Method for manufacturing a cutting tool having a lubrication opening of complex shape and cutting tool having a lubrication opening of complex shape

Abstract

The invention relates to a method for manufacturing a cutting tool (10) having lubrication orifices of complex shape, the method comprising the following steps: - producing 320 an insert (20) made of a polymer, - overmolding 310 the body of the cutting tool (10) by the insert (20) made of a polymer by injection into a mold, - removing 320 the insert (20) made of a polymer in order to form lubrication orifices in the body of the cutting tool (10), the shape of these lubrication orifices being complementary to the shape of a part of the insert (20), - machining 340 the body of the cutting tool (10) on at least one part, referred to as the "active part", - depositing 350 an abrasive coating on the surface of the active part of the body of the cutting tool (10).

Description

Technical Field

[0001] The present invention relates to the field of mechanical processing, and in particular to the field of machining tools and accessories. More specifically, the present invention relates to a method for manufacturing a cutting tool having a lubrication hole of a complex shape and a cutting tool having a lubrication hole of a complex shape.

[0002] The cutting tool according to the invention is particularly intended for machining parts, in particular timepiece components. Background Art

[0003] In the field of machining, the purpose of lubrication is, on the one hand, to lubricate the interface between the cutting tool and the machined part to reduce friction, and on the other hand, to cool the interface. Another purpose of lubrication is to evacuate chips as the cutting operation proceeds (i.e., during machining). Overall, lubrication makes efficient machining possible.

[0004] Some cutting tools include internal lubrication ports to enhance lubrication during machining.

[0005] Cutting tools are known from the prior art which comprise a body in which a lubrication aperture is machined, such as a through axial hole and a channel extending radially between the hole and an active surface of the cutting tool.

[0006] The body is usually made of high-strength steel and an electrodeposition of abrasive particles is produced on the active surface.

[0007] These tools have the drawback of being very complex and very costly to produce in particular. In fact, the material they are made of is hard and their processing is complicated.

[0008] Furthermore, the hardness of high-strength steels limits the machining of these cutting tools (and particularly their lubrication ports) to the production of relatively simple shapes.

[0009] For these reasons, the use of these cutting tools with lubrication ports is rather limited. For example, they are limited to use in grinding applications only on parts made of materials with a hardness below a certain threshold. Summary of the invention

[0010] The present invention solves the above mentioned drawbacks by proposing a solution for producing a cutting tool in which the body has lubrication orifices of complex shape.

[0011] To this end, the present invention relates to a method for producing a cutting tool having a lubrication opening of complex shape, characterized in that the method comprises the following steps:

[0012] - Production of 320 inserts made of polymer,

[0013] - overmolding 310 the body of the cutting tool by an insert made of a polymer by injection into a mold,

[0014] - removing 320 an insert made of polymer in order to form lubrication orifices in the body of the cutting tool, the shape of these lubrication orifices being complementary to the shape of a portion of the insert,

[0015] - sintering 330 the body of the cutting tool 10,

[0016] - machining 340 the body of the cutting tool on at least one portion, referred to as the "active portion",

[0017] - Deposition of an abrasive coating 350 on the surface of the active part of the body of the cutting tool, said surface being called "active surface".

[0018] Due to these features, the lubrication port can have a complex receiving shape.

[0019] Thus, new hard materials can be machined with the cutting tool according to the invention, which have proved to be too complicated or cumbersome or even impossible to machine with existing cutting tools. Such hard materials consist, for example, of ceramics such as silicon nitride, zirconium oxide or sapphire, aluminum oxide or any hard metal.

[0020] Furthermore, unlike cutting tools of the prior art, the cutting tool according to the invention can be used for milling operations on hard materials, since lubrication orifices can be produced in order to optimize the lubrication.

[0021] In a specific embodiment, the present invention may further include one or more of the following features, which are understood in isolation or in any technically possible combination.

[0022] In a specific embodiment, the insert is made of a polymer selected from plasticized polyvinyl butyral (referred to by the acronym "PVB"), plasticized cellulose acetate butyrate (referred to by the acronym "CAB"), and polybutyl methacrylate acrylic resin (referred to by the acronym "PBMA").

[0023] In a specific embodiment, the step of removing 320 the insert is performed by introducing the insert into a bath.

[0024] In a particular embodiment, the insert is produced by an additive manufacturing method.

[0025] According to a further object, the invention relates to a cutting tool which can be produced by implementing a method as described above, said cutting tool comprising a body comprising a lubrication orifice and having a clamping portion intended to be fastened to a tool-holder chuck and an active portion comprising an active surface. A helical groove extends along the active surface, said groove being connected via a radial channel to a central hollow extending axially into the body of the tool. The central hollow extends between a lubricant inlet opening opposite a lubricant discharge opening.

[0026] In a particular embodiment, the peripheral groove extends helically between: a first end, which opens into the free end of the cutting tool; and a second end, which opens into the vicinity of the clamping portion of the cutting tool, ie closer to the clamping portion than the free end of the cutting tool.

[0027] In a particular embodiment, the discharge opening is configured so as to produce a Venturi effect.

[0028] In a particular embodiment, the active surface has substantially a rotational cylindrical shape comprising a peripheral surface and an end surface, the end surface defining a free end of the body of the cutting tool. The discharge opening opens into the recess, the cutting tool comprising an end groove extending radially from the recess to the peripheral surface on the end surface.

[0029] In a particular embodiment, each radial channel extends lengthwise in a direction forming an acute angle with the longitudinal axis of the body of the cutting tool, the angle being oriented towards the free end of said body of the cutting tool.

[0030] Preferably, the radial channel extends in a direction forming an angle of 45 degrees (± 10 degrees) with the longitudinal axis of the body of the cutting tool.

[0031] This feature is advantageous because it enables the lubricant to be better distributed around the body of the cutting tool.

[0032] In a particular embodiment, each longitudinally extending radial channel has a helical shape.

[0033] This feature enables the distribution of the lubricant around the body of the cutting tool to be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further characteristics and advantages of the invention will emerge from a reading of the following detailed description given by way of non-limiting example with reference to the accompanying drawings, in which:

[0035] - Figure 1 A logic diagram representing an example of an embodiment of a method according to the present invention for manufacturing a cutting tool having a lubrication orifice of complex shape;

[0036] - Figure 2 Indicates that it is used to implement Figure 1 A perspective view of an example embodiment of an insert of the method;

[0037] - Figure 3 Indicates that by implementing Figure 1 A perspective view of an example embodiment of a cutting tool obtained by the method of

[0038] - Figure 4 express Figure 3 Transverse section of the cutting tool in Figure 2 The insert in is overmolded onto the cutting tool. DETAILED DESCRIPTION

[0039] The present invention relates to a method for manufacturing a cutting tool 10 having a lubrication port having a complex shape and a cutting tool 10 having a lubrication port having a complex shape.

[0040] In the present specification, a preferred application of the invention is described, in which the cutting tool 10 is a machining (eg grinding) tool, which is intended to be rotated to machine a part.

[0041] like Figure 1 As shown in the logic diagram in , the method according to the invention comprises a preliminary step of producing 320 an insert 20 made of polymer material.

[0042] Insert 20 in Figure 2 It is illustrated in the preferred embodiment example in and is produced, for example, by molding or by additive manufacturing, so as to have the negative shape of the shape of all or part of the body of the cutting tool 10 .

[0043] In other words, the insert 20 has a shape such that it is complementary to the shape of the body of the cutting tool 10 intended to be manufactured by the method according to the invention.

[0044] In other words again, the shape of the insert 20 is defined according to the sought shape of the cutting tool 10 , considering that the sought shape of the cutting tool 10 is obtained by subtracting the shape of the insert 20 , as described in more detail below.

[0045] The insert 20 is made of a polymer material such as plasticized polyvinyl butyral (referred to by the acronym “PVB”), plasticized cellulose acetate butyrate (referred to by the acronym “CAB”), and polybutyl methacrylate acrylic resin (referred to by the acronym “PBMA”).

[0046] Once the insert 20 has been produced, the cutting tool 10 is overmolded with said insert 20 during an overmolding step 310, which is performed at Figure 4 More specifically, during this overmolding step 310 , a previously produced powder mixture (for example tungsten or another metal) and a binder (for example polymer or metal) are injected into a mold in which the insert 20 is arranged.

[0047] The powder and the binder are advantageously selected so as to form a tool body of hard metal material once the overmolding step 310 has been completed.

[0048] Then, a step of removing 320 the insert 20 is performed so as to form lubrication apertures in the body of the cutting tool 10 , the shapes of which are complementary to the shape of a portion of the insert 20 .

[0049] During this step of removing 320 the insert 20 , the assembly resulting from the overmoulding step 310 , ie the insert 20 and the cutting tool 10 cooperating with each other, is introduced into a bath, preferably an alcohol bath heated to 80° C.

[0050] The alcohol bath has the effect of dissolving the insert 20 so that only the cutting tool 10 is obtained.

[0051] It is noted that in the step of removing 320 the insert 20 , any method capable of removing the constituent material of the insert 20 without degrading the constituent material of the cutting tool 10 may be implemented.

[0052] The manufacturing method according to the invention then comprises a step of sintering 330 the body of the cutting tool 10 , which step comprises heating said body of the cutting tool 10 in order to form cohesion and harden said constituent materials.

[0053] The body of the cutting tool 10 is of substantially cylindrical shape and extends along a longitudinal axis. It comprises a first portion 11 intended to be fastened to a tool holder chuck, connected to a second portion 12 intended to come into contact with the part to be machined. The first portion 11 is referred to herein as the "clamping portion" 11, and the second portion 12 is referred to as the "active portion" 12, comprising an outer surface referred to as the "active surface".

[0054] like Figure 3 As shown in , after the step of removing 320 the insert 20, at least the active portion 12 of the body of the cutting tool 10 advantageously comprises lubrication orifices having a shape complementary to the shape of the portion of the insert 20 as described in detail below, provided that these orifices are produced by subtracting said portion from the body of the cutting tool 10.

[0055] Thus, depending on the shape adopted by the portion of the insert 20 , the lubrication aperture may have a complex shape.

[0056] It is worth noting that when the insert 20 is produced by additive manufacturing, the shape of the insert 20 (and in particular the shape of the portion of the insert 20 ) can be very complex.

[0057] Then, during a step of machining 340 the body of the cutting tool 10 , the active portion 12 of the body of the cutting tool 10 is machined.

[0058] During this step, the active portion 12 is trimmed in order to obtain suitable surface conditions to carry out a step of depositing an abrasive coating 350 , in which the active surface of the body of the cutting tool 10 is covered with an abrasive coating, for example by electrodeposition.

[0059] The clamping portion 11 may be machined during a machining step so as to be adapted for fastening cooperation with a tool holder chuck.

[0060] Alternatively, the mold may have a shape such that the clamping portion 11 is molded during the overmolding step 310 .

[0061] Preferably, the active surface has substantially a shape of a revolution cylinder comprising a peripheral surface 120 and an end surface 121 defining the free end of the body of the cutting tool 10, as in Figure 3 shown in the perspective view.

[0062] Moreover, in the example of a preferred embodiment represented in the figures, the insert 20 is shaped so that the cutting tool 10 has, at least in its active part, a central hollowing-out 13 of circular cross-section, which extends axially inside the body of the tool between: a first opening (not shown in the figures) intended to receive lubricant, referred to as the “inlet opening”, which is located towards the clamping part 11 of the tool or in the clamping part 11 of the tool; and a second opening intended to discharge the lubricant, referred to as the “discharge opening” 130, which leads to the free end.

[0063] The discharge opening 130 is advantageously configured so as to produce a Venturi effect. For this purpose, the central hollowing 13 has a radial lip 131 at the discharge opening 130, which is arranged so as to gradually reduce the cross section of the central hollowing 13, as in Figure 4 shown in the cross-sectional view in .

[0064] Advantageously, the discharge opening 130 leads to the free end via the recess 123, so that the cross section of the central hollow 13 increases gradually from the lip 131 to said free end. The technical effects of these features are described below.

[0065] Advantageously, the active portion comprises an end groove 122 which extends radially from the recess 123 on the end surface 121 to the peripheral surface 120. These end grooves 122 are angularly distributed around the longitudinal axis of the body of the cutting tool 10 in a regular manner, such as Figure 3 As indicated in .

[0066] The end grooves 122 make it possible to evenly radially distribute the flux of lubricant discharged by the discharge openings 130 during operation of the cutting tool 10 .

[0067] Also, advantageously, Figure 3 As also shown in FIG. 1 , the active portion includes a peripheral groove 124 that extends spirally on the peripheral surface 120 between: a first end that opens toward the free end of the cutting tool 10 (i.e., on the end surface 121); and a second end that opens toward the vicinity of the clamping portion 11 of the cutting tool 10. In other words, the second end of the peripheral groove 124 is closer to the clamping portion 11 than the free end of the cutting tool 10.

[0068] These peripheral grooves 124 are angularly distributed in a regular manner around the longitudinal axis of the body of the cutting tool 10 .

[0069] As in Figure 3 and Figure 4 As illustrated, the cutting tool 10 includes radial channels 132 connecting the central recess 13 to the peripheral groove 124. More specifically, the cutting tool 10 includes the same number of radial channels 132 as the peripheral groove 124, each of which opens to the second end of the peripheral groove 124.

[0070] The term "channel" in this document defines a radially closed and axially open conduit.

[0071] Thus, during rotation of the cutting tool 10 , during operation of the cutting tool 10 , a portion of the lubricant circulating in the central recess 13 is expelled by the radial channels 132 , thereby generating a lubricant flux in each of the peripheral grooves 124 .

[0072] These features help optimize lubrication and cooling of the cutting tool 10 and the machined part, and thus enable machining of parts made of very hard materials, either ceramic type (such as silicon nitride, zirconium oxide, etc.) or sapphire or other gemstones, or any hard metal.

[0073] The fact that the second end of the peripheral groove 124 is closer to the clamping part 11 than the free end of the cutting tool 10 makes it possible to ensure that during operation of the cutting tool 10 most or all of the active surfaces are lubricated.

[0074] Preferably, each radial channel 132 extends lengthwise in a direction forming an acute angle (eg, 45 degrees) with the longitudinal axis of the body of the cutting tool 10 , the acute angle being oriented towards the free end of the body of the cutting tool 10 .

[0075] In another example, the angle may be a value between 35 degrees and 55 degrees.

[0076] This feature is advantageous because it enables the lubricant to be better distributed around the body of the cutting tool 10 .

[0077] More preferably, the direction along which each radial passage 132 extends lengthwise has a spiral shape. In other words, each passage has a curved shape.

[0078] This feature enables further improved distribution of lubricant around the body of the cutting tool 10 and therefore helps to further limit temperature rise at the interface between the cutting tool 10 and the machined part during machining, which helps prevent premature wear of the electrodeposits.

[0079] The lip 131 has the function of increasing the expulsion pressure of the lubricant at the discharge opening 130 and thus reducing or eliminating lubricant pressure losses in the central hollowing 13 generated by the radial channels 132. The recess 123 for its part has the function of ensuring that the expelled lubricant flux is evenly distributed radially.

[0080] In the present embodiment example of the invention and as particularly in Figure 2 As illustrated in , the insert 20 has an insert 20 body in the form of a blind hollow tube 21 of circular cross section, which is intended to house and form the body of the cutting tool 10 .

[0081] The hollow tube 21 is connected to a central shaft 22 via radial shafts 23 , wherein the radial shafts 23 are intended to form radial channels 132 , and the central shaft 22 is intended to form the central hollowing 13 .

[0082] The insert 20 also comprises an appendage 24 which extends helically on the inner peripheral face of the hollow tube 21 from each radial axis 23 to the inner face of the bottom wall of said hollow tube 21. The appendage 24 is intended to form a peripheral groove 124.

[0083] The central shaft 22 comprises, at one of its ends by means of which it is connected to the bottom wall, a portion of reduced cross-section defining a radial groove 25 intended to form a lip 131 .

[0084] The radial groove 25 is connected to the inner face of the bottom wall by a neck-moulding 26 which is intended to form a recess 123 .

[0085] Finally, appendages 27 extend radially on the inner face of the bottom wall from the neck molding 26 to the inner peripheral face 120 of the hollow tube 21. These appendages 27 are intended to form end grooves 122 when the manufacturing method according to the invention is implemented.

[0086] It is worth noting that the present invention can be applied to a cutting tool and a method of the same, the cutting tool being intended to perform a drilling, milling operation or any other machining operation.

Claims

1. A cutting tool (10), characterized in that: The cutting tool (10) comprises a body, comprising a lubrication orifice and having a clamping portion (11) intended to be fastened to a tool holder chuck and an active portion comprising an active surface, the active surface having essentially a cylindrical shape of revolution, comprising a peripheral surface (120) and an end surface (121), the end surface (121) defining the free end of the body of the cutting tool (10), along which a helical groove extends, the groove being connected via a radial channel (132) to a groove axially extending in the body of the tool. The central hollow portion (13) extends in a straight line, the central hollow portion (13) extending between the lubricant inlet openings opposite to the lubricant discharge opening (130), the central hollow portion (13) having a radial lip (131) at the discharge opening (130), the radial lip being arranged so as to gradually reduce the cross section of the central hollow portion (13), the discharge opening (130) leading to the free end via the recess (123), so that the cross section of the central hollow portion (13) gradually increases from the radial lip (131) to the free end.

2. The cutting tool (10) according to claim 1, characterized in that The peripheral groove (124) extends spirally between: a first end, which leads to the free end of the cutting tool (10); and a second end, which leads to the vicinity of the clamping part (11) of the cutting tool (10), that is, closer to the clamping part (11) than the free end of the cutting tool (10).

3. The cutting tool (10) according to any one of claims 1 to 2, characterized in that: The cutting tool (10) includes an end groove (122) extending radially from the recess (123) to the peripheral surface (120) on the end surface (121).

4. The cutting tool (10) according to any one of claims 1 to 2, characterized in that Each radial channel (132) extends lengthwise in a direction forming an acute angle with the longitudinal axis of the body of the cutting tool (10), the acute angle being oriented toward the free end of the body of the cutting tool (10).

5. The cutting tool (10) according to claim 4, characterized in that The direction along which each radial passage (132) extends lengthwise has a spiral shape.

6. A method for manufacturing a cutting tool (10) having a lubrication opening of complex shape, characterized in that The cutting tool (10) is a cutting tool according to any one of claims 1 to 5, and the method comprises the following steps: - producing an insert (20) made of plasticized polyvinyl butyral, plasticized cellulose acetate butyrate or polybutyl methacrylate acrylic resin, - overmolding the body of the cutting tool (10) by means of the insert (20) made of a polymer by injection into a mould, - removing the insert (20) made of polymer in order to form a lubrication orifice in the body of the cutting tool (10), the shape of the lubrication orifice being complementary to the shape of a portion of the insert (20), - sintering the body of the cutting tool (10), - machining the body of the cutting tool (10) on at least one portion, called "active portion", - depositing an abrasive coating on the surface of the active part of the body of the cutting tool (10).

7. The method according to claim 6, characterized in that The step of removing the insert (20) is performed by introducing the insert (20) into a bath.

8. The method according to any one of claims 6 to 7, characterized in that The insert (20) is produced by an additive manufacturing method.

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