JP5515557B2 - Metal processing method and boss forming jig - Google Patents

Description

  The present invention relates to a metal processing method and a boss forming jig for forming protrusions on a metal plate or the like.

  As a casing material for electronic devices such as notebook computers and mobile phones, magnesium alloys, aluminum alloys, and the like, which are light and strong, and are more recyclable than plastic materials such as plastics, have come to be used. A casing made of these light metals is generally manufactured by a thixo molding method or a die casting method.

  However, the thixomolding method and the die-casting method have the disadvantages that traces of movement of burrs and materials (molten metal) tend to remain after molding, post-processing is complicated, and the manufacturing cost is increased. On the other hand, if a casing is manufactured by pressing a metal plate, it is possible to manufacture a casing having an appearance that is superior to that of a casing manufactured by a thixomolding method or a die-cast method at a low cost. The housing of the electronic device is provided with bosses (protrusions) for screwing built-in parts and assembling the housings. As a method of forming the boss on the surface of the metal plate, the metal tube is attached to the metal plate. A method of joining the surface by stud welding is known. Therefore, it is possible to manufacture an electronic device casing from a metal plate using this technique.

  As another method, there has been proposed a method in which another metal plate is attached to the surface of a metal plate to be a casing and strongly pressed against the metal plate while rotating a hollow cylindrical jig. In this method, the surface of the metal plate plastically flows due to frictional heat generated between the jig and the metal plate, and the metal rises along the inner surface of the jig to form a hollow protrusion (boss). Further, the hollow protrusion is pressed against a metal plate serving as a casing.

JP 2007-14967 A JP 2009-107006 A

  In any of the above-described methods, the member serving as the boss and the metal plate serving as the housing are joined by welding or pressure welding. For this reason, it is considered that the bonding strength between the housing and the boss is not sufficient, and the reliability is low.

  Further, in the method of forming the boss by stud welding, there is also a problem that a welding mark remains on the surface opposite to the surface on which the boss is formed, and the appearance of the housing is impaired.

  Accordingly, it is an object of the present invention to provide a metal processing method and a boss forming jig capable of forming a boss that can be easily obtained with a beautiful appearance and that has high mechanical strength with the casing.

  According to one aspect, the process of causing the metal to plastically flow by rotating while pressing the processing jig against the metal material, and the plastic flowed metal in a groove provided on the surface of the processing jig where the metal material contacts And forming a protrusion having a shape following the shape of the groove on the surface of the metal material, and the edge of the surface of the processing tool on the metal material side is parallel to the rotation axis of the processing tool. A metal working method having a protruding portion protruding in any direction is provided.

  According to the one aspect described above, the edge of the surface on the metal material side (processing surface) of the processing jig has a protruding portion that protrudes in a direction parallel to the rotation axis of the processing jig. When the processing jig is rotated and strongly pressed against the metal material, the temperature of the metal material rises due to frictional heat, and the metal easily plastically flows. A part of the plastic fluidized metal enters a groove provided in the processing jig to form a protrusion, while the other part moves to the side by the pressure applied by the processing jig and becomes a burr. Moreover, when the metal which exists under a processing jig decreases, a hollow will occur easily on the back surface side of a metal material.

  However, according to the above one aspect, since the protruding portion is provided at the edge of the processing surface of the processing jig, the protruding portion serves as a wall, and the metal used for plastic flow is pushed back to the inside of the processing jig. . Thereby, generation | occurrence | production of the dent on the back side of a burr | flash or a metal material is suppressed. In addition, according to the above one aspect, the metal in the metal material is plastically flowed to form the protrusion, so that the metal material and the metal material are compared with the method of welding or press-contacting another metal member that becomes the protrusion to the metal material. The mechanical strength between the protrusions is high.

FIG. 1 is a schematic diagram illustrating a structure of a metal processing apparatus according to an embodiment. FIG. 2 is a longitudinal sectional view of the boss forming jig. 3A to 3C are cross-sectional views showing a metal processing method using a metal processing apparatus in the order of steps. FIG. 4 is a cross-sectional view showing a problem when the boss forming jig is not provided with a protrusion. Fig.5 (a) is a perspective view which shows an example of the boss | hub formed by the metal processing method, FIG.5 (b) is the sectional drawing similarly. It is sectional drawing which shows the boss | hub formation jig | tool of a comparative example. 7A and 7B are cross-sectional views showing a modified example (No. 1) of the boss forming jig. FIG. 8 is a cross-sectional view showing a modification (No. 2) of the boss forming jig. FIG. 9 is a cross-sectional view showing a modification (No. 3) of the boss forming jig.

  Hereinafter, embodiments will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing the structure of a metal processing apparatus according to this embodiment. As shown in FIG. 1, the metal processing apparatus 10 according to the embodiment includes an XY table 11, a motor 13, a pressing mechanism unit 14, and a control unit 15. The metal plate 30 to be processed is held on the XY table 11. The XY table 11 moves in the horizontal direction (X-axis direction and Y-axis direction) while holding the metal plate 30 in response to a signal from the control unit 15.

  The motor 13 is disposed above the XY table 11 with its rotating shaft facing down. A chuck 12 is provided on the rotating shaft of the motor 13, and a boss forming jig (processing jig) 1 is attached to the chuck 12 in a replaceable manner. Further, the motor 13 is driven by the pressing mechanism unit 14 and moves in the vertical direction. The control unit 15 controls the XY table 11, the motor 13, and the pressing mechanism unit 14 according to a preset procedure.

  FIG. 2 is a longitudinal sectional view of the boss forming jig 1. The boss forming jig 1 is formed in a cylindrical shape, and the lower surface thereof is a processed surface 1 a that contacts the metal plate 30. Further, an annular groove 1b that defines the shape of the boss is provided on the processing surface 1a side of the jig 1. Furthermore, the edge part of the process surface 1a is provided with the protrusion part 1c which protrudes below.

In the jig 1 of this embodiment, the inner diameter φ ₁ of the groove 1b is about 2.4 mm, the outer diameter φ ₂ is about 5.0 mm, and the groove depth D is about 5.0 mm. Further, the outer diameter φ ₃ of the jig 1 is set to about 8 mm, the height H of the protruding portion 1c is set to about 0.3 mm, and the curvature radius R of the inner surface of the protruding portion 1c is set to about 0.3 mm. In addition, the dimension of these each part is suitably set according to the magnitude | size of the boss | hub which should be formed.

  The boss forming jig 1 is formed of a material whose melting point is higher than the temperature at which the metal constituting the metal plate 30 to be processed causes plastic flow. In the present embodiment, the metal plate 30 is made of Mg (magnesium), Al (aluminum), Ti (titanium) or an alloy mainly composed of those metals, and the boss forming jig 1 is made of stainless steel (SUS304). To do.

  3A to 3C are cross-sectional views showing a metal processing method using the above-described metal processing apparatus in the order of steps.

  First, as shown in FIG. 3A, the metal plate 30 is held on the XY table 11 of the metal processing apparatus 10. And the motor 13 is driven by the signal output from the control part 15, and the boss | hub formation jig | tool 1 is rotated at the speed of 5000 rpm or more, for example, the speed of 8000 rpm-10000 rpm. Further, the XY table 11 is driven by a signal output from the control unit 15, and a predetermined portion of the metal plate 30 is disposed below the jig 1.

  In addition, in order to make a plastic flow easy to occur at the process mentioned later, it is preferable to heat the metal plate 30 to about 200 degreeC previously. The rotational speed of the motor 13 may be set as appropriate in consideration of the material of the metal plate 30 and the size of the jig 1.

  Next, as shown in FIG. 3B, while the rotation of the motor 13 is continued, the pressing mechanism unit 13 is driven by a signal output from the control unit 15 to lower the motor 13, and the boss forming jig 1 The processed surface 1a is pressed against the metal plate 30 so that the friction pressure becomes 15 MPa or more, for example. As a result, frictional heat is generated between the boss forming jig 1 and the metal plate 30, the temperature of the metal plate 30 rises, the metal in the metal plate 30 plastically flows, and an arrow in FIG. As shown in FIG. At this time, plastic flow of the metal also occurs in the direction toward the outside of the jig 1 due to the pressing pressure of the jig 1. However, in this embodiment, since the protrusion part 1c is provided in the edge part of the process surface 1a of the jig 1, the metal which goes outside this protrusion part 1c is pushed back inside.

  If the boss forming jig 1 does not have the protruding portion 1c, the plastically flowing metal is pushed out of the jig 1 as shown in FIG. 4 and a large burr 3 is generated around the jig 1. Therefore, the post-processing process for removing the burrs 3 becomes complicated and causes an increase in product cost. In addition, when the thickness of the metal plate 30 is as thin as about 1 mm, for example, the metal is insufficient in the lower portion of the groove 1b, and the metal plate 30 is depressed on the outer surface (the lower surface in FIG. 4). Sink ") 4 occurs, resulting in poor appearance.

  On the other hand, in this embodiment, since the protrusion part 1c is provided in the edge part of the processing surface of the boss | hub formation jig 1, as mentioned above, the protrusion part 1c becomes a wall and pushes back the metal which plastically flows inside. Therefore, no large burrs are generated on the outside of the jig 1, and even when the metal plate 30 is as thin as about 1 mm, for example, it is possible to prevent the formation of a dent that causes poor appearance.

It is preferable that the outer diameter φ ₃ of the jig 1 is 1.5 times or more the outer diameter φ ₂ of the groove 1 b, so that the plastically flowed metal can be more reliably suppressed from flowing out of the jig 1. .

  As described above, after the jig 1 is pressed against the metal plate 30, it is held for a certain period of time until the metal sufficiently flows into the groove 1b. At this time, the temperature of the metal plate 30 increases due to the friction between the metal plate 30 and the jig 1, or in this embodiment, the temperature at which the metal is easily plastically deformed due to the friction between the metal plate 30 and the jig 1 (for example, 200 ° C. to 300 ° C.), and it is not necessary to raise the temperature until the metal is melted.

  Thereafter, the pressing mechanism unit 14 is controlled by a signal output from the control unit 15 to raise the motor 13, and the jig 1 is separated from the metal plate 30 as shown in FIG. Thereby, a boss 31 having a shape that follows the shape of the groove 1 b of the jig 1 is formed on the surface of the metal plate 30. If necessary, the movement of the XY table 11 and the vertical movement by the pressing mechanism unit 14 are repeated to form bosses 31 at a plurality of locations on the metal plate 30, respectively.

  In this embodiment, since the metal in the metal plate 30 is plastically flowed to form the boss 31, the boss 31 is formed between the metal plate and the boss as compared with the case where the boss is joined to the metal plate by welding or pressure welding. High mechanical strength. In addition, as described above, according to the present embodiment, the occurrence of a depression on the outer surface of the metal plate 30 can be suppressed, and thus an electronic device that does not require (or is simple) a post-processing step and has a beautiful appearance. The housing can be easily manufactured.

  Fig.5 (a) is a perspective view which shows an example of the boss | hub formed by the above-mentioned metal processing method, FIG.5 (b) is the sectional drawing similarly.

  The boss 31 formed by the above-described method has a cylindrical shape that follows the shape of the groove 1b of the boss forming jig 1 as shown in FIGS. Further, around the boss 31, a concave portion 31 a having a shape that follows the processed surface 1 a of the jig 1 is formed. An amount of metal corresponding to the recess 31 a enters the groove 1 b of the jig 1 to form the boss 31.

  On the outer periphery of the recess 31a, a burr 31d is generated by the metal pushed out of the jig 1. However, in the present embodiment, as described above, since the amount of metal pushed out to the outside of the jig 1 is small, the height of the burr 31d is low, and there is no problem. If necessary, the burr 31d can be easily removed by polishing or the like.

  Hereinafter, a result of determining suitability when a boss is formed on a metal plate by the metal processing method according to the present embodiment and used as a casing of an electronic device will be described in comparison with a comparative example.

As the jigs of Examples 1 to 3, the radius of curvature R inside the protrusion 1c shown in FIG. 2 is about 0.3 mm (Example 1), about 0.5 mm (Example 2), and about 1 mm (Example 3). Jigs were prepared. In addition, all the height H of the protrusion part 1c is about 0.3 mm. The inner diameter φ ₁ of the groove 1b is about 2.4 mm, the outer diameter φ ₂ is about 5.0 mm, the groove depth D is about 5.0 mm, and the outer diameter φ ₃ of the jig 1 is about 8 mm.

On the other hand, as a jig of a comparative example, as shown in FIG. 6, a jig similar to those of Examples 1 to 3 was prepared except that there was no protrusion at the edge of the processed surface. The inner diameter φ ₁ of the jig 1b of the comparative example is about 2.4 mm, the outer diameter φ ₂ is about 5.0 mm, the groove depth D is about 5.0 mm, and the outer diameter φ ₃ of the jig 1 is about 8 mm. It is.

  The jigs of Examples 1 to 3 and the comparative example are all made of stainless steel (SUS304). Further, a magnesium alloy (AZ31B) plate having a thickness of about 1.0 mm was used for the metal plate 30 to be processed, and the processed surface was previously degreased and cleaned.

  The jigs of Examples 1 to 3 and the comparative example were attached to the metal processing apparatus shown in FIG. 1, and bosses were formed on the surface of the metal plate. The rotation speed of the jig at this time was about 8000 rpm and the friction pressure was about 30 MPa, and the jig was pushed from the surface of the metal plate 30 to a depth of about 0.5 mm.

  As a result, in all the jigs of Examples 1 to 3 and the comparative example, a hollow cylindrical boss having a shape following the groove shape of the jig could be formed. When the metal plates on which the bosses were formed were observed, recesses (scratch marks) in the shape of the processed surface of the jig were found around the bosses.

Moreover, the height of a burr | flash and the depth of the hollow of a back surface were measured about each metal plate after forming a boss | hub using each jig of Examples 1-3 and a comparative example. The results are shown in Table 1 below. Further, a tapping test was conducted. That is, M3 screw processing was performed on the inner wall surface of the boss using a tap, and then screw tightening was repeated five times to examine whether the boss and the thread were damaged. The tightening torque of the screw was about 5 kgf / cm ² . The results are also shown in Table 1.

表１からわかるように、比較例の冶具を用いた場合はバリの高さが約０．５ｍｍであったのに対し、実施例１〜３の冶具を用いた場合はバリの高さが０．０２ｍｍ〜０．１ｍｍと低いものであった。また、比較例の冶具を用いた場合は金属板の裏面に深さが約０．２ｍｍの窪みが発生したのに対し、実施例１〜３の冶具では窪みの深さは０．０１ｍｍ〜０．０６ｍｍと極めて小さいものであった。これらの結果から、上述した技術の有用性が確認された。なお、タッピング試験では、実施例１〜及び比較例のいずれにおいても、ボス及びねじ山の破損はなかった。

As can be seen from Table 1, when the jig of the comparative example was used, the burr height was about 0.5 mm, whereas when the jigs of Examples 1 to 3 were used, the burr height was 0. It was as low as 0.02 mm to 0.1 mm. Further, when the jig of the comparative example was used, a pit having a depth of about 0.2 mm was generated on the back surface of the metal plate, whereas in the jigs of Examples 1 to 3, the dent depth was 0.01 mm to 0 mm. It was extremely small as 0.06 mm. From these results, the usefulness of the above-described technique was confirmed. In the tapping test, neither the boss nor the screw thread was damaged in any of Examples 1 and Comparative Example.

  7-9 is sectional drawing which shows the modification of a boss | hub formation jig.

  The boss forming jig 41 shown in FIG. 7A is different from the jig 1 shown in FIG. 2 in that the tip of the inner portion of the groove 1b is formed in a conical shape. By providing a weight-like portion at the center of the machining surface in this way, the metal is pushed down the groove 1b by the weight-like inclined surface as shown in FIG. 7B during machining. Thereby, it can prevent more reliably that a hollow is formed in the back surface side of the metal plate 30. FIG.

  In the boss forming jig 42 shown in FIG. 8, the cross-sectional shape of the protrusion 42a provided at the edge on the processed surface is a triangle. Moreover, in the boss | hub formation jig | tool 43 shown in FIG. 9, the cross-sectional shape of the protrusion part 43a provided in the edge part of the process surface is a rectangle. The protrusion provided at the edge of the processed surface only needs to function as a wall that pushes back the plastically flowing metal, and may have a shape as shown in FIGS.

  The following additional notes are disclosed with respect to the above embodiments.

(Appendix 1) A step of plastically flowing a metal by pressing the metal jig while rotating the processing jig;
And a step of causing the plastic fluidized metal to enter a groove provided on a surface of the processing jig in contact with the metal material to form a protrusion having a shape following the shape of the groove on the surface of the metal material. ,
A metal processing method comprising: a protruding portion protruding in a direction parallel to a rotation axis of the processing jig at an edge of the surface of the processing jig on the metal material side.

  (Supplementary note 2) The metal processing method according to supplementary note 1, wherein the metal material is a plate material.

  (Supplementary note 3) The metal processing method according to supplementary note 1 or 2, wherein the metal material is made of Mg (magnesium), Al (aluminum), Ti (titanium) or an alloy mainly composed of those metals. .

  (Additional remark 4) The metal processing method of any one of Additional remark 1 thru | or 3 characterized by the groove | channel provided in the said processing jig being an annular | circular shape.

  (Supplementary note 5) The metal processing method according to any one of supplementary notes 1 to 4, wherein the metal material is heated in advance to a temperature of 200 ° C or higher.

(Appendix 6) A boss forming jig for pressing a metal material while rotating it to form a protrusion on the metal material,
A machined surface in contact with the metal material;
A groove provided on the processed surface side;
A boss forming jig, comprising: a protrusion provided at an edge of the processed surface and protruding in a direction parallel to the rotation axis.

  (Supplementary note 7) The boss forming jig according to supplementary note 6, wherein the groove has an annular shape centering on the rotation axis.

  (Supplementary note 8) The boss forming jig according to supplementary note 7, wherein an inner side of the annular groove on the processed surface is conical.

  DESCRIPTION OF SYMBOLS 1,41,42,43 ... Boss formation jig, 1a ... Work surface, 1b ... Groove, 1c, 42a, 43a ... Projection part, 3, 31d ... Burr, 4 ... Indentation (sink) 10 ... Metal processing apparatus, 11 ... XY table, 12 ... chuck, 13 ... motor, 14 ... pressing mechanism part, 15 ... control part, 30 ... metal plate, 31 ... boss, 31a ... concave part.

Claims (6)

A process of plastically flowing the metal by pressing the processing jig against the metal material while rotating,
And a step of causing the plastic fluidized metal to enter a groove provided on a surface of the processing jig in contact with the metal material to form a protrusion having a shape following the shape of the groove on the surface of the metal material. ,
A metal processing method comprising: a protruding portion protruding in a direction parallel to a rotation axis of the processing jig at an edge of the surface of the processing jig on the metal material side.   The metal processing method according to claim 1, wherein the metal material is a plate material.   The metal processing method according to claim 1, wherein the metal material is made of Mg (magnesium), Al (aluminum), Ti (titanium), or an alloy containing such a metal as a main component.   The metal processing method according to claim 1, wherein the groove provided in the processing jig has an annular shape.   The metal processing method according to claim 1, wherein the metal material is heated in advance to a temperature of 200 ° C. or higher. It is a boss forming jig that forms a protrusion on the metal material by pressing while rotating the metal material,
A machined surface in contact with the metal material;
A groove provided on the processed surface side;
A boss forming jig, comprising: a protrusion provided at an edge of the processed surface and protruding in a direction parallel to the rotation axis.

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