JP2014018801A - Hole piercing method, method for manufacturing structure with hole, and structure with hole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a hole piercing method that facilitates hole piercing using a hot press; a method for manufacturing a structure with a hole; and the structure with the hole.SOLUTION: A hot press forming method includes: a heating step S1 of heating a workpiece W; a cutting/machining step S4 of piercing a hole through the workpiece W using a piercing blade 24a; a recess machining step S5 of forming a recess C for enlarging a diameter of the hole H around the hole H opened in the cutting/machining step S4; and a cooling step S6 of cooling the workpiece W. In the method, an enlarged amount of the diameter of the hole H by the recess C formed in the recess machining step S5 is larger than a reduced amount of the diameter caused in the cooling step S6.

Description

  The present invention relates to a drilling method using a hot press in which a heated structure is pressed and then cooled and quenched, a method for manufacturing a structure with holes, and a structure with holes.

  A technique for manufacturing a structure using a hot press is known. In the hot pressing, the structure is first heated to about 1000 ° C., and the heated structure is pressed, and then the structure is cooled to change the steel sheet structure from the austenite structure during heating to martensite. Quenching that transforms the structure is performed, and the pressed structure is formed with high hardness.

Conventionally, a technique for extending the life of a tool for drilling or trimming when a structure such as a vehicle body part is manufactured using a hot press has been disclosed (for example, see Patent Document 1).
In the technique disclosed in Patent Document 1, when a heated structure is formed by a mold, the structure is processed by a tool at the same time.
According to this technique, since the structure is processed with the tool before the structure is formed with high hardness by quenching by cooling, the burden on the tool can be reduced and the life of the tool can be extended.

JP 2005-248253 A

  However, even with the technique disclosed in Patent Document 1, it is not easy to make holes in the structure.

  FIG. 5 is a diagram showing a drilling method using a hot press according to the prior art and its problems. (A) shows a drilling process and (b) shows a problem.

As shown in FIG. 5A, when the heated structure W101 is placed on the lower mold 202 and press molding is performed by moving the upper mold 201 to the bottom dead center, the upper structure 201 is integrated with the upper mold 201. The structure W101 is drilled by the configured piercing blade 301.
After the hole H401 is opened in the structure W101 by the piercing blade 301, the upper mold 201 may be held at the bottom dead center in order to prevent the structure W101 from being deformed due to shrinkage caused by a temperature drop.

However, when the structure W101 is cooled and quenched with the upper mold 201 held at the bottom dead center, that is, with the piercing blade 301 inserted into the hole H401, the structure W101 contracts and the hole The diameter of H401 is reduced, and as shown in FIG. 5B, the piercing blade 301 is restrained by the reduced diameter hole H401.
For this reason, it is difficult to separate the piercing blade 301 constrained by the reduced diameter hole H401 from the structure W101.

  The present invention is for solving the above-mentioned problems, and the object thereof is to provide a drilling method for easily performing a drilling process using a hot press, a method for manufacturing a structure having holes, and a hole. It is to provide a structure.

  (1) A drilling method using a hot press, in which a punching process (for example, a piercing blade 24a described later) is performed on a structure (for example, a workpiece W described later) by a drilling process (for example, An uneven portion (for example, a recess C described later) for expanding the diameter of the hole is formed around a hole (for example, a hole H described later) opened in the hole forming step of the structure, which will be described later. A drilling method characterized by including a concave / convex processing step (for example, a concave processing step S5 described later) and a cooling step (for example, a cooling step S6 described later) for cooling the structure.

  According to the invention of (1), since the diameter of the hole is increased by a minute amount by forming an uneven portion around the hole, the hole is smaller than the diameter of the cutting blade even if the structure cooled in the cooling process contracts. The diameter is not reduced. Therefore, even if the cooling process is performed with the cutting blade inserted into the hole after drilling, the cutting blade is not constrained by the hole, and the cutting blade can be easily formed from a structure with high hardness. Can be separated. Therefore, a hole punching process can be easily performed using a hot press.

  (2) The hole drilling method according to (1), wherein an amount of diameter expansion of the hole by the uneven portion formed by the unevenness processing step is larger than an amount of diameter reduction by the cooling step.

  According to the invention of (2), since the diameter of the hole due to the uneven portion is larger than the diameter reduced by the cooling process, the diameter of the hole is expanded even if the structure cooled by the cooling process contracts. be able to.

  (3) (1) or (2), wherein the diameter expansion amount of the hole by the uneven portion formed by the unevenness processing step is larger in a direction in which the diameter reduction amount in the radial direction by the cooling step is larger. The drilling method described.

  According to the invention of (3), since the diameter expansion amount of the hole due to the concavo-convex portion is larger as the diameter reduction amount in the radial direction by the cooling process is larger, even if the diameter reduction amount in the radial direction by the cooling process is different. The shape of the hole is not greatly deformed from the shape when it is opened in the hole making process.

  (4) A method of manufacturing a structure (for example, a work W described later) provided with a hole (for example, a hole H described later) manufactured using a hot press, the heating step for heating the structure ( For example, a heating step S1) to be described later, a drilling step (for example, a cutting step S4 to be described later) for punching the structure with a cutting blade (for example, a piercing blade 24a to be described later), and a periphery of the hole An uneven processing step (for example, a recess processing step S5 described later) for forming an uneven portion (for example, a recess C described later) for expanding the diameter of the hole formed in the hole forming step of the structure, and the cutting blade A cooling step (for example, cooling step S6 to be described later) for cooling the structure in a state of being inserted into the hole, and the diameter expansion amount of the hole by the uneven portion formed by the uneven processing step is It is larger than the diameter reduction by the cooling process. Method for producing a structure with a hole, characterized.

  According to the invention of (4), the diameter of the hole is increased by a minute amount by forming an uneven part in which the diameter of the hole is larger than the amount of diameter reduction by the cooling process around the hole. Even if the structure contracts, the diameter of the hole can be increased. Therefore, even if the cutting blade is inserted into the hole after the drilling process and the cooling process is performed, the cutting blade is not restrained by the expanded diameter hole, and the cutting blade is formed with high hardness. It can be easily separated from the body. Therefore, a hole punching process can be easily performed using a hot press.

  (5) A heating process for heating the structure in the hot press, which is a structure (for example, a work W described later) provided with a hole (for example, a hole H described later) manufactured using a hot press. With a cutting blade (for example, a piercing blade 24a, which will be described later) formed after the cooling process (for example, a cooling step S6, which will be described later) after the heating process (for example, a heating step S1 which will be described later). A structure provided with a hole, comprising: a hole formed by drilling a hole; and a concavo-convex part (for example, a concave part C described later) for expanding the diameter of the hole around the hole.

  According to invention of (5), there exists an effect similar to invention of (1).

  (6) A heating process for heating the structure in the hot press, which is a structure (for example, a work W described later) provided with a hole (for example, a hole H described later) manufactured using a hot press. Cooling that is formed by drilling with a cutting blade (for example, a piercing blade 24a described later) after (for example, heating step S1 described later), and cools the structure in a state where the cutting blade is inserted into the hole. A hole that undergoes a process (for example, cooling process S6 described later), and an uneven part that is formed around the hole after the drilling process, and expands the hole by a larger diameter than the diameter reduced by the cooling process. (For example, a concave portion C described later), and a structure including a hole.

  According to the invention of (6), the same effect as the invention of (4) is produced.

  ADVANTAGE OF THE INVENTION According to this invention, the drilling method which performs a drilling process easily using a hot press, the manufacturing method of the structure provided with the hole, and the structure provided with the hole can be provided.

It is a figure which shows each process in the hot press molding method which concerns on embodiment of this invention. It is process drawing of the hot press molding method which concerns on the said embodiment. It is a hole periphery enlarged view of the workpiece | work in which the recessed part which concerns on the said embodiment was formed. It is a hole periphery enlarged view of the workpiece | work manufactured by the hot press molding method which concerns on the said embodiment. It is a figure which shows the drilling method using the hot press of a prior art, and its problem.

Embodiments of the present invention will be described below with reference to the drawings.
First, the metal mold | die 1 used for the hot press molding method is demonstrated.
FIG. 1 is a diagram showing each step in a hot press molding method according to an embodiment of the present invention, where (a) is a placement step, (b) is a foam molding step, (c) is a cutting step, d) shows a recessed part processing process, respectively.

  The workpiece W formed by the hot press forming method is a structure such as a vehicle body part made of a high-tensile steel plate, and has a high hardness structure having high tensile strength after press forming by the hot press forming method. Manufactured to the body.

  A mold 1 used in the hot press molding method includes an upper mold 2 and a lower mold 3 as shown in FIG. The upper die 2 is a movable die that descends during pressing, and the lower die 3 is a fixed die.

  The upper mold 2 includes a pad 21 having an upper molding surface 21a that forms a substantially frustoconical form on the workpiece W in cooperation with a lower molding surface 3a (described later) of the lower mold 3. The pad 21 is attached to the upper mold 2 via an elastic body 22. The elastic body 22 contracts after a foam molding process, which will be described later, to bring the pad 21 close to the upper mold 2.

  The upper die 2 includes an upper trim portion 23 in a peripheral region of the pad 21 where foam molding is performed, and includes a piercing portion 24 and a score punch portion 25 at a substantially central portion of the pad 21.

The upper trim portion 23 is disposed in the peripheral region of the pad 21 and is integrally attached to the upper mold 2. The upper trim portion 23 has an upper trim blade 23a for cutting the end portion of the workpiece W.
The upper trim blade 23a cooperates with the lower trim blade 31a and cuts with the end portion of the workpiece W interposed therebetween.

The pierce portion 24 is disposed at the center of a hole portion 21 b provided at a substantially central portion of the pad 21 and is integrally attached to the upper mold 2. The piercing portion 24 has a piercing blade 24a for drilling a circular hole H (see FIG. 3) having a diameter φA in the work W.
The piercing blade 24a is a circular end face, and opens a hole H in the workpiece W when being accommodated in a hole 33 of the lower mold 3 described later.

The score punch portion 25 is disposed in a substantially annular shape around the piercing portion 24 in a hole portion 21 b provided in a substantially central portion of the pad 21, and is integrally attached to the upper mold 2. The score punch unit 25 includes a score punch 25a that forms a later-described recess C in the workpiece W.
The score punch 25a may be a hemispherical convex portion formed by interspersing dents around the hole H of the workpiece W.

The upper trim portion 23 and the piercing portion 24 are formed so that the upper trim blade 23a and the piercing blade 24a cut the workpiece W before the upper die 2 is lowered and the score punch 25a forms the recess C in the workpiece W. It is configured. The cutting process by the upper trim blade 23a and the cutting process by the piercing blade 24a may be configured to be performed at substantially the same timing.
In other words, the upper trim portion 23 protrudes downward from the piercing portion 24, but at a position where the workpiece W is cut by the upper trim blade 23a at substantially the same timing as the cutting of the workpiece W by the piercing blade 24a. It may be arranged.

  The piercing portion 24 protrudes below the score punch portion 25 in order to cut the workpiece W by the piercing blade 24a before the score punch portion 25 forms the recess C in the workpiece W by the score punch 25a. .

  The score punch unit 25 cuts the workpiece W with the piercing blade 24a to form the hole H, and then forms the recess C around the hole H of the workpiece W at the timing when the upper mold 2 reaches the bottom dead center. Is arranged.

  The lower mold 3 is fixed to the floor surface, and has a lower molding surface 3a that forms the workpiece W in cooperation with the upper molding surface 21a of the pad 21.

  The lower die 3 includes a lower trim portion 31 below the pad 21, a tray 32 below the upper trim portion 23, a hole 33 below the piercing portion 24, and a recess 34 below the score punch portion 25. Is provided.

  The lower trim portion 31 is disposed inside the mold 1 with respect to the upper trim portion 23 and is integrally attached to the lower die 3. The lower trim portion 31 has a lower trim blade 31a that cuts an end portion of the workpiece W with the workpiece W interposed therebetween in cooperation with the upper trim blade 23a.

  The tray 32 receives a cut piece E of the workpiece W dropped by being sandwiched and cut between the upper and lower trim blades 23a and 31a.

  The hole 33 allows the hole piece D of the workpiece W that has been drilled and dropped by the piercing blade 24a to flow downward.

  The recess 34 may be a hemispherical recess, and is positioned around the hole 33 of the lower molding surface 3a of the lower mold 3 at a position where the tip of the score punch 25a is pushed when the score punch 25a forms the recess C. It may be provided.

  Since the score punch 25a is provided on the upper mold 2 and the recess 34 is provided on the lower molding surface 3a of the lower mold 3, and no protrusion is provided on the lower molding surface 3a, the workpiece placed on the recess 34 W is held on the lower molding surface 3a of the lower mold 3 without being lifted. For this reason, in the foam forming step S3 and the cutting step S4, which will be described later, a shift due to the lifting of the workpiece W does not occur, and the product accuracy of the workpiece W does not deteriorate.

Next, the hot press molding method according to this embodiment will be described.
FIG. 2 is a process diagram of the hot press molding method according to the present embodiment.

(Heating step S1)
In the hot press molding method, first, the workpiece W is heated to about 1000 ° C. or the like.

(Installation process S2)
Then, as shown in FIG. 1A, the heated workpiece W is placed at a predetermined position on the lower molding surface 3a of the lower mold 3 in a state where the upper mold 2 is lifted to the top dead center and the mold is opened. .

(Form forming step S3)
Next, the upper die 2 is lowered from the top dead center, and the pad 21 of the upper die 2 is brought into contact with the workpiece W placed on the lower die 3 as shown in FIG. Is pressed by the pad 21 and the lower mold 3 to form the workpiece W in accordance with the upper molding surface 21a and the lower molding surface 3a.

(Cutting process S4)
When the upper die 2 is further lowered, as shown in FIG. 1C, the elastic body 22 contracts in a state where the contact with the work W by the pad 21 is maintained, and the upper trim portion of the upper die 2 is contracted. 23, the upper trim blade 23a is brought into contact with the workpiece W, and cutting processing is performed in which the upper and lower trim blades 23a and 31a sandwich the end portion of the workpiece W and cut.
At almost the same time, the piercing blade 24a of the piercing portion 24 of the upper mold 2 is brought into contact with the workpiece W, and a drilling process is performed in which a hole H having a diameter φA is formed in the workpiece W by the piercing blade 24a.

(Concavity processing step S5)
Further, the upper die 2 is lowered to the bottom dead center, and the score punch 25a of the score punch portion 25 of the upper die 2 is brought into contact with the workpiece W as shown in FIG. The concave portion C is formed by pressing the portion against the concave portion 34 of the lower mold 3.

Here, the workpiece | work W in which the recessed part C was formed is demonstrated.
3A and 3B are enlarged views around the hole H of the workpiece W in which the recess C according to the present embodiment is formed. FIG. 3A is a perspective view and FIG. 3B is a cross-sectional view.
As shown in FIG. 3, the recesses C are formed around the holes H cut by the piercing blades 24 a of the workpiece W.

The concave portion C is for drawing the meat around the hole H of the broken line diameter φA of the workpiece W into the concave portion C on the outer diameter side of the hole H and expanding the hole H by a minute amount to the diameter φB of the solid line illustrated. The diameter expansion amount of the hole H by the recess C is set larger than the diameter reduction amount by the cooling step S6.
Moreover, it is preferable that more concave portions C are formed in the direction in which the amount of diameter reduction in the radial direction in the cooling step S6 is larger. That is, when the amount of diameter reduction in the radial direction by the cooling step S6 of the hole H is different, such as when the position of the hole H in the work W is not the substantially central portion but close to the bent portion of the work W, It is preferable that the diameter expansion amount is set to be larger as the direction in which the diameter reduction in the radial direction in the cooling step S6 is larger.
The shape of the hole H having a diameter φB expanded by the recess C is such that the larger the amount of the recess C, the larger the amount of diameter expansion in the radial direction, and the recess C forms the hole H in a desired shape after the cooling step S6 ( For example, they are arranged so as to have a circular shape with a diameter φA that is opened in the cutting process S4 and that is only one size larger and does not deform significantly.

Next, it returns to description of the process of the hot press molding method shown in FIG.
(Cooling step S6)
After the recess C is processed, the workpiece W is cooled together with the mold 1 in a state where the upper die 2 is maintained at the bottom dead center in order to prevent the deformation of the workpiece W due to shrinkage caused by a temperature drop.
When the workpiece W is contracted by this cooling, the hole H having a diameter φB that has been expanded according to the radial expansion amount by the recess C is reduced according to the radial reduction amount, and at least from the diameter φA. Is formed to have a substantially substantially circular shape diameter φC (see FIG. 4A).

  At this time, the piercing blade 24a inserted into the hole H of the workpiece W is expanded by the recess C against the amount of diameter reduction by the cooling step S6 (diameter φC> diameter φA). Even if the diameter of the hole H is reduced by the shrinkage of W, the hole H is not restricted and can be easily separated from the workpiece W.

  Then, the upper mold 2 is opened to the top dead center, the piercing blade 24a is pulled out without contacting the hole H having the diameter φC, and the workpiece W is taken out from the mold 1.

Next, the workpiece | work W manufactured by the hot press molding method is demonstrated.
FIG. 4A is an enlarged view around the hole H of the workpiece W manufactured by the hot press molding method according to the present embodiment.
As shown in FIG. 4A, the workpiece W having the holes H manufactured by the hot press forming method is formed by drilling with the piercing blade 24a in the cutting process S4 after the heating process S1. In the state where the piercing blade 24a is inserted into the hole H, the hole H is formed around the hole H in the cooling step S6 for cooling the workpiece W and in the recess processing step S5 after the drilling process. And a recess C that expands the hole by a diameter expansion amount larger than the diameter amount.

Then, as shown in FIG. 4 (a), the hole diameter drilled by the piercing blade 24a and the outer diameter of the piercing blade 24a substantially equal to the hole diameter are indicated by the broken line diameter φA, and the hole diameter expanded by the recess C is shown in FIG. If the diameter φB of the chain line and the hole diameter reduced by cooling are the diameter φC of the solid line in the figure, the relationship of diameter φB> diameter φC> diameter φA is established.
The relationship of diameter φB> diameter φC> diameter φA makes it easy to pull out the piercing blade 24a having the outer diameter of diameter φA from the hole H having the diameter φC in the work W formed with high hardness after the cooling step S6.

  According to the hot press molding method according to the present embodiment described above, the following effects are obtained.

  (1) Since the diameter of the hole H is increased by a minute amount by forming a recess C in which the diameter of the hole H is larger than the amount of diameter reduction in the cooling step S6 around the hole H, the hole H is cooled in the cooling step S6. Even if the workpiece W contracts, the hole H can be expanded (diameter φC> diameter φA). Therefore, even if the piercing blade 24a is inserted into the hole H after the perforating process and the cooling process S6 is performed, the piercing blade 24a is not restrained by the expanded hole H, and the piercing blade 24a has a high hardness. It can be easily separated from the workpiece W formed in the above. Therefore, it is possible to easily perform drilling in the hot press molding method.

  (2) Since the diameter expansion amount of the hole H by the recessed part C is larger than the diameter reduction amount by the cooling step S6, the hole H should be expanded even if the workpiece W cooled by the cooling step S6 contracts. Can do.

  (3) Since the diameter expansion amount of the hole H by the concave portion C is larger as the diameter reduction amount in the radial direction by the cooling step S6 is larger, the hole diameter is reduced even when the diameter reduction amount by the cooling step S6 is different. The shape of H is not greatly deformed from the shape when opened in the cutting step S4.

  Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the scope of the present invention.

  In the above embodiment, the concave portion C is formed around the hole H by the score punch 25a. However, the present invention is not limited to this, and the convex portion and the uneven portion may be formed as long as the diameter of the hole H is increased. Good.

  In the said embodiment, although the recessed part C was formed so that the amount of diameter reduction of radial direction by cooling process S6 was large, it is not limited to this, but the recessed part C is radial direction by cooling process S6. As shown in FIG. 4B, the smaller the amount of diameter reduction, the larger (the amount of processing or the processing area) may be formed, or more may be formed at the same time. That is, it is preferable that the diameter expansion amount of the hole H by the concave portion C is set to be larger as the diameter reduction amount in the radial direction by the cooling step S6 is larger.

  In the said embodiment, although the recessed part C was formed so that the amount of diameter reduction of radial direction by cooling process S6 was large, it is not limited to this, but the recessed part C is radial direction by cooling process S6. If the amount of diameter reduction is equal, as shown in FIG. 4 (c), a plurality of dots are scattered at equal intervals from the center of the hole H around the hole H, or as shown in FIG. 4 (d). It may be formed in an annular shape surrounding the periphery of the. In this case, the hole diameter can always be maintained in a perfect circular shape in each step of the hot press forming method, and the shape of the hole H after quenching can be easily formed in a desired perfect circular shape.

Moreover, in the said embodiment, although the timing of the cutting process of the edge part of the workpiece | work W by the upper and lower trim blades 23a and 31a and the timing of the drilling process of the workpiece | work W by the piercing blade 24a were substantially the same, It is not limited, and both processes may be performed at different timings.
Moreover, in the said embodiment, although foam shaping | molding and cutting were performed simultaneously, it is not restricted to this. The molding may be molding other than foam molding, such as drawing molding, and the molding and cutting may not be performed simultaneously.

H ... Hole C ... Concave processing (Uneven portion)
24a ... Piercing blade (cutting blade)
W ... Work (structure)
S1 ... heating process S4 ... cutting process (drilling process)
S5: Concave processing step (concave / convex processing step)
S6 ... Cooling process

Claims (6)

A drilling method using a hot press,
A drilling step of drilling a structure with a cutting blade;
A concavo-convex processing step for forming a concavo-convex portion for expanding the diameter of the hole around the hole formed in the hole-piercing step of the structure,
And a cooling step for cooling the structure.   2. The drilling method according to claim 1, wherein an amount of diameter expansion of the hole by the uneven portion formed by the unevenness processing step is larger than an amount of diameter reduction by the cooling step.   3. The drilling process according to claim 1, wherein an amount of diameter expansion of the hole by the uneven portion formed by the unevenness processing step is larger in a direction in which the amount of diameter reduction in the radial direction by the cooling step is larger. Method. A method of manufacturing a structure with holes manufactured using a hot press,
A heating step of heating the structure;
A drilling step of drilling the structure with a cutting blade;
A concavo-convex processing step for forming a concavo-convex portion for expanding the diameter of the hole formed in the perforating step of the structure around the hole,
A cooling step of cooling the structure with the cutting blade inserted into the hole,
A method for manufacturing a structure having holes, wherein the amount of diameter expansion of the hole by the uneven portion formed by the unevenness processing step is larger than the amount of diameter reduction by the cooling step. A structure with holes produced using a hot press,
A hole formed by drilling with a cutting blade after the heating step of heating the structure in a hot press and before the cooling step of cooling the structure, and the hole around the hole A structure provided with a hole, characterized by comprising an uneven portion for expanding the diameter. A structure with holes produced using a hot press,
A hole that is formed by drilling with a cutting blade after a heating step for heating the structure in a hot press, and undergoes a cooling step for cooling the structure with the cutting blade inserted into the hole;
A structure having a hole, comprising: an uneven portion that is formed around the hole after the drilling process and expands the hole by a diameter expansion amount larger than a diameter reduction amount by the cooling step. body.

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