WO2020126460A1

WO2020126460A1 - Device and method for lapping workpieces

Info

Publication number: WO2020126460A1
Application number: PCT/EP2019/083429
Authority: WO
Inventors: Herman RAVELOJAONA; Nicolas Gautreau
Original assignee: IFP Energies Nouvelles
Priority date: 2018-12-18
Filing date: 2019-12-03
Publication date: 2020-06-25
Also published as: FR3089837A1; FR3089837B1

Abstract

The present invention relates to a device for supporting workpieces to be lapped (1) adapted to the lapping ring (5) of a lapping machine. The device comprises an outer casing (10), arranged on the lapping ring (5) and comprising at least one drilled passage (40). This outer casing (10) is configured to contain at least one workpiece to be lapped (1). In addition, the device comprises a rod (50) ending in a pointed end (60), the axis of the rod (50) being substantially vertical. The rod (50) passes through the outer casing (10) via the drilled passage (40) which is useful as a guide for same and the pointed end (60) of the rod (50) is intended for being positioned in a recess (E) of the workpiece to be lapped (1). A weight (30) is positioned on the rod (50). The invention also relates to a lapping machine provided with such a support device and a lapping method that uses this type of lapping machine with support. The systems and methods according to the invention allow better lapping quality and complete automation, without the need for manual reworking.

Description

DEVICE AND METHOD FOR LAPPING WORKPIECES

Technical area

The present invention relates to the field of lapping materials and more particularly to lapping with a view to observing the composition and / or structure of porous materials such as rocks or polymeric materials. Applications of these observations relate in particular to the field of geosciences.

The observation of these materials is generally carried out under a microscope. The samples observed are blades known as “thin blades” of three types: blades of very thin materials on the order of 30 μm, thicker blades on the order of 100 μm or polished sections whose thickness can go up to '' at 10 mm. In order to correctly observe these different types of samples under the microscope, it is necessary to have a flat surface and a very low roughness (almost smooth).

The running-in stage of these samples therefore plays an essential role with a view to their subsequent observation under the microscope.

Prior art

Usually, the running-in operations are carried out:

Either manually and individually (sample by sample)

- Either automatically on a prowler.

When these operations are performed manually, they are done individually, sample by sample, using abrasives on a glass plate. First, the lapping operator uses abrasives with large particle sizes, then it gradually decreases the particle size of the abrasive. The smaller the grain size of the abrasive, the lower the roughness of the lapping part (sample for example) and therefore the smoother the lapping part. During lapping, the operator applies manual force to the part to be lapped to press it against the abrasive and the glass plate, while describing a relative movement in the form of an “eight” of the part with respect to to the assembly consisting of the abrasive and the glass plate. Figure 1 illustrates, in top view, the movement 2, in "eight", followed by the workpiece 1 and induced by the operator, on the glass plate 3 'covered with an abrasive. Unfortunately, the force exerted and the shape of the movement are irregular, taking into account manual actions. The result is often insufficient and requires re-lapping, causing additional time to run in with a surface of sufficient quality for observation under the microscope. In addition, the gesture being repetitive for the operator, these operations can be sources of tendonitis for him. FIG. 2 illustrates the principle of conventional lapping from a prowler, such as an LM300 ™ prowler (sold by the company ESCIL). FIG. 2 is a top view of the prowler. A lapping plate 3, covered for example with a film of water, is rotated according to a movement M. On this lapping plate 3, several pieces to be lapped 1 are placed. These lapping parts 1 are placed in a lapping ring 5 which surrounds them. The lapping ring 5 is held in an articulated arm which can perform rotational movements around the vertical axis of rotation A. The movement of the lapping ring 5 is due to the rotation of the lapping plate 3 and optionally to the oscillation of the articulated arm 4. These movements cause the lapping parts 1 to rotate m2 in the lapping ring 5. The relative movements of the lapping parts 1 and the lapping plate 3 allow the lapping of the lapping parts 1 , by friction.

FIG. 3 illustrates, diagrammatically and in side view in section, the conventional mounting of the lapping parts 1 in the lapping ring 5. Several lapping parts 1 are positioned in the lapping ring 5, the lapping face of the part to be lapped being in contact with the lapping plate 3, the surface of which is abrasive. Above the lapping parts 1, a foam 8 is placed on which a mass 9 is placed. The foam 8 serves to hold the lapping parts 1 together and the mass 9 serves to press and hold the lapping parts 1 against the abrasive of the lapping plate 3. However, the system constituted by the foam 8 and the mass 9 is fragile and unstable and the parts to be lapped 1 tend to overlap during lapping operations, making operations more complex, even making them impossible. Furthermore, when the lapping parts 1 do not overlap, the weight applied by the mass 9 is not suitable for all the different lapping parts 1 or is poorly distributed: it follows that the desired roughness is not obtained and the parts to be lapped are, most often, taken up manually one by one until a lapping finish compatible with observation under the microscope. The flatness and roughness obtained are checked after running in using a rule, known to a person skilled in the art. These manual operations are also synonymous with additional time to reach the necessary final break-in.

To overcome the aforementioned drawbacks, the invention relates to a support device for lapping parts suitable for the lapping ring of a prowler. The device comprises an outer casing, disposed on the lapping ring and comprising at least one drilled passage. This outer casing is configured to contain at least one part to be lapped. In addition, the device comprises a rod ending in a pointed end, the axis of the rod being substantially vertical. The rod passes through the outer casing through the drilled passage which serves as a guide and the pointed end of the rod is intended to be positioned in an imprint of the part to be lapped. A mass is positioned on the rod. The invention also relates to a prowler equipped with a device as defined above. The prowler comprises a lapping plate with a lapping surface, a lapping ring and an articulated arm which drive the lapping ring. The support device is positioned so that the lapping face of the part to be lapped is positioned against the lapping plate and the outer casing is placed on the lapping ring.

Furthermore, the invention also relates to a method of lapping at least one part to be lapped, using a prowler as defined above, for which:

- the part to be lapped is positioned on the lapping plate;

- the outer casing is positioned around the part to be lapped, the outer casing being positioned above the lapping ring;

- The rod is positioned with the associated mass so that the pointed end of the rod is in contact with the part to be lapped, the rod being guided by the passage drilled in the outer casing;

- the outer envelope is made to describe movements on the lapping plate, by rotation of the plate and optionally by oscillation of an articulated arm.

Summary of the invention

The invention relates to a support device for lapping parts for a prowler, said device comprising a lapping ring, an external casing, said external casing being disposed on said lapping ring, said external casing comprising at least one drilled passage, said casing being configured to contain at least one part to be lapped. In addition, the device comprises a rod ending in a pointed end, the axis of said rod being substantially vertical, said rod passing through said outer casing by said pierced passage, the pointed end of said rod being positioned on said work-in and a mass being positioned on said rod.

Advantageously, said external casing is configured to contain several parts to be lapped, preferably between 4 and 10 parts to be lapped, and said device comprises several rods, each of said rods passing through a different drilled passage in said external envelope.

According to one embodiment of the invention, said mass is positioned outside of said external envelope.

According to a variant of the invention, said mass is positioned in said external envelope.

According to one embodiment of the invention, said external envelope has a cylindrical shape closed by a cover, said pierced passage being produced in said cover. According to a variant, said running-in ring and said external casing are produced by the same single piece.

The invention also relates to a prowler comprising a lapping plate with a lapping surface, an articulated arm driving the support device according to one of the preceding characteristics, for which the support device is positioned so that said face to be lapped of said lapping part is positioned against the lapping plate.

The invention also relates to a lapping method of at least one part to be lapped using a prowler according to the preceding characteristic for which:

- Positioning said part to be lapped on said lapping plate;

- Positioning said outer casing around said lapping part, said outer casing being positioned above said lapping ring;

- Positioning said rod with said associated mass so that said pointed end of said rod is in contact with said workpiece, said rod being guided by said passage drilled in said outer casing;

- The said external envelope is made to describe movements on the said lapping plate, by means of the said articulated arm, the said lapping plate itself being in motion.

Preferably, said mass positioned on said rod is adapted to the material of said part to be lapped and to the expected finish of said lapping.

Advantageously, several pieces to be lapped are positioned on said lapping plate, for which each part to be lapped is engaged with a different rod.

According to a variant of the invention, a separate mass is positioned on each of the rods. According to another variant of the invention, a common mass is positioned for all the rods.

Preferably, the method comprises a prior step of producing an impression in said part to be lapped, said rod being positioned in said impression.

Advantageously, said imprint is a notch with a depth of between 1 and 3 mm.

List of Figures

[Fig 1]

Figure 1 shows the principle of manual lapping of the prior art.

[Fig 2]

FIG. 2 represents the principle of automatic running-in by a prowler of the prior art.

[Fig 3]

FIG. 3 represents the mounting of the parts to be lapped in the lapping ring of a prowler of the prior art.

[Fig 4] Figure 4 shows, schematically and without limitation, an embodiment of the support device according to the invention.

Description of the embodiments

The invention relates to a support device for lapping parts for a prowler. The device comprises a lapping ring, an external casing, arranged on the lapping ring. The outer casing is integral with the ring, for example fixed by clamping on the lapping ring. It may or may not be fixed to the lapping ring. The outer shell includes at least one pierced passage. This outer casing is configured to contain at least one part to be lapped. In addition, the device comprises a rod ending in a pointed end, the axis of the rod being substantially vertical. The rod passes through the outer casing through the drilled passage which serves as a guide and the pointed end of the rod is intended to be positioned on the part to be lapped, preferably in an impression made on the part to be lapped: in this way , the imprint prevents any relative translation, in the horizontal plane, of the rod relative to the part to be lapped. A mass is positioned on the rod: thus, the part to be lapped is maintained with a constant force, which allows a better finish of lapping. In addition, as the rod is guided by the drilled passage, it maintains a substantially vertical position, which limits the movements of the part to be lapped relative to the external casing and therefore further improves the quality of the lapping thus produced.

The device according to the invention has the advantage of being able to be adapted to all existing prowlers.

In one aspect, the outer shell may have substantially the shape of a cylinder closed by a cover, the cover being substantially horizontal. For this embodiment, the drilled passage can be made in the cover, in order to ensure the vertical direction of the rod.

Alternatively, the cover can have other shapes, such as a domed shape for example.

According to a variant of the invention, the running-in ring and the external envelope can be produced by the same single piece. Thus, the assembly is simplified.

Preferably, the external envelope can be configured to contain several parts to be lapped. Preferably, the outer casing can be configured to contain between four and ten parts to be lapped. This configuration is particularly advantageous because it allows simultaneous and automatic lapping of several parts to be lapped, which saves time. In the case where the outer casing contains several parts to be lapped, the device then comprises several rods, each of these rods then passing through a different drilled passage in the external casing and each of these rods then comprises its own mass. In addition, each rod is supported on a separate lapping part. The mass put in place on each of the rods can then be adapted to the material to be lapped and to the expected lapping finish: according to a first example, to improve the lapping finish for the same material, the mass can be increased. In a second example, to obtain the same lapping finish with a harder material compared to a softer material (the terms “hard” and “soft” being relative between the two materials considered), the mass can be increased. The mass can also be adapted to other parameters such as the speed of rotation, the running-in time. Thus, the force which keeps the part to be lapped in abutment on the lapping surface is constant for each of the parts to be lapped. In addition, each of the rods being substantially vertical thanks to the guidance induced by the drilled passage and the pointed end of each of the rods being positioned in an imprint of each of the parts to be lapped, this mounting prevents the superimposition of the parts to be lapped one on the other. the others during the running-in operations.

This configuration is also advantageous because the independence of each of the assemblies constituted by a mass, a rod and a lapping part allows lapping of lapping parts which may have different sizes, the adaptation of the rods and masses allowing ensure a good lapping finish simultaneously with all the parts to be lapped.

According to an embodiment of the invention, the mass can be positioned outside the outer envelope. Therefore, the mounting of the rod through the outer casing is simplified and the size of the outer casing is not necessarily dimensioned to contain the mass.

According to another embodiment of the invention, the mass can be positioned in the external envelope. In this configuration, the mass is located between the point of support on the workpiece and the guide formed by the drilled passage. This positioning tends to bring the rod naturally in the vertical direction.

FIG. 4 illustrates, schematically and without limitation, an embodiment of the support device according to the invention. Indeed, lapping parts 1 are arranged on a lapping plate 3. The lapping faces of lapping parts 1 are in contact with the lapping plate 3, covered with an abrasive. Parts to be ground in 1 are positioned in a ring break-in 5 of a prowler. The lapping ring 5 is held in an articulated arm 4, for example by means of rollers 12. The rollers 12 allow rotation of the lapping ring 5, in the articulated arm 4. The articulated arm 4 can keep a position fixed or oscillate on the lapping plate 3 around the axis of rotation A, by means of oscillation. The rotation of the lapping plate 3 causes that of the lapping ring 5 in the articulated arm 4. The articulated arm 4 comes to tighten the lapping ring 5 by means of the rollers 12 allowing rotation of the lapping ring in the articulated arm 4. This movement and that of the lapping plate cause the lapping of the parts to be lapped 1 which are positioned in the outer casing 10. The articulated arm is driven in rotational movement around an axis by means of rotation which may include a motor, possibly associated with a transmission means and possibly a control means.

The rotation of the lapping plate 3 and, optionally the movement of the articulated arm 4, allow the lapping ring 5 to rotate inside the articulated arm 4. An external casing 10, constituted for example by a vertical wall 15 and a cover 20 rigidly fixed together and preferably in one piece, is disposed on the lapping ring 5. For example, the vertical wall 15 may be a cylindrical wall which adapts to the lapping ring 5 so that it can be deposited or fixed on the lapping ring 5. The cover 20 can be a substantially horizontal flat plate. The cover 20 has pierced passages 40, preferably the drilling axis of the pierced passages 40 is vertical, whatever the shape of the cover 20. Rods 50 can pass through each of these pierced passages 40. The lower end of each of the rods preferably has a pointed shape 60, so as to be able to be inserted into an imprint E, such as a notch, which has been produced in the workpiece to be ground in 1, the imprint E serving for housing the pointed end 60 of the rod 50, the rod 50 itself serving to avoid movements of the workpiece 1 in the lapping ring 5. Advantageously, the impression E is made in the center of the upper surface of the part to be lapped 1. In addition, a mass 30 is positioned on the rod 50 so as to press the part to be lapped 1 against the lapping plate 3 while maintaining a constant holding force and so as to keep the pointed end 60 of the rod 50 in the cavity E of the part to be lapped 1. The mass 30 can be e positioned at the end of the rod 50, outside of the external envelope 10, that is to say above the cover 20. The mass 30 can alternatively be positioned in the external envelope 10, that is to say under the cover 20.

The outer casing 10 can simply be positioned above the lapping ring 5 or else be rigidly fixed to it, by any fixing means known to those skilled in the art. For example, the lapping ring may have on its upper part a reduced outside diameter over a certain height (as in FIG. 4) so as to facilitate the placing and holding in position of the outer casing 10 on the lapping ring 5. Thus, the cylindrical wall 15 may have an internal diameter slightly greater (or equal to the clearance) than the reduced external diameter of the upper part of the lapping ring 5 to allow its insertion therein and guarantee that this position is maintained during the lapping operations. According to an alternative, the lapping ring 5 may have on its upper part an internal diameter increased over a certain height. Thus, the cylindrical wall 15 may be of an external diameter slightly less (or equal to the clearance apart) than the internal diameter increased by the upper part of the lapping ring 5 to allow its insertion therein and guarantee the maintenance of this position during running-in operations. It is also possible to provide an increased internal diameter or a reduced external diameter on the external casing 10, with a lapping ring 5 without modification of diameter in its upper part, for the connection with the external casing 10, having the same positioning and holding functions of these two parts.

The invention also relates to a prowler which comprises a lapping plate with a lapping surface, constituted for example by an abrasive such as sandpaper. The prowler also includes an articulated arm driving the support device according to one of the preceding characteristics. The support device is held in the articulated arm, for example by means of rollers. The prowler according to the invention allows better lapping quality than prowlers of the prior art thanks to the support device. In addition, no manual recovery is necessary, which also saves time.

Furthermore, the invention also relates to a method of lapping at least one part to be lapped for which:

- the part to be lapped is positioned on the lapping plate;

- The rod is positioned with the associated mass so that the pointed end of the rod is engaged on the part to be lapped, preferably in an impression of the part to be lapped, the rod being guided by the passage drilled in the outer envelope;

- the outer envelope is made to describe movements, for example movements in the form of an "eight", on the lapping plate, by means of the articulated arm and the rotating lapping plate.

Thus, this method is faster than the methods of the prior art since it does not require any manual recovery. In addition, the force induced by the mass on the lapping part being constant and the positioning of the lapping part in the lapping ring being almost constant during lapping (few relative movements of the lapping part with respect to the lapping ring), thanks to the use of the imprint of the lapping part, the pointed end of the rod and the guidance of the rod in the drilled passage, the quality of lapping is greatly improved.

Advantageously, the mass positioned on the rod can be adapted to the material of the part to be lapped and to the expected finish of lapping. Thus, for example, for a hard material relative to another material which is softer, a greater mass will be necessary for the same expected lapping finish.

According to a preferred embodiment of the invention, it is possible to position several parts to be lapped on the lapping plate, each part to be lapped then being engaged with a different rod and on each of these rods is positioned a mass which does not is not necessarily related to other masses. Each of the rods then crosses a different drilled passage in the outer casing. In this way, each of the parts to be lapped is held, independently of the others, against the lapping surface.

Preferably, a separate mass can be positioned on each of the rods. Therefore, when several parts to be lapped are lapped at the same time in the prowler and the materials of these different parts are different, it is possible to choose different masses on the different rods.

According to another alternative, a common mass can be positioned for all the rods. This can simplify the assembly of the assembly in the case where the samples have the same characteristics and dimensions.

Preferably, the method can also include a preliminary step in which the impression is made in the part to be lapped, so as to facilitate the maintenance of the part to be lapped by the rod. The rod can then be positioned in the impression. The impression makes it possible to maintain the tip of the rod in the sample during running-in.

Preferably, this imprint can be a notch whose depth is between 1 and 3 mm. For example, the notch can be a cylindrical notch or preferably a pointed notch adapted to the shape of the pointed end of the rod. Thus, the retention of the part to be lapped by the rod is improved and consequently, the lapping is also improved. Preferably, the depth of the notch is of the order of 2 mm in order to ensure good retention of the rod in the workpiece and to avoid any risk of the rod coming out of the workpiece, which could compromise the running-in operation.

In addition, when the part to be lapped is substantially a parallelepiped, the imprint is preferably at the center of the upper face of this parallelepiped, so as to make it easier to hold the rod in position on the part to be lapped. Indeed, by being thus in the center of the surface, the part to be lapped is correctly balanced around the axis of the rod, which can then be an axis of rotation during movements.

Examples

The system and method according to the invention allow a significant saving in running-in time compared to manual running-in. In fact, the system adapted according to the invention on an ESCIL LM 300 ™ type prowler makes it possible to test, for example, 5 parts to be lapped simultaneously, each of the parts to be lapped having the shape of a parallelepiped with a contact face with the plate. grinding time of 30 ^* 45 mm ² , in just 20 minutes for a flatness and roughness compatible with observation under a microscope, while it takes on average between 15 and 30 minutes per part to be lapped in manual lapping operation. By a flatness and a roughness compatible with observation under a microscope, it is meant that the flatness and the roughness are controlled by the use of a net rule known to those skilled in the art.

The system and method according to the invention allow an increased gain in quality compared to the usual automatic running-in operations. Indeed, the rate of failure or interruption of lapping is close to zero by the system or method according to the invention, while the usual prowlers regularly have overlaps of parts to be lapped causing an interruption. In addition, this lack of intervention, synonymous with good operation, also results in a very good quality of the running-in finish of all the parts to be run-in, without requiring manual rework.

Claims

1. Lapping parts support device (1) for a prowler, said device comprising a lapping ring (5), an external casing (10), said external casing (10) being arranged on said lapping ring (5), said outer casing (10) comprising at least one pierced passage (40), said outer casing (10) being configured to contain at least one lapping part (1), characterized in that the device comprises a rod (50) ending in a pointed end (60), the axis of said rod (50) being substantially vertical, said rod (50) passing through said outer casing (10) through said pierced passage (40), the pointed end (60) of said rod (50) being intended to be positioned on said lapping part (1) and a mass (30) being positioned on said rod (50).

2. Device according to claim 1 for which said external casing (10) is configured to contain several lapping parts (1), preferably between 4 and 10 lapping parts (1), and for which said device comprises several rods (50 ), each of said rods (50) passing through a different drilled passage (40) in said outer casing (10).

3. Device according to one of the preceding claims, in which said mass (30) is positioned outside of said external envelope (10).

4. Device according to one of claims 1 or 2, for which said mass (30) is positioned in said outer casing (10).

5. Device according to one of the preceding claims, in which said external envelope (10) has a cylindrical shape closed by a cover, said pierced passage being produced in said cover.

6. Device according to one of the preceding claims, in which said running-in ring (5) and said outer casing (10) are produced by the same single piece.

7. prowler comprising a lapping plate (3) with a lapping surface, an articulated arm (4) driving the support device according to one of the preceding claims, for which the support device is positioned so that said face to be lapped of said lapping part (1) is positioned against the lapping plate (3).

8. Lapping method for at least one lapping part (1) using a prowler according to claim 7 for which:

- Positioning said part to be lapped (1) on said lapping plate (3);

- Positioning said outer casing (10) around said lapping part (1), said outer casing (10) being positioned above said lapping ring (5); - Positioning said rod (50) with said mass (30) associated so that said pointed end (60) of said rod (50) is in contact with said workpiece (1), said rod (50) being guided by said pierced passage (40) in said outer casing (10);

- It is said that said outer shell (10) movements on said lapping plate (3), through said articulated arm (40), said lapping plate (3) being itself in motion.

9. Method according to claim 8, in which said mass (30) positioned on said rod (50) is adapted to the material of said part to be lapped (1) and to the expected finish of said lapping.

10. Method according to one of claims 8 or 9, for which several lapping parts (1) are positioned on said lapping plate (3), for which each lapping part (1) is engaged with a rod (50 ) different .

1 1. Method according to claim 10, in which a separate mass (30) is positioned on each of the rods (50).

12. Method according to claim 10, for which a common mass (30) is positioned for all the rods (50).

13. Method according to one of claims 8 to 12, comprising a prior step of producing an imprint (E) in said lapping part (1), said rod being positioned in said imprint (E).

14. Method according to one of claims 8 to 13, wherein said imprint (E) is a notch with a depth between 1 and 3 mm.