CH718365A2 - Method of manufacturing a cutting tool with lubrication holes and a cutting tool with lubrication holes. - Google Patents

Abstract

The invention relates to a method for manufacturing a cutting tool (10) with lubrication orifices of complex shapes, comprising the steps of: producing a polymer insert, overmolding a body of the cutting tool ( 10) with the polymer insert by injection into a mould, elimination of the polymer insert, so as to form within the body of the cutting tool (10) lubrication orifices whose shape is complementary to that part of the insert, machining the body of the cutting tool (10) on at least one part called the "active part", depositing an abrasive coating on a surface of the active part of the body of the cutting tool (10). The invention also relates to a cutting tool (10) having lubrication holes.

Description

Technical field of the invention

The invention falls within the field of mechanical machining, and in particular the field of machining tools and accessories. The invention relates more particularly to a method of manufacturing a cutting tool with lubrication orifices of complex shapes and a cutting tool with lubrication orifices of complex shapes.

The cutting tool according to the invention is intended in particular for machining a part, in particular a watch component.

Technology background

[0003] In the field of mechanical machining, the objective of lubrication is, on the one hand, the lubrication of the interface between the cutting tool and the machined part to reduce friction, on the other hand, the refrigeration of said interface. Another objective of lubrication is to evacuate the shavings as the cutting operation progresses, that is to say during machining. Overall, lubrication enables efficient machining.

[0004] Some cutting tools have internal lubrication orifices in order to increase the effects of lubrication during machining.

[0005] Cutting tools comprising a body in which lubrication orifices are machined, such as an axial through-bore and channels extending radially between the bore and the active surface, are known from the state of the art. of the cutting tool.

[0006] The body is generally made of high-strength steels and galvanic deposition of abrasive grains is carried out on the active surface.

[0007] These tools notably have the disadvantage of being complex and very expensive to produce. Indeed, the material which constitutes them being hard, their machining is complex.

[0008] In addition, the hardness of high-strength steels limits the machining of these cutting tools, and in particular of their lubrication orifices, to the production of relatively simple shapes.

[0009] For these reasons, the use of these cutting tools having lubrication orifices is quite limited. For example, they are limited to use in grinding applications, for parts made of materials with a hardness below a certain threshold only.

Summary of the invention

The invention solves the aforementioned drawbacks by proposing a solution allowing the production of a cutting tool, the body of which has lubrication orifices of complex shapes.

To this end, the present invention relates to a method of manufacturing a cutting tool with lubrication orifices of complex shapes, characterized in that it comprises the steps of: production 320 of a polymer insert, overmolding 310 of a body of the cutting tool with the polymer insert by injection into a mold, elimination 320 of the polymer insert, so as to form within the body of the cutting tool lubrication orifices whose shape is complementary to that of a part of the insert, sintering 330 of the body of the cutting tool 10, machining 340 of the body of the cutting tool on at least one part called the "active part", depositing an abrasive coating 350 on a surface of the active part of the body of the cutting tool, said surface being called “active surface”.

[0012] Thanks to these characteristics, the lubrication orifices can have complex container shapes.

Thus, new hard materials whose machining proved to be too complex or expensive, or even impossible, with existing cutting tools can be machined with a cutting tool according to the present invention. Such hard materials consist for example of ceramics, such as silicon nitride, zirconium oxide, or of sapphire, alumina or any hard metal.

[0014] In addition, the cutting tools according to the present invention can be used to carry out milling operations on hard materials unlike the cutting tools of the state of the art, since the lubrication orifices can be made in such a way to optimize said lubrication.

[0015] In particular embodiments, the invention may also comprise one or more of the following characteristics, taken in isolation or in all technically possible combinations.

In particular embodiments, the insert is made of a polymer chosen from plasticized polyvinyl butyral (known by the acronym in English "PVB" for "Polyvinyl butyral"), Cellulose Acetate Butyrate plasticized (known by the acronym „CAB“), and poly butyl methacrylate type acrylic resin (known by the acronym „PBMA“).

In particular embodiments, the step 320 of removing the insert is implemented by introducing the insert into a bath.

[0018] In particular embodiments, the insert is produced by an additive manufacturing method.

According to another object, the present invention also relates to a cutting tool comprising a body comprising lubrication orifices and having a gripping part intended to be fixed to a tool chuck and an active part comprising an active surface. Along the active surface extend helical grooves, said grooves being connected to a central recess extending axially in the body of the tool by radial channels. Said central recess extends between a lubricant inlet opening opposite a lubricant discharge opening.

[0020] In particular embodiments, the peripheral grooves extend helically between a first end opening onto a free end of the cutting tool and a second end opening close to the gripping part of the cutting tool. , i.e. closer to the gripping part than to the free end of the cutting tool.

[0021] In particular embodiments, the evacuation opening is configured so as to generate a venturi effect.

In particular embodiments, the active surface has substantially a cylindrical shape of revolution comprising a peripheral surface and an end surface, said end surface defining the free end of the body of the cutting tool. . The evacuation opening leads to a countersink, said cutting tool comprising end grooves extending radially on the end surface, from the countersink to the peripheral surface.

In particular embodiments, each radial channel extends in length in a direction forming an acute angle with a longitudinal axis of the body of the cutting tool, the angle being oriented towards the free end of said body. of the cutting tool.

[0024] Preferably, the radial channel extends in a direction forming an angle of 45 degrees, plus or minus 10 degrees, with the longitudinal axis of the body of the cutting tool.

This characteristic is advantageous in that it allows better distribution of the lubricant around the body of the cutting tool.

In particular embodiments, each radial channel extends in length has a helical shape.

[0027] This feature makes it possible to further improve the distribution of the lubricant around the body of the cutting tool.

Brief description of figures

Other characteristics and advantages of the invention will appear on reading the following detailed description given by way of non-limiting example, with reference to the appended drawings in which: FIG. 1 represents a flowchart of an example of implementation of the method of manufacturing a cutting tool with lubrication orifices of complex shapes according to the invention; FIG. 2 represents a perspective view of an embodiment of an insert for implementing the method of FIG. 1; FIG. 3 represents a perspective view of an embodiment of a cutting tool obtained by implementing the method of FIG. 1; FIG. 4 represents a cross-sectional view of the cutting tool of FIG. 3 on which the insert of FIG. 2 is overmolded.

Detailed description of the invention

The present invention relates to a method of manufacturing a cutting tool 10 with lubrication orifices of complex shapes and a cutting tool 10 with lubrication orifices of complex shapes.

In the present description, a preferred application of the invention is described in which the cutting tool 10 is a machining tool, for example for grinding, drilling or milling, intended to be driven in rotation. to machine a part.

As shown in the flowchart of Figure 1, the method according to the present invention comprises a preliminary step 320 of producing an insert 20 of polymer material.

The insert 20 is illustrated in a preferred embodiment in Figure 2, and is made, for example by molding or by additive manufacturing, so as to have a negative shape of that of all or part of a cutter body 10.

In other words, the insert 20 has a shape such that it is complementary to that of the body of the cutting tool 10 which is intended to be manufactured by the method according to the invention.

Still in other words, the shape of the insert 20 is defined according to the desired shape of the cutting tool 10, since said desired shape of the cutting tool 10 is obtained by subtracting the shape of the insert 20, as described in more detail below.

[0035] The insert 20 is made of a polymer material, for example plasticized polyvinyl butyral (known by the acronym "PVB"), plasticized Cellulose Acetate Butyrate (known by the acronym "CAB"), or resin Poly butyl methacrylate type acrylic (known by the acronym „PBMA“).

[0036] Once the insert 20 has been made, the body of the cutting tool 10 is overmolded with said insert 20 during an overmolding step 310 shown in the sectional view of FIG. 4. More particularly, when this overmolding step 310, a mixture of powder, for example tungsten or other metals, and binder, for example polymer or metal, previously produced is injected into a mold in which the insert 20 is placed.

The powder and the binder are advantageously chosen so as to form a body of the tool made of a hard metallic material, once the molding step 310 has been completed.

Next, a step 320 of removing the insert 20 is carried out, so as to form within the body of the cutting tool 10 lubrication orifices whose shape is complementary to that of a part of insert 20.

During this step 320 of removing the insert 20, the assembly resulting from the overmolding step 310, that is to say the insert 20 and the cutting tool 10 cooperating with the with each other, is introduced into a bath, preferably of alcohol heated to 80°C.

The alcohol bath has the effect of dissolving the insert 20 so as to obtain only the cutting tool 10.

It should be noted that any method that can eliminate the material constituting the insert 20 without degrading that constituting the body of the cutting tool 10 can be implemented in the step 320 of eliminating the insert 20.

The manufacturing method according to the invention then comprises a step 330 of sintering the body of the cutting tool 10, consisting in heating said body of the cutting tool 10 so as to form the cohesion of the material which constitutes and to harden it.

The body of the cutting tool 10 is substantially cylindrical in shape and extends along a longitudinal axis. It comprises a first part 11 intended to be fixed to a tool chuck, connected to a second part 12 intended to be in contact with the workpiece. The first part 11 is here called "grip part" 11 and the second part 12 is called "active part" 12, said active part 12 comprising an external surface called "active surface".

As shown in Figure 3, at least the active part 12 of the body of the cutting tool 10 advantageously comprises lubrication orifices at the end of the step 320 of removing the insert 20, said orifices being of shapes complementary to those of portions of the insert 20 described in detail below, insofar as they are generated by the subtraction of said portions within the body of the cutting tool 10.

Thus, the lubrication orifices can have complex shapes, depending on the shapes taken by said portions of the insert 20.

It should be noted that the shape of the insert 20, and in particular of said portions of the insert 20, can be very complex when the latter is made by additive manufacturing.

The active part 12 of the body of the cutting tool 10 is then machined during a machining step 340 of the body of the cutting tool 10.

During this step, the active part 12 is ground so as to obtain a surface condition suitable for carrying out a step of depositing an abrasive coating 350, in which the active surface of the body of the tool cutting 10 is covered with a layer of abrasive, for example by galvanic deposition.

The gripping part 11 can be machined during the machining step so as to be adapted to cooperate in attachment with a tool chuck.

[0050] Alternatively, the mold can be of such a shape that the gripping part 11 is molded during the overmolding step 310.

[0051] Preferably, the active surface has substantially the shape of a cylinder of revolution comprising a peripheral surface 120 and an end surface 121, said end surface 121 defining the free end of the body of the cutting tool 10, as shown in the perspective view of Figure 3.

Also, in the preferred embodiment shown in the figures, the insert 20 is shaped so that the cutting tool 10 has at least in its active part, a central recess 13 of circular section extending axially inside the body of the tool, between a first opening (not shown in the figures) intended to receive lubricant, called the "intake opening", located towards or in the gripping part 11 of the tool , and a second opening, called "discharge opening" 130, intended to evacuate the lubricant, leading to the free end.

The evacuation opening 130 is advantageously configured so as to generate a venturi effect. For this purpose, the central recess 13 has, at the level of the evacuation opening 130, a radial lip 131 arranged so as to gradually reduce the section of said central recess 13, as shown in the sectional view of FIG. .

[0054] Advantageously, the discharge opening 130 opens onto the free end by a countersink 123, so that the section of the central recess 13 increases gradually from the lip 131 to said free end. The technical effects of these features are described below.

Advantageously, the active part comprises end grooves 122 extending radially on the end surface 121, from the countersink 123 to the peripheral surface 120. These end grooves 122 are distributed angularly around the longitudinal axis of the body of the cutting tool 10 in a regular manner, as shown in Figure 3.

The end grooves 122 make it possible to evenly distribute radially the flow of lubricant expelled through the discharge opening 130 during the operation of the cutting tool 10.

Again advantageously, as also shown in Figure 3, the active part comprises peripheral grooves 124 extending helically on the peripheral surface 120, between a first end opening onto the free end of the cutting tool 10, that is to say on the end surface 121, and a second end emerging close to the gripping part 11 of the cutting tool 10. In other words, the second end of the peripheral grooves 124 is closer to the gripping part 11 than the free end of the cutting tool 10.

These peripheral grooves 124 are angularly distributed in a regular manner around the longitudinal axis of the body of the cutting tool 10.

As illustrated in Figures 3 and 4, the cutting tool 10 comprises radial channels 132 connecting the central recess 13 to the peripheral grooves 124. More specifically, the cutting tool 10 comprises as many radial channels 132 as peripheral grooves 124, each radial channel 132 opening out at the second end of a peripheral groove 124.

[0060] The term channel defined in the present text means a conduit closed radially and emerging axially.

[0061] Thus, during the rotation of the cutting tool 10, during the operation of the cutting tool 10, part of the lubricant circulating in the central recess 13 is expelled by the radial channels 132, generating a flow of lubricant within each of the peripheral grooves 124.

These characteristics participate in optimizing the lubrication and the cooling of the cutting tool 10 and of the machined part, and therefore allow the machining of parts made of very hard materials, of the ceramic type, such as silicon nitride. , zirconium oxide, etc., or sapphire or other stones, alumina, or any hard metal.

[0063] The fact that the second end of the peripheral grooves 124 is closer to the gripping part 11 than to the free end of the cutting tool 10 makes it possible to ensure that the majority or the whole of the surface active is lubricated during the operation of the cutting tool 10.

Preferably, each radial channel 132 extends in length in a direction forming an acute angle, for example 45 degrees, with the longitudinal axis of the body of the cutting tool 10, said acute angle being oriented towards the free end of said body of the cutting tool 10.

[0065] In another example, the angle can be of a value between 35 and 55 degrees.

This characteristic is advantageous in that it allows better distribution of the lubricant around the body of the cutting tool 10.

Again preferably, the direction in which each radial channel 132 extends in length has a helical shape. In other words, each channel has a curved shape.

This feature makes it possible to further improve the distribution of the lubricant around the body of the cutting tool 10, and thus to further limit the temperature increase at the interface between the cutting tool 10 and the workpiece. machined, during machining, which leads to avoiding premature wear of the galvanic deposit.

[0069] The lip 131 has the effect of increasing the expulsion pressure of the lubricant at the level of the evacuation opening 130 and thus of reducing or eliminating the loss of lubricant pressure within the central recess. 13 generated by the radial channels 132. The countersink 123 has the effect of ensuring a homogeneous radial distribution of the flow of lubricant expelled.

In the present embodiment of the invention and as illustrated in particular in Figure 2, the insert 20 has a body of the insert 20 in the form of a blind hollow tube 21 of circular section intended to contain and form the body of the cutting tool 10.

The hollow tube 21 is connected to a central rod 22 intended to form the central recess 13, by radial rods 23 intended to form the radial channels 132.

The insert 20 also comprises a projection 24 extending helically on an inner peripheral face of the hollow tube 21, from each radial rod 23 to an inner face of a bottom wall of said hollow tube 21. The projections 24 are intended to form the peripheral grooves 124.

The central rod 22 comprises, at the end by which it is connected to the bottom wall, a reduction in section defining a radial groove 25 intended to form the lip 131.

The radial groove 25 is connected to the inner face of the bottom wall by a fillet 26 intended to form the countersink 123.

Finally, projections 27 extend radially on the internal face of the bottom wall, from the fillet 26 to the internal peripheral face 120 of the hollow tube 21. These projections 27 are intended to form the grooves of end 122 when carrying out the manufacturing method according to the invention.

It should be noted that the present invention can be applied to a cutting tool intended to carry out drilling, milling or any other mechanical machining operation and to the method of this cutting tool.

Claims (10)

1. A method of manufacturing a cutting tool (10) with lubrication orifices of complex shapes, characterized in that it comprises the steps of: – production 320 of an insert (20) in polymer, – overmolding 310 of a body of the cutting tool (10) with the polymer insert (20) by injection into a mould, – elimination 320 of the insert (20) made of polymer, so as to form within the body of the cutting tool (10) lubrication orifices whose shape is complementary to that of a part of the insert ( 20), – 330 sintering of the body of the cutting tool (10), – machining 340 of the body of the cutting tool (10) on at least one part called the “active part”, – deposition of an abrasive coating 350 on a surface of the active part of the body of the cutting tool (10). 2. Manufacturing process according to claim 1, in which the insert (20) is made of plasticized polyvinyl butyral, plasticized Cellulose Acetate Butyrate, or polybutyl methacrylate type acrylic resin. 3. Manufacturing method according to one of claims 1 to 2, wherein the step 320 of removing the insert (20) is implemented by introducing the insert (20) into a bath. 4. Manufacturing process according to one of claims 1 to 3, wherein the insert (20) is produced by an additive manufacturing method. 5. Cutting tool (10) characterized in that it comprises a body having lubrication orifices and having a gripping part (11) intended to be fixed to a tool chuck and an active part comprising an active surface the along which extend helical grooves, said grooves being connected to a central recess (13) extending axially in the body of the tool by radial channels (132), said central recess (13) extending between a lubricant inlet opening opposite a lubricant outlet opening (130). 6. Cutting tool (10) according to claim 5, in which the peripheral grooves (124) extending helically between a first end opening onto a free end of the cutting tool (10) and a second end opening near of the gripping part (11) of the cutting tool (10), i.e. closer to the gripping part (11) than to the free end of the cutting tool (10) . 7. Cutting tool (10) according to one of claims 5 or 6, wherein the discharge opening (130) is configured so as to generate a venturi effect. 8. Cutting tool (10) according to one of claims 5 to 7, wherein the active surface has substantially a cylindrical shape of revolution comprising a peripheral surface (120) and an end surface (121), said surface end (121) defining the free end of the body of the cutting tool (10), and in which the discharge opening (130) leads to a countersink (123), said cutting tool (10) comprising end grooves (122) extending radially on the end surface (121), from the countersink (123) to the peripheral surface (120). 9. Cutting tool (10) according to one of claims 5 to 8, wherein each radial channel (132) extends lengthwise in a direction forming an acute angle with a longitudinal axis of the body of the cutting tool (10), said acute angle being oriented towards the free end of said cutting tool body (10). 10. A cutting tool (10) according to claim 9, wherein the direction in which each radial channel (132) extends in length has a helical shape.