JP6859471B1 - Manufacturing method of laminated model - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a laminated model capable of suppressing the occurrence of internal defects between adjacent welded beads. SOLUTION: In a method of manufacturing a laminated model, a welded bead 25 obtained by melting and solidifying a filler metal is adjacent to each other to form a welded bead layer 34, and a next layer of welded bead is formed on the formed welded bead layer 34. The layers 34 are repeatedly laminated to form a model. When forming the welding bead layer 34, the cross-sectional shape of each welding bead 25 is approximated to a trapezoidal shape, the height of the approximated trapezoidal shape is H, the base angle is θ, and the overlapping portion between the adjacent welding bead 25s. The welding bead is formed so as to satisfy either of the following conditions (A) and (B), where h is the height of. Condition (A): The base angle θ is less than 41.7 °, Condition (B): θ <-33.18 × ln (H / h) +65.973, and H / h ≧ 2.078 [Selection diagram] Figure 4

Description

The present invention relates to a method for producing a laminated model.

In recent years, there has been an increasing need for modeling using a 3D printer as a means of production, and research and development are being promoted toward the practical application of modeling using metal materials. A 3D printer for modeling a metal material uses a laser, an electron beam, or a heat source such as an arc to melt a metal powder or a metal wire, and laminates the molten metal to produce a laminated model.

As a technique for producing such a laminated model, for example, Patent Document 1 discloses a welding technique for automatically generating a welding path of a welding torch by setting overlapping conditions between welding beads. In the setting of the overlap condition, it is described that the occurrence of welding defects is avoided by adjusting the amount of overlap between the welding beads.

Japanese Unexamined Patent Publication No. 2016-196012

However, in Patent Document 1, the welding path is generated based on the bead width of the welded bead and the lateral overlap amount with respect to the bead width, but the setting of the lateral overlap amount is specifically described. Not. Therefore, further improvement is desired in order to suppress defects by a welding path according to the welding conditions when forming a welded bead.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a laminated molded product capable of suppressing the occurrence of defects between adjacent welded beads.

The above object of the present invention is achieved by the method for producing a laminated model according to the following (1).
(1) A laminated model in which welded beads obtained by melting and solidifying a filler metal are adjacent to each other to form a welded bead layer, and a next-layer welded bead layer is repeatedly laminated on the formed welded bead layer. It is a manufacturing method of
When forming the welding bead layer, the cross-sectional shape of each welding bead is approximated to a trapezoidal shape.
When the height of the approximated trapezoidal shape is H, the base angle is θ, and the height of the overlapping portion between the adjacent welded beads is h, one of the following conditions (A) and (B) is satisfied. A method for producing a laminated model, which forms the welded bead so as to satisfy the requirements.
Condition (A): The base angle θ is less than 41.7 ° Condition (B): θ [°] <-33.18 × ln (H / h) +65.973, and H / h ≧ 2.078

According to the method for producing a laminated model of the present invention, it is possible to suppress the occurrence of internal defects between adjacent welded beads.

It is a schematic block diagram of the manufacturing apparatus which manufactures a laminated model using the manufacturing method of a laminated model which concerns on this invention. It is a perspective view which shows an example of the laminated shaped object formed by a plurality of welding bead layers. It is sectional drawing which shows an example which approximated the adjacent welding bead to a trapezoid shape among the welding bead layer of the first layer formed on the base plate. It is sectional drawing which shows another example which approximated the adjacent welding bead to a trapezoid shape among the welding bead layer of the first layer formed on the base plate. It is a graph which shows the examination result of the condition that the gap does not occur between welding beads.

Hereinafter, a method for manufacturing a laminated model according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a manufacturing apparatus for manufacturing a laminated model using the method for manufacturing a laminated model according to the present invention. The manufacturing device 100 having this configuration includes a laminated modeling device 11 and a controller 15 that controls the laminated modeling device 11 in an integrated manner.

The laminated modeling device 11 includes a welding robot 19 having a torch 17 on the tip shaft, and a filler material supply unit 23 that supplies a filler metal (welding wire) M to the torch 17.
The controller 15 includes a CAD / CAM unit 31, an orbit calculation unit 33, a storage unit 35, and a control unit 37 to which each of these units is connected.

The welding robot 19 is an articulated robot, and the filler metal M is supported on the torch 17 of the tip shaft so that it can be continuously supplied. The position and posture of the torch 17 can be arbitrarily set three-dimensionally within the range of the degree of freedom of the robot arm.

The torch 17 has a shield nozzle (not shown), and shield gas is supplied from the shield nozzle. The welding method using the torch 17 may be either a consumable electrode type such as shielded metal arc welding or carbon dioxide arc welding, or a non-consumable electrode type such as TIG welding or plasma arc welding. Be selected.

For example, in the case of the consumable electrode type, the contact tip is arranged inside the shield nozzle, and the filler metal M to which the melting current is supplied is held by the contact tip. The torch 17 generates an arc from the tip of the filler metal M in a shield gas atmosphere while holding the filler metal M. The filler metal M is fed from the filler metal supply unit 23 to the torch 17 by a feeding mechanism (not shown) attached to a robot arm or the like.

The CAD / CAM unit 31 creates shape data of the laminated model to be manufactured. After creating the shape data of the laminated model, the CAD / CAM unit 31 divides the laminated model into a plurality of layers to generate layer shape data representing the shape of each layer. The trajectory calculation unit 33 obtains the movement trajectory of the torch 17 based on the layer shape data generated by the CAD / CAM unit 31. The storage unit 35 stores the layer shape data generated by the CAD / CAM unit 31, the data of the movement locus of the torch 17 obtained by the trajectory calculation unit 33, and the like.

The control unit 37 drives the welding robot 19 by executing a drive program based on the layer shape data stored in the storage unit 35 and the data of the movement locus of the torch 17. That is, the welding robot 19 moves the torch 17 while melting the filler metal M with an arc based on the trajectory trajectory of the torch 17 generated by the trajectory calculation unit 33 in response to a command from the controller 15.

The manufacturing apparatus 100 having the above configuration melts the filler metal M while moving the torch 17 by driving the welding robot 19 along the movement locus of the torch 17 generated from the set layer shape data, and melts the melted filler metal. Material M is supplied onto the base plate 27. By repeatedly melting and solidifying the filler metal M that is continuously fed while moving the torch 17, linear welded beads 25 that are the molten and solidified bodies of the filler metal M are arranged in a row on the base plate 27. They are lined up to form the welded bead layer 34.

As shown in FIG. 2, the welding bead layer 34 is formed by repeatedly forming a plurality of welding beads 25 adjacent to each other. The laminated model W is formed by laminating a plurality of similar welded bead layers 34 on the welded bead layer 34 in which the welded beads 25 are arranged side by side.

The base plate 27 is made of a metal plate such as a steel plate, and basically, a base plate 27 larger than the bottom surface (bottom layer surface) of the laminated model is used. The base plate 27 is not limited to a plate shape, and may be a base having another shape such as a block body or a rod shape. As the filler metal M, any commercially available welding wire can be used. For example, it is defined by MAG welding and MIG welding solid wire for mild steel, high-strength steel and low-temperature steel (JIS Z 3312), arc welding flux-welded wire for mild steel, high-tensile steel and low-temperature steel (JIS Z 3313), and the like. Wire can be used.

Here, the shape of each welded bead 25 constituting the welded bead layer 34 is a feeding speed for supplying the filler metal M to the torch 17, a voltage value or a current value applied to the torch 17, and the torch 17 on the base plate 27. It is determined by the welding conditions such as the welding speed of linearly moving relative to.

For example, FIG. 3 shows two welded beads 25 having a horizontally long cross-sectional shape, and FIG. 4 shows a base angle θ and a height H formed by the cross-sectional shape being larger than those of FIG. 3, and formed adjacent to each other. Two welded beads 25 are shown in which the height h of the overlapping portion of the welded beads is larger than that in FIG. When the welded beads 25 having these cross-sectional shapes are formed side by side, it is considered that the molten metal sufficiently flows to the hem of the adjacent beads and fuses because θ is small in FIG. However, in the welded bead 25 of FIG. 4, since θ is a relatively large condition, the fluidity of the molten metal is low, and there is a possibility that a gap may be generated without promoting sufficient fusion with the hem portion of the adjacent bead. is there.

Therefore, the present inventor has focused on the relationship between the cross-sectional shape of the welding beads 25 and the amount of overlap between the adjacent welding beads 25 in order to suppress the occurrence of gaps between the welding beads 25. Specifically, the cross-sectional shape of the welded bead 25 is approximated to a trapezoidal shape, the height H of the approximated trapezoidal shape 41, the base angle θ, and the overlapping portion of the welded beads 25 formed adjacent to each other. The relationship with the height (in the figure, the height from the base plate 27 to the narrow portion N formed between the adjacent weld beads 25) h was examined. The trapezoidal approximation of the welding bead 25 can be performed by measuring the cross-sectional shape of the welding bead 25 using, for example, a laser or the like, and approximating the measured cross-sectional shape with the trapezoidal shape.

FIG. 5 is a graph showing the results of examining the relationship between the height H of the approximated trapezoidal shape, the base angle θ, and the height h of the overlapping portion of the welded beads 25 formed adjacent to each other. .. In the graph shown in FIG. 5, the vertical axis represents the base angle θ of the approximate trapezoidal shape, and the horizontal axis represents the ratio H / h of the approximate height H of the trapezoidal shape to the height h of the overlapping portion. Further, in the graph, the “◯” mark indicates a sample in which no gap is generated between the welding beads 25, and the “x” mark indicates a sample in which a gap is generated between the welding beads 25.

For example, in sample S1, when the base angle θ of the approximate trapezoidal shape is set to 40 °, the welding bead is set to 2 when the ratio H / h of the approximated trapezoidal height H to the height h of the overlapping portion is set to 2. It shows that no gap is generated between 25. Further, in the sample S2, when the base angle θ of the approximated trapezoidal shape is set to 45 °, the ratio H / h of the approximated trapezoidal height H to the height h of the overlapping portion is set to 1.4. This indicates that no gap is generated between the weld beads 25. Further, in the sample S3, when the base angle θ of the approximate trapezoidal shape is set to 45 °, the ratio H / h of the approximated trapezoidal height H to the height h of the overlapping portion is set to 2.5. This indicates that a gap is generated between the weld beads 25.

From these examination results, the present inventor, based on the qualitative findings obtained from FIGS. 3 and 4 and the experimental results of FIG. 5, when the base angle θ of the approximate trapezoidal shape is 41.7 ° or more, By forming adjacent welding beads 25 so as to satisfy θ <−33.18 × ln (H / h) +65.973 and H / h ≧ 2.078, no gap is generated between the welding beads 25. I found. It was also found that the relationship between H and h can be arbitrarily set when the base angle θ of the approximate trapezoidal shape is less than 41.7 °.

Therefore, in the present embodiment, the above two relationships are stored in the storage unit 35 of the controller 15 as a table, and the height H and the bottom of the approximate trapezoidal shape (welding bead) in which no gap is generated between the welding beads 25. The welding conditions of the welding beads 25 are obtained so as to satisfy the relationship between the angle θ and the height h of the overlapping portion between the adjacent welding beads 25. Therefore, these parameters of height H, base angle θ, and height h, the feeding speed of the filler metal M, the voltage value and current value applied to the torch 17, the welding speed, and the adjacent welding bead 25 It is preferable to create a database by associating the relationships with welding conditions such as the pitch between them and to store these relationships in the storage unit 35 as well. Further, in order to reduce H / h, for example, the pitch interval between adjacent beads may be reduced, and in order to reduce θ, the amount of heat input may be increased. Therefore, the above relationship is based on a predetermined welding condition. The pitch interval and the amount of heat input may be adjusted so as to satisfy the above conditions.

Next, an example of the procedure for forming the welded bead layer 34 will be described in detail using the above table found by the above examination results.

First, the shape of the welded bead 25 for forming the welded bead layer 34 is grasped. The shape of the welded bead 25 is given by the base angle θ and the height H of the trapezoidal shape when the welded bead 25 is approximated to an isosceles trapezoidal shape. These values may be obtained by measuring the base angle θ and the height H with respect to the actually formed welded bead 25, or some welding conditions are determined and stored in the storage unit 35. It may be obtained using the database. Further, when using a database, only the base angle θ may be obtained.

Then, by selecting the base angle θ of the trapezoidal shape, an internal defect (gap) does not occur, and the welding bead adjacent to the height H of the welding bead 25 stored in the storage unit 35 in association with the bottom angle θ. The range of the combination value (H / h) of the height h of the overlapping portion of 25 is selected.
Further, when the measured height H of the trapezoidal shape is given, the range of the height h of the overlapping portion between the adjacent welded beads 25 in which internal defects do not occur is obtained, and the desired height h is given. , The welding conditions such as the feeding speed of the filler metal M, the voltage value and the current value applied to the torch 17, the welding speed, and the pitch between the adjacent welding beads 25 are set.
Further, when only the base angle θ using the database is set, the height H of the trapezoidal shape and the height h of the overlapping portion that satisfy the combination value (H / h) are given, and the filler metal M Welding conditions such as feeding speed, voltage value and current value applied to the torch 17, welding speed, and pitch between adjacent welding beads 25 are set.

The control unit 37 determines the welding conditions such as the feed rate of the filler metal M, the voltage value and current value applied to the torch 17, the welding speed, the pitch between the adjacent welding beads 25, and the laminated modeled object. The welding robot 19 is driven by executing a drive program based on data such as layer shape data and the movement locus of the torch 17. The welding robot 19 repeatedly melts and solidifies the welded material M that is continuously fed while moving the torch 17, so that the welding beads 25 are formed in parallel on the base plate 27 so as to be adjacent to each other, and the first layer is formed. The welded bead layer 34 is formed.

Further, the welding bead layer 34 of the next layer to be laminated on the welding bead layer 34 of the first layer is also formed by the same procedure, and a plurality of welding bead layers 34 are repeatedly laminated to obtain a desired laminated model. Make a model.

As described above, according to the method for manufacturing a laminated model according to the above embodiment, the shape of the welded bead 25 is approximated to the trapezoidal shape, the height H of the approximated trapezoidal shape (welded bead), and the base angle θ. And each welding bead layer 34 is formed based on the relationship with the height h of the overlapping portion between the welding beads 25 formed adjacent to each other. When the base angle θ is 41.7 ° or more, the adjacent welding beads 25 so as to satisfy θ <−33.18 × ln (H / h) +65.973 and H / h ≧ 2.078. When they are formed and the base angle θ is less than 41.7 °, the heights H and h are arbitrarily set to form adjacent weld beads 25. That is, the condition (A): the base angle θ is set to less than 41.7 °, or the condition (B): θ <-33.18 × ln (H / h) +65.973 and H / h ≧ 2.078. By satisfying any of the conditions, the molten filler M can be satisfactorily penetrated into the gap between the adjacent welding beads 25, and the occurrence of internal defects (gap) between the welding beads 25 is suppressed. can do.

As described above, the following matters are disclosed in this specification.
(1) A laminated model in which welded beads obtained by melting and solidifying a filler metal are adjacent to each other to form a welded bead layer, and a next-layer welded bead layer is repeatedly laminated on the formed welded bead layer. It is a manufacturing method of
When forming the welding bead layer, the cross-sectional shape of each welding bead is approximated to a trapezoidal shape, the height of the approximated trapezoidal shape is H, the base angle is θ, and the overlapping between the adjacent welding beads. A method for producing a laminated model, wherein the welded bead is formed so as to satisfy any of the following conditions (A) and (B), where h is the height of the portion.
Condition (A): The base angle θ is less than 41.7 ° Condition (B): θ <-33.18 × ln (H / h) +65.973, and H / h ≧ 2.078
According to this method for manufacturing a laminated model, it is possible to suppress the occurrence of internal defects between adjacent welded beads.

(2) The method for manufacturing a laminated model according to (1), wherein the pitch interval between adjacent welded beads is reduced so as to reduce H / h.
According to this method for manufacturing a laminated model, by adjusting the pitch interval, it becomes easy to set conditions for suppressing the occurrence of internal defects between adjacent welded beads.

(3) The method for producing a laminated model according to (1) or (2), wherein the heat input amount of the welded bead is increased so as to reduce the base angle θ.
According to this method for manufacturing a laminated model, by adjusting the amount of heat input, it becomes easy to set conditions for suppressing the occurrence of internal defects between adjacent welded beads.

11 Laminated molding device 15 Controller 17 Torch 19 Welding robot 23 Welding material supply unit 25 Welding bead 31 CAD / CAM unit 33 Orbital calculation unit 34 Welding bead layer 35 Storage unit 37 Control unit 41 Trapezoidal shape 100 Manufacturing device θ Trapezoidal bottom Square H Trapezoidal height h Overlapping part height M Welding material N Narrow part W Laminated model

Claims (3)

A method for producing a laminated model in which welded beads obtained by melting and solidifying a welding material are adjacent to each other to form a welded bead layer, and a next-layer welded bead layer is repeatedly laminated on the formed welded bead layer. And
When forming the welding bead layer, the cross-sectional shape of each welding bead is approximated to a trapezoidal shape, the height of the approximated trapezoidal shape is H, the base angle is θ, and the overlapping between the adjacent welding beads. A method for producing a laminated model, wherein the welded bead is formed so as to satisfy any of the following conditions (A) and (B), where h is the height of the portion.
Condition (A): The base angle θ is less than 41.7 ° Condition (B): θ [°] <-33.18 × ln (H / h) +65.973, and H / h ≧ 2.078 The method for manufacturing a laminated model according to claim 1, wherein the pitch interval between the adjacent welded beads is reduced so as to reduce the H / h. The method for producing a laminated model according to claim 1 or 2, wherein the amount of heat input to the welded bead is increased so as to reduce the base angle θ.

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