JP7491507B2 - Layered manufacturing method and layered manufacturing device - Google Patents

Description

This disclosure relates to an additive manufacturing method and an additive manufacturing device that repeatedly stacks and processes metal plate material one or more layers at a time to create a desired laminated structure.

Patent Literature 1 discloses an additive manufacturing method and an additive manufacturing device that form a layered structure having a desired overall shape by repeatedly performing a step of stacking metal plate materials using friction stir welding (hereinafter abbreviated as "FSW") technology and a step of processing the stacked metal plate materials into a desired cross-sectional shape.
In order to automate this prior art, a supplying device that places the raw metal plate material on the laminated joint and a fixing mechanism for the laminated structure against the processing forces generated during FSW and cutting are required. Well-known raw material supplying devices include robot arm conveying devices and sheet feeders used for conveying sheet metal. Well-known fixing mechanisms for the laminated structure include various clamping devices using hydraulic or pneumatic pressure.

Japanese Patent No. 6587028

However, a typical conveying device has a control mechanism independent of the control mechanism of the additive manufacturing device such as a machining center, and in order to automate it, an interface to control the conveying device is required, which makes it expensive.In addition, a movable range for the conveying device and a space for storing metal sheets are required, which increases the installation area of the machine.
On the other hand, clamping devices are generally designed for the purpose of firmly clamping parts of a desired size, so in additive manufacturing where the height increases, there is an issue that the height of the workpiece that can be clamped is limited by the stroke range of the clamping device.

Therefore, an object of the present disclosure is to provide an additive manufacturing method and an additive manufacturing device that can automate the transportation and arrangement of metal plate materials with a relatively inexpensive and space-saving configuration.
Another object of the present disclosure is to provide an additive manufacturing method and an additive manufacturing device that can also accommodate an increase in the height of a metal plate material due to additive manufacturing.

In order to achieve the above object, a first invention includes a first step of transporting a metal plate material stocked at a predetermined stock position to a predetermined processing position and stacking it on a workpiece;
a second step of joining the metal plate material transported in the first step to the workpiece to form a laminated joint body;
A third step of processing the laminated joint body;
A layered manufacturing method for forming a desired layered structure by performing each of the steps using the same motion mechanism,
the motion mechanism being a three-axis feed mechanism of a machine tool that moves a main shaft to which a conveying tool for conveying the metal plate material in the first step, a joining tool for joining the metal plate material in the second step, and a processing tool for processing the laminated joint in the third step can be attached and detached, and to which compressed air can be supplied,
The first step to the third step are performed by selecting any one of the conveying tool, the joining tool, and the processing tool and mounting it on the spindle,
The conveying tool includes a holder having an air blow passage therein and detachable from the spindle, a vacuum ejector having an air supply port connected to the air blow passage of the holder via a pipe , and a vacuum pad connected to a vacuum port of the vacuum ejector,
The vacuum pad, which has a negative pressure inside, is adsorbed to the surface of the metal plate material and transported by passing compressed air supplied from the spindle through the air blow passage of the holder to the vacuum ejector.
In order to achieve the above object, a second aspect of the present invention provides a method for manufacturing a welding machine, comprising: a conveying means for conveying metal plate materials stored in a predetermined stock position to a predetermined processing position and stacking the metal plate materials on workpieces;
a joining means for joining the metal plate materials transported to the processing position together to form a laminated joint;
a processing means for processing the laminated joint body,
The conveying means, the joining means, and the processing means are operated by the same motion mechanism,
A layered manufacturing apparatus that forms a desired layered structure by carrying out the conveyance of the metal plate material by the conveyance means, the joining of the metal plate material by the joining means, and the processing of the layered joint body by the processing means,
the motion mechanism is a three-axis feed mechanism of a machine tool that moves a main shaft to which a conveying tool used in the conveying means, a joining tool used in the joining means, and a processing tool used in the processing means are detachably attached and to which compressed air can be supplied,
By selecting one of the conveying tool, the joining tool, and the processing tool and mounting it on the spindle, conveying the metal plate material, joining the metal plate material, and processing the laminated joint body are performed, while
the conveying tool includes a holder having an air blow passage therein and detachable from the spindle, a vacuum ejector having an air supply port connected to the air blow passage of the holder via a pipe , and a vacuum pad connected to a vacuum port of the vacuum ejector,
The present invention is characterized in that by passing compressed air supplied from the spindle through the air blow passage of the holder to the vacuum ejector, the vacuum pad, the inside of which is at negative pressure, can be adsorbed to the surface of the metal plate material and transported.
According to another aspect of the present invention, in the above configuration, the conveying tool, the joining tool, and the processing tool are further stocked in a tool stocker,
The three-axis feed mechanism is characterized in that it executes each of the means by exchanging the conveying tool, the joining tool, and the processing tool between the tool stocker and the three-axis feed mechanism.
Another aspect of the second invention is characterized in that, in the above-mentioned configuration, the stock position and the processing position are set on the same table.
According to another aspect of the present invention, in the above-mentioned configuration, a clamping device capable of moving up and down in a vertical direction to clamp/unclamp the metal plate material is provided at the processing position,
The clamping device is characterized in that it moves up and down based on information about the height of the laminated joint body.
Another aspect of the second invention is characterized in that, in the above configuration, a base for placing the workpiece is disposed on the processing position, and the base is configured so that its upper surface height can be adjusted.

According to the present disclosure, it is not necessary to provide a separate conveying device for the metal plate material, and therefore it is possible to automate the conveying and positioning of the metal plate material with a relatively inexpensive and space-saving configuration.
In addition, according to the clamping device disclosed herein, it is possible to reliably clamp even if the height of the laminated joint changes when metal plates are stacked, and it can also accommodate an increase in workpiece height due to additive manufacturing.

FIG. 1 is a schematic diagram of an additive manufacturing apparatus. FIG. FIG. 2 is a perspective view showing details of the table. 1 is a flowchart of an additive manufacturing method. 1A is a schematic diagram showing a state in which a workpiece is removed from a stock area, and FIG. 1B is a schematic diagram showing a state in which the workpiece has been transported to a processing area. 1A is a schematic diagram showing a state in which FSW is being performed, and FIG. 1B is a schematic diagram showing a state in which cutting is being performed. 13A is a schematic diagram showing the state in which the base block has been replaced, and FIG. 13B is a schematic diagram showing the state in which the clamp device has been raised. 13 is a flowchart of a modified example of the additive manufacturing method.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an example of an additive manufacturing apparatus. The additive manufacturing apparatus 1 includes a machine tool such as a vertical machining center. The additive manufacturing apparatus 1 has a spindle head 4 provided with a rotating spindle 5 facing downward on a column 3 erected on a bed 2. The spindle head 4 can move in the vertical direction by the Z axis. A table 6 is provided on the bed 2. The table 6 can move in two horizontal directions by the X and Y axes perpendicular to the Z axis. Each axis is driven by a servo motor controlled by a numerical control device (not shown) to form a three-axis feed mechanism. The relative position of the spindle head 4 with respect to the table 6 is controlled by this three-axis feed mechanism.

The additive manufacturing device 1 also includes a tool stocker 7. The tool stocker 7 stores an FSW tool 8, a cutting tool 9, and a transport tool 10 for a workpiece W, which is a metal plate material, and these can be automatically exchanged between the tool stocker 7 and the spindle 5.
The FSW tool 8 has a cylindrical shape with a pin (probe) 8a protruding from the center of the lower end. The cutting tool 9 is an end mill or the like used in machine tools.
The conveying tool 10 is of a suction type. An example is shown in Fig. 2. The conveying tool 10 includes a holder 11 that is detachably attached to the spindle 5 and has an air blow passage therein, a pipe 12 that is connected to the air blow passage of the holder 11, a vacuum ejector 13 that is connected to the pipe 12, and a vacuum pad 14 that is connected to the vacuum ejector 13. The vacuum ejector 13 has an air supply port 15 connected to the pipe 12 and a vacuum port 16 connected to the vacuum pad 14. Thus, compressed air supplied from the spindle head 4 is passed from the holder 11 through the pipe 12 to the vacuum ejector 13 and exhausted from an air exhaust port 17, thereby generating negative pressure in the vacuum pad 14 and enabling the workpiece W to be adsorbed to the surface of the workpiece W.

As shown in Fig. 3, a processing area A1 and a stock area A2 for the workpiece W are provided on the table 6. The processing area A1 includes a base block 20 fixed on the table 6 and a plurality of (four in this example) clamp devices 21, 21, ... arranged around the base block 20. Each clamp device 21 includes an air cylinder 23 with a clamp shaft 24 facing upward in a sleeve 22 standing upright. The clamp shaft 24 moves up and down by supplying air to the air cylinder 23. The air cylinder 23 rotates by a motor and a reduction mechanism (not shown). One end of a clamp arm 25 is attached to the upper end of the clamp shaft 24. A bolt 26 is screwed downward into the other end of the clamp arm 25.
In the stock area A2, a plurality of workpieces W, W... can be stacked in the thickness direction and stored inside a plurality of support rods 27, 27... that are erected upward.

A specific operation of the layered manufacturing process in the layered manufacturing device 1 configured as above will be described with reference to the flowchart of FIG.
When the machining program is loaded and machining is started, in S (STEP) 1, the transport tool 10 is attached to the spindle 5. Then, in S2, as shown in Fig. 5(A), the transport tool 10 is moved to the stock area A2, and the vacuum pad 14 is caused to adsorb the topmost workpiece W1 (written as "W1" to distinguish it from the other workpieces W). At this time, each clamp device 21 is waiting at the rotation position of the air cylinder 23 where the bolt 26 of the clamp arm 25 is retracted from above the base block 20 to the outside.
Next, in S3, the attracted workpiece W1 is transported to the processing area A1 and placed on the upper surface of the workpiece W fixed to the base block 20, as shown in FIG. 5(B) (S2, S3: first step).

Next, in S4, as shown in Fig. 5(B), the workpiece W1 is clamped by each clamp device 21. At this time, in each clamp device 21, the clamp shaft 24 is raised to the upper limit of the stroke, and then the air cylinder 23 is rotated to a rotation position where the bolt 26 of the clamp arm 25 is above the workpiece W1, and the clamp shaft 24 is lowered. As a result, each bolt 26 abuts against the outer edge of the workpiece W1 from above, clamping the workpiece W1. Note that the amount of lifting needs to be equal to or greater than the thickness of the workpiece W1, and the clamp shaft 24 does not necessarily have to be raised to the upper limit of the stroke.
After clamping, the suction of the transport tool 10 is released and the transport tool 10 is withdrawn from the processing area A1.

Next, in S5, the transfer tool 10 is replaced with the FSW tool 8, and in S6, as shown in Fig. 6(A), the FSW tool 8 is rotationally driven to perform FSW and join the uppermost workpiece W1 to the workpiece W (second step). As a result, a laminated joint body 30 is formed by stacking a plurality of workpieces W.
When joining is completed, in S7, as shown in Fig. 6(B), the clamping of the workpiece W1 by each clamping device 21 is released. That is, each clamping device 21 raises the clamping shaft 24 to move the bolt 26 of the clamping arm 25 away from the workpiece W1, and rotates the air cylinder 23 to retract the bolt 26 from above the workpiece W1 to the outside. Thereafter, the clamping shaft 24 is lowered. However, the clamping shaft 24 does not need to be lowered if it does not interfere with the cutting process.
In addition, the clamping may be released not only at the end of joining, but also during joining. In this way, even if there is a portion where joining is impossible due to interference from the clamping device 21, joining is possible by releasing the clamping.
Next, in S8, the FSW tool 8 is replaced with a cutting tool 9, and in S9, cutting of the laminated joint body 30 is performed (third step).

After the cutting process, if the contents read in S10 are the end of the program, the laminated structure is completed and the additive manufacturing ends. If the laminated structure is not completed, the processing continues. Specifically, the process returns to S1 and the operations from changing to the transport tool to the cutting process in S12 are repeated to complete the additive manufacturing.
At this time, the command read in can include a command to suspend processing and a command to notify the operator. That is, when it is expected that the upper surface height of the workpiece W1 will gradually rise as processing progresses and exceed the operating range of the clamp device 21, processing is suspended and the operator is prompted to take action to deal with the situation. Specifically, in S11, it is confirmed whether the next command read in S10 includes a processing stop command and a notification command, and if not, the work from S1 is repeated as the normal next processing operation as described above. If the processing stop command and the notification command are included in S11, processing is temporarily suspended in S12 and a notification is given to the operator.
For the sake of convenience, S10 to S12 are explained using process symbols for judgment, but in reality, whether the laminated structure is completed or not, and the timing when the workpiece upper surface height exceeds the clamp operation range are known at the stage of creating the machining program by CAM or an operator, so it is sufficient if a machining stop or notification command is simply inserted into the machining program. Also, for the sake of simplicity, the explanation is given as repeating the operations of S1 to S10, but in an actual machining program, the command may be written the required number of times.

The countermeasure for the notification is to replace the base block 20 with one having a smaller thickness as shown in Fig. 7(A), or to raise the sleeve 22 of each clamp device 21 using a spacer 22a or the like prepared in advance as shown in Fig. 7(B). If the difference between the top surface height and the upper limit of the lifting stroke range is small, it may be possible to adjust the position of the bolt 26. By determining in advance which of these is appropriate and incorporating this into the display when the notification is issued, the operator can perform the appropriate work without hesitation.
When the operator finishes the work and performs a predetermined reset operation (YES in S13), the process returns to S1, the cutting tool 9 is replaced with the transport tool 10, and the process from S2 onwards is repeated. This eliminates the limitation of the stroke of the lifting device of the clamp device 21, and allows the size of the additive manufacturing to be increased.
In addition, when replacing the base block 20 with one of a different thickness, the height of the top surface of the workpiece W1 will change, so it goes without saying that a program should be created that notifies the operator of the thickness to be replaced in advance and that processes the workpiece W1 to match its height after replacement, or that a correction value should be input so that processing can be performed to match the height of the workpiece W1 after base block replacement before the operator performs the reset operation.

Incidentally, the operation of the clamping device described above is not limited to that planned in advance by a machining program or the like, but can be judged and operated in real time. A specific operation will be described with reference to the flow chart of Fig. 8. Since steps S1 to S10 are the same as those in Fig. 4, the description will be omitted.
If the program is ended in S10, the laminated structure is completed, and the laminated manufacturing ends. If the laminated structure is not completed, in S21, it is determined whether the workpiece W1 to be conveyed next can be clamped by the clamping device 21. This determination can be made in advance when the NC program input to the control device of the laminated manufacturing device 1 is created as described above, but it can also be calculated from the position information of the cutting tool 9 during the immediately preceding upper surface processing. In addition, the upper surface height of the workpiece W1 may be detected and determined whether the upper surface height is within the lifting stroke range of the clamping device 21. The upper surface height can be detected, for example, using a non-contact sensor such as a reflective laser sensor, or calculated from the number of conveyed workpieces W, the thickness of the workpieces W, and the amount of thickness reduction due to cutting. If the result of S21 is YES, that is, if it is determined that the next workpiece W1 can be clamped, the process returns to S1, the cutting tool 9 is replaced with the conveying tool 10, and the process from S2 onwards is repeated.
If it is not possible to clamp the workpiece W1 in S21 (NO in S21: the upper surface height is not within the lifting stroke range), the processing by the additive manufacturing device 1 is temporarily stopped in S12, and a notification is issued to prompt the operator to take action. The subsequent processing is the same as in FIG.

In this way, in the above-described form of additive manufacturing apparatus 1, the first step (transporting means) of transporting the workpiece W1 stored in the stock area A2, which is a designated stock position, to the processing area A1, which is a designated processing position, and stacking it on top of the workpiece W (joined body) that has previously been transported, joined and processed, the second step (joining means) of joining the workpiece W transported in the first step to the workpiece W to form a laminated joint 30, and the third step (processing means) of processing the laminated joint 30 are repeatedly performed to form a desired laminated structure, using the same motion mechanism, a three-axis feed mechanism.
This configuration eliminates the need to provide a separate transport device for the workpieces W. Therefore, the transport and placement of the workpieces W can be automated with a relatively inexpensive and space-saving configuration.

In particular, the three-axis feed mechanism moves (relative movement with the workpiece W) a spindle 5 to which a transport tool 10 for transporting the workpiece W in the first step, an FSW tool 8 which is a joining tool for joining the workpiece W in the second step, and a cutting tool 9 which is a processing tool for machining the laminated joint 30 in the third step can be detachably attached (relative movement with the workpiece W). By selecting and attaching one of the transport tool 10, the FSW tool 8, and the cutting tool 9 to the spindle 5, it is possible to perform the first to third steps (transport means, joining means, processing means).
Therefore, by replacing each tool with respect to the spindle 5, each process (each means) can be performed efficiently.

The system further includes a tool stocker 7 for stocking a transport tool 10, an FSW tool 8, and a cutting tool 9, and the three-axis feed mechanism exchanges the transport tool 10, the FSW tool 8, and the cutting tool 9 between the tool stocker 7 and performs each process (each means).
Therefore, transition between each process can be carried out smoothly and an increase in the machine installation area can be suppressed.
The processing area A1 and the stock area A2 are set on the same table 6. Therefore, the workpiece W can be transported to the processing area A1 in a short time.

On the other hand, a clamping device 21 capable of moving up and down to clamp/unclamp the workpiece W is provided in the processing area A1, and the clamping device 21 moves up and down based on information on the total stroke or the height of the laminated joint body 30.
Therefore, even if the workpieces W are stacked and the height of the laminated joint body 30 changes, the workpieces W can be securely clamped.

The following describes a modified example.
The conveying tool is not limited to the above-mentioned form. For example, there may be multiple vacuum pads, an electromagnet/permanent magnet may be used if the workpiece is magnetic, or a conveying tool other than suction (such as a robot arm) may be used depending on the shape of the workpiece.
The method of joining workpieces is not limited to FSW. Plasma welding, laser welding, electron beam welding, etc. can also be used. Therefore, the joining tool can be changed according to the joining method.
The machining tools may be replaced with a plurality of different types to perform different machining in the third step.
The metal plate materials may be laminated and processed not only one layer at a time, but also multiple layers at a time.

In the above embodiment, the first step (transport), the second step (joining), and the third step (processing) are each performed once in sequence, but this is not limiting, and each step may be performed multiple times. For example, it is possible to perform the first step (transport) multiple times and then perform the second step (joining) and the third step (processing) once each, or to repeat a set of the first step (transport) and the second step (joining) multiple times and then perform the third step (processing).
The number and arrangement of the clamping devices can be changed as appropriate. The structure of the clamping device itself can also be changed as appropriate, and other actuators such as hydraulic cylinders and ball screws can be used instead of air cylinders. Clamping can also be achieved by lowering the base block or table to match the top surface height of the workpiece. Furthermore, instead of the base block, a base having an internal mechanism for adjusting the top surface height can be used, and the top surface height can be adjusted to match the top surface height of the workpiece. The adjustment mechanism can be a general mechanism such as a feed screw or link mechanism also used in machine tools, and the operation can be manual or controlled by a numerical control device or a machining program.

1: Additive manufacturing device, 2: Bed, 3: Column, 4: Spindle head, 5: Spindle, 6: Table, 7: Tool stocker, 8: FSW tool, 9: Cutting tool, 10: Transport tool, 13: Vacuum ejector, 14: Vacuum pad, 20: Base block, 21: Clamping device, 22: Sleeve, 23: Air cylinder, 24: Clamping shaft, 25: Clamping arm, 26: Bolt, 30: Laminated joint, A1: Processing area, A2: Stock area, W (W1): Workpiece.

Claims (6)

A first step of transporting metal plate materials stored at a predetermined stock position to a predetermined processing position and stacking them on workpieces;
a second step of joining the metal plate material transported in the first step to the workpiece to form a laminated joint body;
A third step of processing the laminated joint body;
A layered manufacturing method for forming a desired layered structure by performing each of the steps using the same motion mechanism,
the motion mechanism being a three-axis feed mechanism of a machine tool that moves a main shaft to which a conveying tool for conveying the metal plate material in the first step, a joining tool for joining the metal plate material in the second step, and a processing tool for processing the laminated joint in the third step can be attached and detached, and to which compressed air can be supplied,
The first step to the third step are performed by selecting any one of the conveying tool, the joining tool, and the processing tool and mounting it on the spindle,
The conveying tool includes a holder having an air blow passage therein and detachable from the spindle, a vacuum ejector having an air supply port connected to the air blow passage of the holder via a pipe , and a vacuum pad connected to a vacuum port of the vacuum ejector,
An additive manufacturing method, characterized in that compressed air supplied from the spindle is passed from the air blow passage of the holder to the vacuum ejector, thereby adsorbing the vacuum pad, which has a negative pressure inside, to the surface of the metal plate material and transporting it. A conveying means for conveying the metal plate material stored at a predetermined stock position to a predetermined processing position and stacking it on the workpiece;
a joining means for joining the metal plate material transported to the processing position to the workpiece to form a laminated joint;
a processing means for processing the laminated joint body,
The conveying means, the joining means, and the processing means are operated by the same motion mechanism,
A layered manufacturing apparatus that forms a desired layered structure by carrying out the conveyance of the metal plate material by the conveyance means, the joining of the metal plate material by the joining means, and the processing of the layered joint body by the processing means,
the motion mechanism is a three-axis feed mechanism of a machine tool that moves a main shaft to which a conveying tool used in the conveying means, a joining tool used in the joining means, and a processing tool used in the processing means are detachably attached and to which compressed air can be supplied,
By selecting one of the conveying tool, the joining tool, and the processing tool and mounting it on the spindle, conveying the metal plate material, joining the metal plate material, and processing the laminated joint body are performed, while
the conveying tool includes a holder having an air blow passage therein and detachable from the spindle, a vacuum ejector having an air supply port connected to the air blow passage of the holder via a pipe , and a vacuum pad connected to a vacuum port of the vacuum ejector,
An additive manufacturing device characterized in that compressed air supplied from the spindle is passed from the air blow flow path of the holder to the vacuum ejector, thereby allowing the vacuum pad, which has a negative pressure inside, to be adsorbed to the surface of the metal plate material and transported. The machine further includes a tool stocker for stocking the conveying tool, the joining tool, and the processing tool ,
The additive manufacturing device according to claim 2 , wherein the three-axis feed mechanism executes each of the steps by exchanging the conveying tool, the joining tool, and the processing tool between the tool stocker and the three-axis feed mechanism. 4. The layered manufacturing apparatus according to claim 2, wherein the stock position and the processing position are set on the same table. A clamping device capable of moving up and down in a vertical direction to clamp/unclamp the metal plate material is provided at the processing position,
5. The layered manufacturing apparatus according to claim 2, wherein the clamping device moves up and down based on information on the height of the layered joint body. 5. The additive manufacturing apparatus according to claim 2, wherein a base for placing the workpieces is disposed above the processing position, and the height of an upper surface of the base is adjustable.

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