JP7687871B2 - METAL SHAPE MANUFACTURING METHOD AND METAL SHAPE MANUFACTURING APPARATUS - Google Patents

Description

The present invention relates to a method for manufacturing a metal object and an apparatus for manufacturing a metal object.

Conventionally, a known device configuration for WAAM (wire arc additive manufacturing) is one that uses an arc welding robot to layer metal.

When WAAM is used to mold an object, heat input from arc welding causes heat to accumulate in the object, and as the molding progresses, the bead width increases, making it difficult to mold an object with a uniform width. To solve this problem, it is known to use a cooling device to cool the object while it is being stacked and molded (see Patent Document 1).

JP 2017-144446 A

However, the inventors' investigations revealed that the method described in Patent Document 1 had a problem in that, especially shortly after the start of modeling, large irregularities formed on the surface of the model as a result of the metal being layered.

Therefore, the present invention has been made in consideration of the above circumstances, and provides a manufacturing method and a manufacturing device for a metal object that can prevent large irregularities from being formed on the surface of the metal object as a result of the metal being layered.

In order to achieve the above object, the present invention employs the following means.
In other words, the manufacturing method of a metal object according to the present invention is a manufacturing method of a metal object in which a metal object is formed on a base material, and includes a base material installation step of installing the base material in contact with a temperature adjustment unit, and a metal lamination step of laminating a molten metal material on the base material to form the metal object, in which the base material is heated by the temperature adjustment unit, a heating step of pre-warming the base material, and then laminating the molten metal material on the base material, and a cooling step of cooling the base material so that the base material does not become too hot due to the heat input of the molten metal material, thereby forming the metal object on the base material within a range of required dimensional accuracy , and in the base material installation step, a fixed jig that is annular and arranged along the outer edge of the base material is installed on the upper side of the base material, and the base material is sandwiched between the temperature adjustment unit and the fixed jig .

In the conventional method for manufacturing a metal object, the layer formed on the base material with molten metal to form the metal object, and the layer formed on the base material (base layer) in sequence with molten metal to form the metal object, are heat-dissipated to the base material and immediately solidified. For this reason, the newly laminated layer is difficult to blend with the base layer, and large irregularities are likely to be formed on the surface of the metal object. However, in the method for manufacturing a metal object according to the present invention, the base material is heated by a temperature adjustment unit. As a result, the amount of heat dissipated to the base material is reduced for the layer formed on the base material with molten metal to form the metal object, and the layer formed on the base material (base layer) in sequence with molten metal to form the metal object. As a result, the newly laminated layer is easily blended with the base layer, and it is possible to suppress the formation of large irregularities on the surface of the metal object as traces of metal lamination.
In the method for producing a metal object configured as described above, the base material is heated by the temperature adjustment unit in the metal lamination step, and then cooled. Heating the base material in this manner suppresses problems that occur soon after lamination begins, such as large irregularities formed on the surface of the metal object and narrow bead widths. Meanwhile, in the metal lamination step, the base material is heated by the temperature adjustment unit, and then cooled, suppressing problems that occur as the metal object is formed, such as heat being accumulated due to heat input from arc welding or the like, causing the temperature to rise and the bead width to increase. Therefore, in the method for producing a metal object according to this embodiment, a constant bead width can be obtained regardless of the timing of forming the metal object.

According to another aspect of the present invention, there is provided an apparatus for manufacturing a metal object, the apparatus comprising: a modeling device that stacks molten metal material to form a metal object; a temperature adjustment unit that has a heating device that comes into contact with a base material on which metal is stacked by the modeling device and generates heat when the metal object is being formed by the modeling device, and a cooling device that absorbs ambient heat; and a control unit that is capable of setting a heating mode in which the heating device is operated before forming the metal object in the base material, and a cooling mode in which the cooling device is operated after the heating mode is stopped, wherein the control unit starts forming the metal object by stacking the molten metal material on the base material in the heating mode, and switches to the cooling mode after the heating mode is stopped to cool the base material so that the temperature of the base material does not increase due to the heat input of the molten metal material, and forms the metal object in the base material within a range of required dimensional accuracy, the base material being annular and sandwiched between a fixing jig that is installed on the upper side of the base material along an outer edge of the base material, and the temperature adjustment unit .

Furthermore, in the metal object manufacturing device according to the present invention, the base material is heated by the temperature adjustment unit. As a result, in addition to the layer formed directly on the base material with molten metal to form the metal object, the amount of heat dissipated to the base material is reduced in the layers formed with molten metal to form the metal object, which are successively formed on the layer (base layer) formed on the base material. As a result, the newly laminated layer blends easily with the base layer, making it possible to prevent large irregularities from being formed on the surface of the metal object as traces of the laminated metal.

The method and device for manufacturing a metal object according to the present invention can prevent large irregularities from forming on the surface of the metal object due to the metal being laminated.

1 is a diagram showing a schematic diagram of a manufacturing apparatus for a metal object according to an embodiment of the present invention; FIG. 2 is a diagram showing a temperature adjustment unit of the metal object manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a flow diagram showing a method for producing a metal object according to an embodiment of the present invention.

An apparatus for manufacturing a metal object according to an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a diagram illustrating a metal object manufacturing apparatus according to an embodiment of the present invention, which includes a positioner (support table) 10, a temperature control plate (temperature adjustment unit) 20, a fixing jig 26, and a modeling robot (modeling device) 3.

The positioner 10 is capable of supporting a metal object, which will be described later. The positioner 10 is installed, for example, on a floor surface. The positioner 10 has a rotating table 11. The upper surface 11u of the rotating table 11 is flat along a horizontal plane. The rotating table 11 is capable of rotating around an axis that has a predetermined direction (for example, the vertical direction) as its axial direction. Note that a non-rotating table may be used as the support table instead of the positioner 10.

The temperature control plate (temperature adjustment unit) 20 is installed on the upper surface 11u of the rotating table 11 of the positioner 10. The temperature control plate 20 may be fixed to the rotating table 11 of the positioner 10 by a fixing device (not shown).

Figure 2 is a diagram showing the temperature control plate 20. In Figure 2, the case 21 is indicated by a two-dot chain line. As shown in Figure 2, the temperature control plate 20 has a case 21, a cooling pipe (cooling device) 22, and a heating section (heating device) 23.

The case 21 has a generally rectangular parallelepiped shape. A space is formed inside the case 21. The temperature control plate 20 may incorporate a thermometer (not shown) for temperature control. Alternatively, a radiation thermometer for measuring the surface temperature of the metal object W, which will be described later, may be provided separately.

The cooling pipe 22 is inserted through an insertion hole (not shown) formed in the case 21 and is arranged in a serpentine manner inside the case 21. The cooling pipe 22 is tubular. By flowing (operating) cooling water inside the cooling pipe 22, the flowing cooling water absorbs the surrounding heat and cools the surroundings.

The heating unit 23 is, for example, a cartridge heater, and generates heat by passing electricity through the heater (operating), thereby warming the surroundings. The heating unit 23 and the cooling pipe 22 are inserted through an insertion hole (not shown) formed in the case 21, and are disposed inside the case 21.

The temperature control plate 20 can be selectively set by a control unit (not shown) to a cooling mode in which cooling water is circulated through the cooling pipe 22, and a heating mode in which the heating unit 23 is heated.

The temperature control plate 20 is installed on the upper surface 11u of the positioner 10. The case 21 has a mounting hole (not shown) that penetrates in the vertical direction at a position that does not interfere with the cooling pipe 22 and the heating section 23.

As shown in FIG. 1, the base material B, which will be described later, can be placed on the upper surface 21u of the case 21. In other words, the temperature control plate 20 can come into contact with the base material B. In this embodiment, the base material B is made of a metal that has a rectangular shape when viewed vertically from above. Note that the shape of the base material B when viewed vertically from above is not limited to a rectangular shape, and may be a circular shape. In a plan view, the base material B is smaller than the temperature control plate 20. Mounting holes (not shown) that penetrate in the vertical direction are formed in the four corners of the base material B.

The fixing jig 26 is installed on the upper surface Bu of the base material B. In a plan view, the fixing jig 26 has a rectangular ring shape. The fixing jig 26 is arranged along the outer edge of the base material B. Mounting holes (not shown) that penetrate in the vertical direction are formed in the four corners of the fixing jig 26.

A fastener 28 such as a bolt is inserted through the mounting hole of the fastener 26 and the mounting hole of the base material B, and is fastened to the mounting hole of the temperature control plate 20. The fastener 26 is fixed to the temperature control plate 20 together with the base material B by the fastener 28. Note that although a bolt is used as the fastener 28 in this embodiment, a clamp or the like may also be used. When a clamp is used as the fastener 28, the fastener 26 can be fixed to the temperature control plate 20 together with the base material B without providing mounting holes in the fastener 26 and the base material B.

The modeling robot 3 has a robot arm 30 and a welding torch 31. The modeling robot 3 is a 3D printer (WAAM) that uses arc welding and is a well-known configuration.

The robot arm 30 extends from a robot body (not shown). A welding torch 31 is provided at the tip of the robot arm 30. A welding wire 32 is supplied to the welding torch 31 from a wire supply device (not shown). An arc discharge is generated at the tip of the welding wire 32 to melt the welding wire 32, and the welding wire 32 is layered on the base material B to produce a metal object W. In this embodiment, the metal object W is cylindrical, but the shape can be set as appropriate.

Next, a method for producing a metal shaped article will be described.
3 is a flow diagram showing a method for producing a metal shaped product. As shown in FIG 3, a base material setting step S1 is carried out.
The temperature control plate 20 is placed on the upper surface 11u of the support stand 10. The base material B is placed on the upper surface 21u of the temperature control plate 20. A fixing jig 26 is placed on the upper surface Bu of the base material B. A fixing jig 28 such as a bolt is inserted through the mounting holes of the fixing jig 26 and the mounting holes of the base material B, and fastened to the mounting holes of the temperature control plate 20.

Next, a metal lamination step S2 is performed.
Using the modeling robot 3, metal (metal material) is laminated on the upper surface Bu of the base material B to form a metal object W. Before laminating and forming the metal object W, the temperature control plate 20 is set to a heating mode to preheat the base material B (upper surface Bu) (heating step). This makes it possible to prevent large irregularities from being formed on the surface of the metal object W as traces of the laminated metal.
After preheating the base material B, the modeling robot 3 uses a welding torch 31 to deposit metal melted by arc discharge from a welding wire 32 on the upper surface Bu of the base material B, thereby forming a metal model W.
Heating of the base material B by the temperature control plate 20 is stopped after the formation of the metal object W on the upper surface Bu of the base material B begins, when the effect of the temperature of the base material B, more specifically, the effect of heat radiation to the base material B, becomes small.
Then, in the metal lamination step S2, as the formation of the metal object W starts, the influence of heat radiation to the base material B decreases, while the influence caused by the heat melting the welding wire 32 being stored in the metal object W being formed increases. Therefore, in the metal lamination step S2, after the heating mode of the temperature control plate 20 is stopped, the temperature control plate 20 is switched to the cooling mode to cool the base material B (upper surface Bu) (cooling step). This prevents the bead width from increasing as the metal object W is formed, and keeps the bead width constant regardless of the timing of forming the metal object W.

Next, the fixing device 28 is removed, and the metal object W integrated with the base material B is removed from the temperature control plate 20. The temperature control plate 20 can be reused when molding the next metal object.

According to the metal object manufacturing device 1 and the metal object manufacturing method configured in this manner, in the metal lamination step S2, before the metal object W is formed on the base material B, the base material B is preheated by the temperature control plate 20. As a result, in addition to the layer formed directly on the base material B with molten metal to form the metal object W, the amount of heat dissipated to the base material B is reduced in the layers formed with molten metal to form the metal object W on the layer (base layer) formed on the base material B in sequence. As a result, the newly laminated layer is more easily compatible with the base layer, and it is possible to prevent large irregularities from being formed on the surface of the metal object W as a trace of the metal lamination.

In addition, usually, the upper side of the metal molded object W accumulates heat due to heat input from arc welding, etc., and becomes hot, resulting in a large bead width, while the lower side is dissipated to the base material B and solidifies immediately, resulting in a small bead width. In the manufacturing method of the metal molded object of this embodiment, in the metal lamination step S2, the base material B is heated by the temperature control plate 20 and then cooled. By heating the base material B in this manner, problems such as large irregularities formed on the surface of the metal molded object W and narrow bead widths, which occur shortly after lamination begins, are suppressed. On the other hand, in the metal lamination step S2, the base material B is heated by the temperature control plate 20 and then cooled, thereby suppressing problems such as heat accumulation due to heat input from arc welding, etc., and becoming hot as the metal molded object W is formed, resulting in a large bead width. Therefore, in the manufacturing method of the metal molded object of this embodiment, a constant bead width can be obtained regardless of the timing of forming the metal molded object W.

In addition, with the base material B sandwiched between the fixing jig 26 and the temperature control plate 20, the fixing jig 26 is fixed to the temperature control plate 20 by the fixing jig 28. Here, the metal object W is formed by partially melting the base material B with heat and bonding it to the base material B, so that the base material B goes from a melted and expanded state to a contracted state as it cools and hardens, causing warping of the base material B (so-called welding distortion). However, because the base material B is sandwiched between the fixing jig 26 and the temperature control plate 20, warping of the base material B is suppressed.

In addition, a thermometer is built into the temperature control plate 20, allowing the temperature of the metal object W to be controlled, making it possible to create an object of uniform width or width with the required dimensional accuracy.

In addition, since the lamination can always start at the same temperature, the variation in the metal object W can be reduced compared to starting at room temperature.

In addition, since there is no need to control the position of the cooling device itself to match the shape of the metal object W, it is easy to control.

The assembly procedures and the shapes and combinations of the components shown in the above-mentioned embodiments are merely examples, and may be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention.

Reference Signs List 1: Metal object manufacturing device 3: Modeling robot 10: Positioner (support stand)
26... Fixing jig 28... Fixing jig B... Base material S1... Base material installation step S2... Metal lamination step W... Metal molded object

Claims (2)

A method for manufacturing a metal object by forming a metal object on a base material, comprising the steps of:
a base material installation step of installing the base material in a state where the base material is in contact with a temperature adjustment unit;
a metal lamination process of laminating a molten metal material on the base material to form the metal object,
In the metal lamination step, the base material is heated by the temperature adjustment unit, a heating step is performed to pre-warm the base material, the molten metal material is laminated on the base material, and the base material is cooled in a cooling step to prevent the base material from becoming too hot due to the heat input of the molten metal material, thereby forming the metal object on the base material within a required range of dimensional accuracy.
In the base material installation process, a fixed jig that is annular and arranged along the outer edge of the base material is installed on the upper side of the base material, and the base material is sandwiched between the temperature adjustment unit and the fixed jig . a molding device that layers molten metal material to form a metal object;
a temperature adjustment unit that comes into contact with a base material on which metal is deposited by the modeling device and that generates heat and a cooling device that absorbs heat from the surroundings when the metal object is being formed by the modeling device;
a control unit that can be set to a heating mode in which the heating device is operated before the metal object is formed on the base material, and a cooling mode in which the cooling device is operated after the heating mode is stopped,
The control unit is
In the heating mode, the molten metal material is laminated on the base material to start forming the metal object.
After the heating mode is stopped,
switching to the cooling mode, cooling the base material so that the base material does not become too hot due to the heat input of the molten metal material, and forming the metal shape in the base material within a required range of dimensional accuracy ;
The base material has an annular shape and is sandwiched between a fixing jig that is installed on the upper side of the base material along the outer edge of the base material and the temperature adjustment unit .

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