 to 9,

characterized in that the at least one Ver ^¬ reinforcing plate (3) over at least 80 ~ 6, preferably extends in front of at least 90% of the end face of arranged below the grinding area (2) and / or core region (1).

11. Grinding wheel according to one of claims 1 to 10,

characterized in that the axial thickness of the we ^¬ least one reinforcing disc (3) is 10 to 30%, preferably 15 to 25% of the total thickness of the grinding ^¬ slice.

12. Use of a grinding wheel according to one of claims 1 to 11 for surface treatment.

13. Use according to claim 12 for the surface treatment of workpieces, preferably cylindrical workpieces and / or functional parts of machines.

14. Use according to claim 12 or 13 for surface structuring.