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Title:
SURFACE PROTECTION STRUCTURE OF DIAMOND FOR SURFACES OF SECURITY DEVICES, IN PARTICULAR PROVIDED IN DOORS OF SAFES OR IN LOCKS OF ARMOURED DOORS
Document Type and Number:
WIPO Patent Application WO/2019/049092
Kind Code:
A1
Abstract:
There is described a surface protection structure of diamond for surfaces of security devices, in particular provided in doors of safes or in locks of armoured doors, comprising a layer of reduced thickness which is formed by powders of diamond grains which are enclosed in a binder material and which is provided to be applied to the surfaces, diamond grains having a grain size dimension between 20 mesh (850 μm) and 120 mesh (125 μm) being distributed in the layer with a surface density having a value between 0.025 and 1 carat/cm2, and the binder material having in the layer a surface density having a value between 0.01 and 0.4 grammes/cm2, with such a coverage level of the diamond grains that the depth of the binder material measured over the thickness of the layer has a value between 50% and 100% of the nominal dimension of diamond grain.

Inventors:
GONZO FERRUCCIO (IT)
ZANDONELLA NECCA DINO (IT)
CARLET ENNIO (IT)
Application Number:
PCT/IB2018/056877
Publication Date:
March 14, 2019
Filing Date:
September 10, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
ADI S R L (IT)
International Classes:
B23K35/30; B23K35/32; B24D3/06; B24D3/08; B24D18/00; C22C1/05; C23C28/00; C23C28/02; C23C28/04; C23C30/00
Foreign References:
US4018576A1977-04-19
GB1462510A1977-01-26
US20130267154A12013-10-10
US20030087097A12003-05-08
US4798026A1989-01-17
US4859541A1989-08-22
Attorney, Agent or Firm:
FABRIS, Stefano et al. (IT)
Download PDF:
Claims:
CLAIMS

1. A surface protection structure of diamond for surfaces of security devices, in particular provided in doors of safes or in locks of armoured doors, characterized in that it comprises a layer of reduced thickness which is formed by powders of diamond grains which are enclosed in a binder material and which is provided to be applied to the surfaces, in that diamond grains having a grain size dimension between 20 mesh (850 μιη) and 120 mesh (125 μιη) are distributed in the layer with a surface density having a value between 0.025 and 1 carat/cm2, and in that the binder material has in the layer a surface density having a value between 0.01 and 0.4 grammes/cm2, with such a coverage level of the diamond grains that the depth of the binder material measured over the thickness of the layer has a value between 50% and 100% of the nominal dimension of diamond grain.

2. A protection structure according to claim 1, wherein the layer is substantially a single layer, the thickness of which is equal to the greatest dimension of the diamond grain between the dimensions of the grains enclosed in the layer.

3. A protection structure according to claim 1 or 2, wherein the binder material which encloses the diamond is a brazing metal alloy.

4. A protection structure according to claim 3, wherein the brazing alloy is of the type containing elements similar to carbon.

5. A protection structure according to claim 1 or 2, wherein the binder material is a metal material applied by electrolytic deposition.

6. A protection structure according to claim 5, wherein the metal binder comprises Ni or Ni-P alloys.

7. A protection structure according to one or more of the preceding claims, wherein the minimum dimension of diamond grain used in the layer is greater than from 50 to 60 mesh (300-250 μιη), and preferably greater than from 40 to 50 mesh (425- 300 μιτι).

8. A protection structure according to any one of claims 1 to 7, wherein, in the layer, a percentage which is no greater than 30% by weight of the diamond enclosed in the layer is formed by a fine grain having a grain size dimension of from 60 to 120 mesh (250-125 μιη), the remaining percentage by weight being formed by grains having greater grain size dimensions.

9. A protection structure according to claim 8, wherein a percentage which is no greater than 30% by weight of the diamond enclosed in the layer is formed by grains having a grain size dimension of from 100 to 120 mesh (150-125 μιτι), the remaining percentage by weight being formed by grains having a grain size dimension of from 30 to 40 mesh (600-425 μιη) or from 20 to 30 mesh (850-600

Mm).

Description:
Surface protection structure of diamond for surfaces of security devices, in particular provided in doors of safes or in locks of armoured doors

Technical field

The present invention relates to a surface protection structure of diamond for surfaces of security devices, in particular provided in doors of safes or in locks of armoured doors.

Technological background

In the technical sector being referred to of security devices, and in particular in the field of safes and armoured doors, there is known the need for maximizing the resistance to breaking and entering of the structural elements used in such devices. This requirement typically becomes evident in the use of suitable materials, for example, steel, which may be used in a multiple-layered structure, for constructing plates which form or which are inserted in the walls or in the doors of safes or in armoured doors or which are provided for the protection of the locks of such doors. Normally there must be ensured in these structures an adequate resistance to cutting and/or perforation, increasing the time required for consuming the material subjected to cutting or perforation by the equipment involved in the breaking and entering.

The use of steel plates, including with a multi-layered structure, and optionally using alloyed steels (for example, steel with manganese), allows a good resistance to the action of drilling but does not generally afford suitable resistance to cutting, for example, by a grinding wheel with an abrasive cutting disk.

In the different technical field of mechanical processing operations, in particular those which use abrasive tools, it is known to use diamond inside the used materials in order to produce the operating surfaces of the tool having a particular hardness and resistance to wear.

Description of the invention

In the context of the present invention, a main object of the invention is to provide a surface protection structure of diamond which is structurally and functionally configured to overcome the limitations set out with reference to the cited prior art, which is particularly suitable for producing a selective protection in doors of safes or in protection plates of locks for armoured doors.

This object and other objects which will be set out clearly below are achieved by the invention by means of a surface protection structure of diamond for surfaces of security devices which is produced according to the appended claims.

Brief description of the drawings

Other features and advantages of the invention will be better appreciated from the following detailed description of a preferred embodiment thereof which is illustrated by way of non-limiting example with reference to the appended drawings, in which : - Figure 1 is a schematic cross-section of a surface protection structure of diamond which is produced according to the invention,

- Figure 2 is a schematic cross-section of a second example of a surface protection structure of diamond according to the invention,

- Figure 3 is a schematic cross-section of a third example of a surface protection structure of diamond of the invention,

- Figure 4 is a schematic view of an example of a plate-like element which is provided with a selective surface protection which is produced with the protection structure of diamond of the invention,

- Figure 5 is a view corresponding to that of Figure 4 of another example of a plate- like element which is provided with a different configuration of the protection produced by the protection structure of diamond of the invention,

Preferred embodiments of the invention

With reference to the Figures cited, there is generally designated 1 a surface protection structure of diamond of a plate-like structure 2, which surface protection structure is schematically illustrated as a cross-section and is intended for the production of security devices. The element 2 is suitable for producing, for example, plates or sheets of sheet metal, for example, of steel, which is intended to be used in the structures of the panels of doors for safes or in the lock protections of armoured doors, in both cases with an anti-theft function.

The plate-like geometry of the element 2 to which the protection structure 1 is applied is a typical geometry which may be encountered in security devices, but it is not intended to be considered to be limiting, the invention in fact also being used in the presence of surface geometries which are neither strictly plate-like nor have planar surface profiles. Surfaces of hinges of security frames and security padlocks, which are distinguished by surface profiles which are not typically planar, may in fact, for example, be the area of use of the invention.

The structure 1 comprises a layer la of reduced thickness which is formed by powders of diamond grains 3 which are enclosed in a binder material 4, in particular a metal binder, and which is provided to be applied to a surface 2a of the plate-like element 2. The diamond is advantageously an industrial diamond, of a synthetic nature. The invention would thus be used, if it should be used, as an abrasive material, cubic boron nitride (abbreviated to CBN).

In the Figures, the grains 3 of diamond are schematically illustrated in a simplified manner by the spherical shape (circular in the cross-sectional view of Figures 1 to 3). The grains 3 of diamond have, according to the invention, a grain size dimension between 20 mesh (850 μιη) and 120 mesh (125 μιη) and are distributed in the layer la with a surface density having a value between 0.025 and 1 carat/cm 2 .

With regard to the grain size, reference is made to the unit of measurement "mesh" (US sieve mesh) and there is set out below a table of correlation with the international designation FEPA, wherein the number which follows the letter "D" indicates the nominal grain size dimension expressed in micrometres:

D852 (20-30 mesh)

D602 (30-40 mesh)

D427 (40-50 mesh)

D301 (50-60 mesh)

D251 (60-70 mesh)

D252 (60-80 mesh)

D213 (70-80 mesh)

D181 (80-100 mesh)

D151 (100-120 mesh)

Tests carried out by the Applicant have shown that the grains of diamond which can be used with greatest efficacy in the application of the invention are those between D852 (20-30 mesh) and D151 (100-120 mesh), with each of the ranges indicated above and/or combinations thereof.

For the application of the invention, "large grains" are conventionally considered to be those with dimensions greater than or equal to D301 (50-60 mesh), that is to say, from D852 to D301, and "fine grains" are considered to be those with a dimension less than D301, that is to say, from D151 to D251.

It will be understood that any combination of grain which is effective in the application of the invention thus comprises a percentage of one or more large grain(s) optionally supported by fine grains.

With regard to the concentration or density of the diamond, reference is advantageously made to a concentration or density for units of surface-area, given that the layer la is constructed with reduced thickness, and in particular can be assimilated in a single layer, the thickness dimension S of which is substantially equal to the nominal value of the largest dimension of grain among those used in the formation of the layer.

The concentration is indicated below in carats per cm 2 (crt/cm 2 ), it being understood that the carat as a unit of measurement of weight for the diamond corresponds to 0.2 gramme.

The concentration values (or surface density) defined for the applications of the invention with reference to some classes of grain size are as follows:

D852 (20-30 mesh) : 0.4-1 crt/cm 2

D602 (30-40 mesh) : 0.3-0.7 crt/cm 2

D427 (40-50 mesh) : 0.2-0.5 crt/cm 2

D301 (50-60 mesh) : 0.1-0.4 crt/cm 2

D181 (80-100 mesh) : 0.05-0.2 crt/cm 2

D151 (100-120 mesh) : 0.025-0.18 crt/cm 2

With regard to the binder material which encloses the grains of diamond, there are indicated below some values which are defined for the application of the invention and which refer to some classes of grain size, in which the quantity of material is expressed by weight for units of surface-area (with units of measurement: gramme per cm 2 - g/ cm 2 ) :

D852 : 0.1 - 0.4 g/cm 2 D602: 0.1 - 0.25 g/cm 2

D427: 0.1 - 0.20 g/cm 2

D301 : 0.05 - 0.125 g/cm 2

D181 : 0.025 - 0.09 g/cm 2

D151 : 0.01 - 0.07 g/cm 2

There is provision according to the invention for the binder material 4 to have in the layer la a surface density having a value between 0.01 and 0.4 gramme/cm 2 , with such a coverage level of the diamond grains that the depth H of the binder material measured over the thickness S of the layer has a value between 50% and 100% of the nominal dimension D of the diamond grain having a grain dimension which is greatest among those used.

The relationship between the depth H of binder, thickness S of the layer and nominal dimension D of the grain is clearly shown in Figure 1, wherein there is illustrated a single-layered structure which is produced by a combination of large grains and fine grains, in which the depth H of the binder measured over the thickness S is slightly less than 100% of the nominal dimension D of the grain having the greatest dimension present in the layer la.

In the example of the protection layer of Figure 1, the thickness S is therefore equal to the greatest dimension of a diamond grain among the dimensions of the grains enclosed in the layer.

It can be seen that, unlike the production of diamond-containing equipment in which the depth of the binder in relation to the nominal dimension of grain of the diamond is always far less than 50%, the diamond having to be well exposed in order to perform the function of cutting thereof, in the application of the present invention the diamond which remains well enclosed inside the binder material in order to prevent it from being exposed by the protection layer during the attempt at breaking and entering, under the action of the cutting or perforation tool, is advantageous.

With regard to the application of the binder material, in an embodiment of the invention there is provision for the binder (which encloses the diamond) to be a brazing metal alloy, and advantageously to be a brazing alloy of the type comprising elements similar to carbon (by which the diamond is constituted), selected, for example, from the following : Cr, Si, W, Ti, Ta, Nb.

By way of example, a typical composition may contain (with residual parts of nickel) : Cr (6-25%), Si (0-10%), P (0-11%), Fe (0-5%), B (0-4%), W (from 0 to 10%), Ti (from 0 to 10%), Ta (from 0 to 10%), Nb (from 0 to 10%), C (0-1%). Typical brazing temperatures of such brazing alloys are between 800 and 1100°C. In another embodiment, the binder material is a metal material applied by electrolytic deposition and wherein preferably the metal binder comprises Ni or Ni-P alloys.

It should be noted that, with grains of diamond used from D852 (20-30 mesh, 850- 600 μιη) to D151 (100-120 mesh, 150-125 μιη) or combinations thereof, unlike what occurs in the field of the electrolytic equipment, there can be used baths with mixed diamond (large grains mixed with fine grains). The deposition time (nickel coverage) will be increased with respect to the one of a tool. However, in order to advantageously limit the diamond-coating time, it is possible to use much greater currents with respect to those typically used in the electrolytic diamond-coated tools where excesses of coverage, resulting from high currents, are considered to be a defect, while there are advantages in the application of the invention where the diamond has to remain well enclosed. With reference to the configuration of the protective layer of Figure 2, if it is intended to prioritize the resistance to cutting (with respect to the resistance to drilling), it has been found to be preferable to use a single large grain at a high concentration (high portion of the concentration ranges with reference to the grain). Generally, the greater the dimension is of the particles of diamond used, the greater is the resistance to breaking and entering by means of an abrasive cutting disk.

The minimum grain which can be used is D301 and for a firm resistance it is advantageous to exceed D427.

It has further been found that the better resistance to drilling is obtained by using a mixture of large grain and fine grain (Figure 1), the latter at a maximum percentage by weight of 30%. A preferred example may provide for 70% by weight to be formed by grains with a grain size D602 (30-40 mesh, 600-425 μιτι) or D852 (20-30 mesh, 850-600 μιτι) and the remaining 30% by weight to be formed by grains with a grain size D151 (100-120 mesh, 150-125 μιη).

The resistance to drilling is generally highly dependent on the hardness and the thickness of the fixing alloy and, to a lesser extent, on the grain and concentration of the diamond used. However, the resistance to cutting with an abrasive cutting disk improves with the increase of grain and concentration of the diamond used, while it is only slightly dependent on the type of fixing alloy of the diamond.

In an embodiment, there is provision in the protection structure for the minimum dimension of diamond grain used in the layer to be greater than from 50 to 60 mesh (300-250 μιη), and preferably greater than from 40 to 50 mesh (425-300 Mm).

In another embodiment, there is provision for a percentage which is no greater than 30% by weight of the diamond enclosed in the layer to be formed by a fine grain having a grain size dimension of from 60 to 120 mesh (250-125 μιη), the remaining percentage by weight being formed by grains having greater grain size dimensions.

In another embodiment, there is provision for a percentage which is no greater than 30% by weight of the diamond enclosed in the layer to be formed by grains having a grain size dimension of from 100 to 120 mesh (150-125 μιη), the remaining percentage by weight being formed by grains having a grain size dimension of from 30 to 40 mesh (600-425 μιη) or from 20 to 30 mesh (850-600 μηη).

Figure 3 relates to another embodiment of the invention, in which the protection structure is obtained with planar sintered elements or inserts 4' which are provided in order to be fixed to the surface 2a by means of soldering/brazing or adhesive bonding or mechanical fixing. The soldering/brazing material or adhesive material, if present, is designated 5.

Those sintered elements preferably comprise diamond grains having different grain sizes from D852 (20-30 mesh, 850-600 μιη) to D151 (100-120 mesh, 150-125 μιη), or combinations thereof, which are enclosed in a sintered metal alloy, which is advantageously obtained from powders containing one or more of the following elements: Fe, Co, Ni, Cu, Sn, Zn, Mo, Mn, W. These elements are at suitable proportions and so as to ensure the desired mechanical properties, the retention of the diamond and the ability to be brazed or bonded to steel supports.

Typical temperatures of the sintering process are between 500°C and 1000°C.

Preferred volumetric concentrations of the diamond are between C50 and C200, corresponding, in the binder/diamond compound, to volumetric concentrations of diamond from 12.5% to 50% by volume. The concentrations C50 and C200 are expressed on the measurement scale according to which CIOO corresponds to a concentration of 4.4 carats/cm 3 . Therefore, C50 is equivalent to a concentration of 2.2 carats/ cm 3 and C200 is equivalent to a concentration of 8.8 carats/ cm 3 .

All the above-mentioned embodiments, either with a brazing alloy or electro- deposited or sintered binder, further allow according to the invention a selective deposition on areas which are greatly exposed to breaking and entering (with a consequent reduction of the material costs).

Figures 4 and 5 show, merely by way of example, two different configurations of the areas with diamond-coated protections which are applied to the surface 2a of a plate-like element 2. In Figure 4, the plate is provided with 5 different protection structures or elements which are positioned selectively so as to safeguard respective areas, all designated A. In Figure 5, the areas protected are further subdivided into sub-areas, which are all designated B and which allow a further reduction of the material costs.

The protections can be produced in the specific areas, of any shape, equally well with a single layer with fixing of the diamond by means of direct brazing, single layer with electrolytic deposition or with sintered elements which contain a diamond dispersion.

The sintered elements are produced according to a substantially two-dimensional geometry with shapes corresponding to the area to be protected and a uniform thickness, preferably between 1 and 4 mm.

The sintered material may contain diamonds having a single grain or mixtures of grains, according to the indications already set out for the single-layered protections. Other non-limiting examples of geometries of the areas of deposition may be: stripes, zig-zags, spirals.

In the single-layered diamond-coating for brazing or with sintered elements which have a geometry which is substantially two-dimensional and which are fixed with a soldering/brazing process, a selective and therefore discontinuous deposition further reduces the problem of withdrawal of the brazing alloy during the step of solidification with a resultant reduction of the thermal deformations especially in the case of two-dimensional extended supports (sheets or plates).

The diamond-coated areas can therefore be covered with different grains and concentrations of diamond. The quantities of fixing alloy of the diamond can still be differentiated by quantity per unit of surface-area.

The diamond coating can be carried out in the various zones with diamond of large grains, fine grains or with mixed grains so as to maximize the volumetric content of diamond in the deposited layer.

The quantity of fixing alloy is substantially greater than that used for the production of brazed or electro-deposited equipment, wherein the diamond in order to perform its function has to be exposed, or to protrude from the alloy itself. In the protections according to the invention, the diamond has to remain preferably well embedded in the alloy so as not to be readily exposed and to perform to the maximum level its own function of combatting the equipment for breaking and entering used (abrasive tip or disk for cutting).

The invention thereby achieves the objects set out by achieving the advantages set out with respect to the cited prior art.