Tool for machining machine in particular for hybrid three-dimensional printer with tool change

Abstract

The invention relates to a milling / drilling / tapping head (100) for a part manufacturing machine, for example of the milling machine, machining center or three-dimensional printer type with tool change, comprising at least one rotary brushless motor (103) provided with a shaft (104) rotating at a high speed greater than or equal to 50,000 rpm, a milling tool coupling chuck (105, 107) engaged on said shaft (104), an external main body (101) forming a solid block enclosing at least said motor (103) in the manner of a sheath (102), said device further comprising an integrated heat fluid cooling system (110) incorporated inside the external main body (101) and comprising at least one cold fluid inlet orifice (111), a heated fluid outlet orifice (112) and a pipe (113) circulating the heat fluid around the motor (103), from the inlet orifice (111) to the outlet orifice (112).Figure for abstract: Fig. 9.

Description

Title of the invention: Tool for a machining machine, in particular for a hybrid three-dimensional printer with tool change Technical field of the invention

[0001] The present invention relates to a machining tool such as a milling / drilling / tapping head for a machining machine, and in particular for a hybrid three-dimensional printer with tool change. Prior art

[0002] Material removal machining technologies, in particular milling, turning, or drilling / tapping, use tools (solid or insert cutters, drills, taps) which can rotate at high speeds and / or move with a high feed rate relative to the part to be machined, the cutting carried out by the tool causes significant heating of the tool and of the material constituting said part.

[0003] To solve this problem, there are many lubrication and cooling systems using what is commonly called cutting oil sprayed in the form of jets or mist using a pumping circuit and adjustable nozzles. Some advanced solutions even use oil injection directly into the tool, particularly in a sprayed form.

[0004] However, even though these technologies have been proven for decades, they remain limited to general application areas.

[0005] Indeed, in the specific context of a three-dimensional plastic printing machine with tool change which would use both additive manufacturing and subtractive manufacturing, all in a closed enclosure subjected to a temperature exceeding 150°C to 200°C, none of the solutions existing to date could be adapted / transposed.

[0006] Indeed, during additive manufacturing phases, the three-dimensional printing heads are brought to a high temperature, as is the plate (bed) on which the molten material is deposited. Thus, within the enclosure of such a machine, the temperature can exceed 150 to 200°C because it is necessary for the hard material to reach its glass transition temperature in order to melt and exit the printing nozzle. However, in the event that the three-dimensional printing head had to be replaced by a drilling or milling head of a known type, it seems obvious that a cutting oil jet / spray system would absolutely not be compatible with such a machine because there would be oil projections everywhere, which is absolutely not desired and would completely harm the manufacturing and integrity of the part. Furthermore, the lubrication devices used and described above are used to lubricate and cool the part and the tool at their contact surface, i.e. at the point where machining is carried out by material removal. Typically, in the case of milling or drilling, machining oil jets are used to facilitate the penetration of the cutter or drill into the material while evacuating the heat produced during this contact at high speed (rotation / feed). They are also used for fragmentation and evacuation of chips outside the machining area but in a very random and difficult to control form, again totally incompatible with the problem to be solved.

[0007] However, not only are the current lubrication and cooling devices used in subtractive manufacturing not adapted to the context, but the motors which operate these machining tools would themselves be subjected to the high temperatures prevailing inside the enclosure of the three-dimensional printer, which would require their rotation speed to be significantly reduced, making them lose all usefulness, or potentially damaging them irreparably or destroying them, which is obviously not desired.

[0008] It is in this context that the present invention proposes to solve the problem of cooling a subtractive manufacturing tool, such as a milling cutter or a drill, in a three-dimensional printer with tool change, the working enclosure of which is almost permanently subjected to high temperatures exceeding 150 to 200°C. Presentation of the invention

[0009] The present invention aims to remedy these drawbacks with a completely innovative approach.

[0010] To this end, according to a first aspect, the present invention relates to a milling / drilling head for a part manufacturing machine, for example of the milling machine, machining center or three-dimensional printer type with tool change, comprising at least: - a rotary brushless motor with a shaft rotating at a high speed greater than or equal to 50,000 rpm, - a milling tool coupling chuck engaged on said shaft, - an external main body forming a solid block enclosing at least said motor in the manner of a sheath, - said device further comprising an integrated heat fluid cooling system incorporated inside the external main body and comprising at least one cold fluid inlet, one heated fluid outlet and a pipe circulating the heat fluid around the rotary engine, from the inlet to the outlet.

[0011] This solution thus makes it possible to use subtractive manufacturing tool motors with a high rotation rate in a high temperature environment, without any impact on the quality of the machining, its speed, its precision or the potential deterioration / destruction of the motor.

[0012] In addition, the body is sized to take up as little volume as possible while ensuring the storage and gripping functions of the tool.

[0013] Finally, making a solid part as the motor sheath makes it possible to reduce the natural vibration modes and to stiffen the tool.

[0014] The invention is implemented according to the embodiments and variants set out below, which are to be considered individually or in any technically effective combination.

[0015] Advantageously, the cooling system comprises at least one pipe arranged as close as possible to the engine.

[0016] Preferably, the cooling system comprises at least one “U”-shaped pipe arranged close to the shaft and substantially perpendicular to the latter.

[0017] According to an alternative embodiment, the cooling system comprises at least one sinusoidal pipe arranged substantially all around the engine in the form of meanders.

[0018] According to an alternative, the cooling system comprises at least one helical pipe wound substantially all around the engine, forming turns.

[0019] According to another variant, the cooling system comprises a main inlet pipe separating into several secondary pipes extending parallel to each other substantially all around the engine and joining into a common outlet pipe.

[0020] These last three solutions make it possible to distribute the cooling as well as possible not only all around the motor but also over the largest dimension of the latter so that it retains its technical characteristics and the tool itself does not overheat.

[0021] Preferably, the head further comprises a chip suction system fixed under the external main body and comprising at least one suction duct leading as close as possible to the milling tool.

[0022] This solution makes it possible to avoid, as in the machine tools of the prior art, having to use cutting oil to remove the chips.

[0023] According to a preferred embodiment of the present invention, the head also comprises a tool offset determination system comprising at least one carbon brush held in contact with the coupling mandrel using a side plate.

[0024] This solution allows the tool to be better positioned and thus increases machining precision.

[0025] According to a particular embodiment of the present invention, the cooling system further comprises connectors connected respectively to the fluid inlet orifice and to the fluid outlet orifice, external means for pumping heat fluid and hoses connecting the external pumping means to the connectors in order to circulate said fluid.

[0026] According to a particularly interesting aspect of the present invention, the heat fluid is chosen from glycol, oil, argon, or supercritical CO2.

[0027] Advantageously, the head also comprises a coupling member for an external removable tool coupling device.

[0028] The present invention also relates to a part manufacturing machine, for example by subtractive manufacturing such as a milling machine or a machining center, or by additive manufacturing such as a three-dimensional printer with tool change, comprising a chassis, a support for the part to be manufactured, a movable plate and a milling / drilling head as described previously. Brief description of the figures

[0029] Other advantages, aims and characteristics of the present invention emerge from the following description given, for explanatory and in no way limiting purposes, with reference to the appended drawings, in which:

[0030] [Fig-1] [Fig.l] is a perspective view of a three-dimensional printing machine tool changing system using a milling / drilling / tapping head according to the present invention,

[0031] [Fig.2] [Fig.2] is a side view of [Fig.l],

[0032] [Fig.3] [Fig.3] is an exploded perspective view of the head of Figures 1 and 2,

[0033] [Fig.4] [Fig.4] is a front view of [Fig.3],

[0034] [Fig.5] [Fig.5] is a back view of [Fig.3],

[0035] [Fig.6] [Fig.6] is a top view of [Fig.3],

[0036] [Fig.7] [Fig.7] is a bottom view of [Fig.3],

[0037] [Fig.8] [Fig.8] is a side view of [Fig.3],

[0038] [Fig.9] [Fig.9] is a view along section AA of [Fig.8],

[0039] [Fig. 10] [Fig. 10] is a view along section BB of [Fig.8],

[0040] [Fig. 11] [Fig. 11] is a perspective view in transparency of a variant of the rea reading of the head of figures 3 to 10,

[0041] [Fig. 12] [Fig. 12] is a perspective view in transparency of another alternative embodiment of the head of figures 3 to 10, and

[0042] [Fig. 13] [Fig. 13] is a perspective view in transparency of another variant of realization of the head of figures 3 to 10. Description of the embodiments

[0043] Figures 1 and 2 schematically represent a three-dimensional printing machine 10 with tool change, also called an additive manufacturing machine (Fused Deposit Material or Fused Filament Fabrication), equipped in this case with at least one machining tool 100 in accordance with the present invention and presented in more detail in Figures 3 and following.

[0044] The present description is given without limitation, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment.

[0045] It should be noted, from now on, that the figures are not necessarily to scale, without this hindering their understanding.

[0046] The three-dimensional printing machine 10 according to the present invention typically comprises an enclosure 11 (preferably at least partly transparent) which can be closed for the manufacture of a part and opened to recover it, a plate 12 (also called a "bed"), most often heated to a high temperature (150-200°C), on which the part being manufactured rests, and a support 13 of the rail or rack type on which various tools 100 are stored, for example a three-dimensional printing head by wire deposition, or, as described below in relation to FIGS. 3 to 13, a milling head 100 mounted on a support 50 of the carriage type, movable along perpendicular rails 30 and 40 in two directions X and Y of an orthonormal reference frame. The plate 12 is itself movable vertically in a linear manner from top to bottom and from bottom to top along a rail 60 in a direction Z perpendicular to the directions X and Y.The carriage 50 and the plate 12 are moved independently using a known type of motorization system (stepper motor and toothed belt mounted on pulleys for example) to carry out the movements along the respective rails 30, 40 and 60.

[0047] Figures 3 to 10 show in more detail using various views the machining tool 100 which is the subject of the present invention, namely a milling head in this case.

[0048] In the context of the present invention, the three-dimensional printing machine 10 is of the hybrid type and uses, in a manner known per se, a spool of plastic wire in the hardened state such as PLA (polylactic acid) or PEEK (Polyetheretherketone). However, many other plastic or metal materials may be involved.

[0049] The milling head 100 comprises an external main body 101 forming a solid block, for example made of aluminum, provided with a preferably cylindrical bore 102 forming a receiving sheath for a small-sized, brushless-type electric motor 103.

[0050] This motor 103 is provided at a lower end with a drive shaft 104 capable of rotating at speeds exceeding 50,000 rpm, for example 55,000 rpm.

[0051] A removable coupling chuck 105 is tightly mounted around the drive shaft 104 and carries a milling cutter 106 of known type fixed by an ER collet 107 of known type.

[0052] An upper plate 108 fixed to the top of the main body 101 makes it possible to centralize a set of connectors and hoses linking the milling tool 100 to the machine 10 via the carriage 50.

[0053] The motor 103 is controlled in rotation rate and direction of rotation by two electronic cards in series (not shown) which make it possible to interface the motor 103 with a programmable control card integrated into the machine and storing different machining programs.

[0054] The machining head 100 further comprises an integrated cooling system 110 (see [Fig.9]) comprising an inlet 111 for heat-transfer fluid, for example glycol, an outlet 112 for heated fluid and a pipe 113 transporting the fluid from the inlet 111 to the outlet 112. This pipe 113 is preferably positioned as close as possible to the motor 103 in order to cool it as efficiently and quickly as possible, mainly during its use. The fluid inlet 111 is provided with a connector 111a of known type and the fluid outlet 112 is also provided with a similar connector 112a, each of these connectors being respectively connected via a hose 111b and 112b to a heat-transfer fluid injection system such as a pump (not shown).

[0055] In the example of figures 3 to 10, this pipe 113 comprises a channel 113a connected to the inlet 111, a central channel 113b in the shape of a “U” surrounding the motor 103, preferably close to the drive shaft 104, and an outlet channel 113c connected to the outlet 112.

[0056] The machining head 100 also comprises a chip suction system 200 fixed under the external main body 101 and comprising at least one suction conduit 201 ending as close as possible to the milling tool 106. The channel 201 is typically connected to a suction system not shown.

[0057] The machining head 100 further comprises a determination system 300 for locating by probing a potential tool offset 106, this system 300 comprising for this purpose at least one electrically conductive carbon brush 301 placed in a tube 302 and held in contact with the coupling mandrel 105 using a side plate 303.

[0058] The machining head 100 finally comprises a member 400 for coupling to a removable tool coupling device 55 integrated into the carriage 50 and making it possible to take the tool 100 from the rack 13, couple it to said coupling member device 400 to use it in the machining phase, and place it back on its rack 13, in particular to replace it with another subtractive manufacturing tool (drilling or tapping head), with an additive manufacturing tool (three-dimensional printing head) or with other tools (probing, marking, finishing).

[0059] According to an alternative embodiment shown in [Fig.l 1], the cooling system 110 comprises at least one sinusoidal pipe 123 arranged substantially all around the motor 103, forming upper and lower meanders 124 between an inlet pipe 123a and an outlet pipe 123c. This solution makes it possible to better distribute the heat transfer fluid around the motor 103 and over a significant portion of its height, which improves its cooling, all in a reduced footprint.

[0060] According to an alternative shown in [Fig. 12], the cooling system 110 comprises at least one helical pipe 133 wound substantially all around the engine 103, forming turns 134 between an inlet pipe 133a placed in the upper position in the present case and an outlet pipe 133c. This solution allows circulation of the heat-transfer fluid in a single direction (a priori from bottom to top) but with an optimized flow over the part of the height of the engine subject to cooling.

[0061] According to another embodiment, shown in [Fig. 13], the cooling system 110 comprises a main inlet pipe 143a placed in the upper position in the present case separating into several independent secondary pipes 143 extending parallel to each other substantially all around the engine 103 and joining in a common outlet pipe 143c placed in the upper position. This solution again allows a very good distribution of the heat transfer fluid with preferably a circulation from bottom to top to simultaneously cool the entire circumference of the engine from the hottest part to the coldest part.

[0062] The body 101 has been dimensioned so as to take up the least possible volume but ensuring the functionalities of storing the tool 100, gripping the tool 100, moving the tool 100, transporting the motor 103, liquid cooling the motor 103 and supporting the systems 200 and 300 respectively for suction and determining tool offset. In addition, producing a massive part like this makes it possible to reduce the natural vibration modes and to stiffen the tool 100.

[0063] The operation of the hybrid machine 10 for additive and subtractive manufacturing of parts in accordance with the present invention is as follows.

[0064] The use of the milling head 100 may occur during a subtractive manufacturing phase subsequent to an initial additive manufacturing phase of at least a portion of the part to be produced, using for this purpose a three-dimensional printing head not forming the subject of the present invention. The milling head 100 therefore operates in the present case within a particularly hot closed environment (150-200°C) resulting from the three-dimensional printing (heating of the material at the level of the printing head and heating of the plate 12).

[0065] Once the milling head 100 is connected to the coupling device 55 of the mobile transport carriage 50, control commands are sent to the milling head 100 by a program already recorded in the electronic card of the machine 10.

[0066] The machining head 100 placed on its carriage 50 is moved along the rails 30 and 40 and in the space of the enclosure 11 of the machine 10 in the X and Y directions, preferably following a zero point taking procedure (homing) thanks to the system 300 for determining the tool offset 106 in order to carry out the machining operations at the correct coordinates. The plate 12 can also move vertically along its rail 60. The motor 103 is then started until its drive shaft 104 reaches the rotation speed programmed in the range possible by the motor between 5,000 rpm and 50,000 rpm, while the respective cooling systems 110 and chip suction 200 are started.

[0067] The milling tool 106 then machines the (portion of) part placed on the plate 12 according to the chosen program (path of the milling tool 106, rotation speed of the shaft 104, relative speed of movement of the machining head 100 with respect to the part by coordinated movements of the carriage 50 and / or the plate 12). Throughout the machining phase, the heat transfer fluid circulates in the pipes 113, 123 or 143 of the cooling system 110 provided for this purpose, with a flow rate adapted to cool the motor 103 in an optimized manner (for example 6000 cmVmin). In parallel, the suction system 200 evacuates the chips from the machining zone so as not to harm the manufacture of the part being produced.

[0068] Once this machining phase is completed, the milling head 100 can be placed back on the rack 13 using the carriage 50 and the removable coupling member 400 which disconnects from the coupling device 55.

[0069] A new machining phase can then begin if necessary. For this, the program of the machine 10 tells the carriage 50 to fetch a new tool from the rack 13 to launch, for example, a drilling or tapping phase with a new machining head equipped with a drill or a tap, or a polishing phase with a new specific tool, or an additive manufacturing phase using a three-dimensional printing head or a three-dimensional measurement phase (verification of the dimensions and / or surface conditions) with, for example, a tool feeler.

[0070] An important advantage of the present invention lies in the use of a compact brushless motor 103 capable of reaching high rotation speeds, typically more than 50,000 rpm, making it possible to machine many types of materials (plastics, metals, alloys), equipped with a cooling system 110 making it possible to keep the motor 103 at a controlled temperature at which its operation is little impacted.

[0071] Furthermore, the general principle of the assisted manufacturing program consists of an interleaving of printing and machining phases correlated with the tool trajectories used for each of these phases. Depending on the version of the program and the machine concerned, the interleavings are managed automatically or their positions are requested from the user. The printing code is cut by the layer changes, the machining phases of the just printed layer being introduced during these changes. The output file of the module is a code readable by the most widespread numerically controlled machine controllers.

[0072] It must of course be considered that the detailed description of the subject of the invention, given solely by way of illustration, does not constitute in any way a limitation, the technical equivalents also being included in the scope of the present invention.

[0073] Thus, the milling head can be replaced by a drilling / tapping head equipped with a drill bit or a tap.

[0074] The glycol can be replaced by a gas such as argon, or liquid nitrogen or supercritical CO2.

Claims

Claims

1. Milling / drilling / tapping head (100) for a three-dimensional printer (10) with tool change, comprising at least: - a rotary brushless motor (103) provided with a shaft (104) rotating at a speed of between approximately 5,000 and 50,000 rpm, - a milling tool coupling chuck (105, 107) engaged on said shaft (104), - an external main body (101) forming a solid block enclosing at least said motor (103) in the manner of a sheath (102), - said device further comprising an integrated heat-fluid cooling system (110) incorporated inside the external main body (101) and comprising at least one cold fluid inlet orifice (111), a heated fluid outlet orifice (112) and a pipe (113; 123; 133;143) circulating the heat fluid around the motor (103), from the inlet orifice (111) to the outlet orifice (112), and - a chip suction system (200) fixed under the external main body and comprising at least one suction duct leading as close as possible to the milling tool.;

2. Milling / drilling / tapping head (100) according to claim 1, characterized in that the cooling system (110) comprises at least one pipe (113; 123; 133; 143) arranged as close as possible to the motor.

3. Milling / drilling / tapping head (100) according to claim 2, characterized in that the cooling system (110) comprises at least one U-shaped pipe (113a, 113b, 113c) arranged close to the shaft (104) and substantially perpendicular to the latter.

4. Milling / drilling / tapping head (100) according to claim 2, characterized in that the cooling system (110) comprises at least one sinusoidal pipe (123) arranged substantially all around the motor (103) forming meanders (124).

5. Milling / drilling / tapping head (100) according to claim 2, characterized in that the cooling system (110) comprises at least one helical pipe (133) wound substantially all around the motor (103) forming turns (134).

6. Milling / drilling / tapping head (100) according to claim 2, characterized in that the cooling system (110) comprises a main inlet pipe (143a) separating into several secondary pipes (143b) extending parallel to each other substantially all around the engine (103) and joining into a common outlet pipe (143c).

7. Milling / drilling / tapping head (100) according to any one of the preceding claims, characterized in that it also comprises a tool offset determination system (300) comprising at least one carbon bar (301) slid into a tube (302) and held in contact with the coupling mandrel (105) using a side plate (303).

8. Milling / drilling / tapping head (100) according to any one of the preceding claims, characterized in that the cooling system (110) further comprises connectors (11a, 111b) connected respectively to the fluid inlet orifice (111) and to the fluid outlet orifice (112), external means for pumping heat-transfer fluid and hoses connecting the external pumping means to the connectors (111a, 111b) in order to circulate said fluid.

9. Milling / drilling / tapping head (100) according to any one of the preceding claims, characterized in that the heat fluid is chosen from glycol, oil, argon, liquid nitrogen or supercritical CO2.

10. Milling / drilling / tapping head (100) according to any one of the preceding claims, characterized in that it further comprises a member (400) for coupling to an external removable tool coupling device of a transport carriage (50).

11. A three-dimensional tool-changing printer, comprising a frame (11), a heated workpiece support (12) and a milling / drilling / tapping head (100) according to any one of the preceding claims.

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