JP4821978B2 - Press tool surface treatment method and press tool surface-treated by the method - Google Patents

Description

  The present invention relates to a surface treatment technique for a punching tool and other press tools, and more particularly to a surface treatment method capable of improving the wear resistance of a tool surface and a punching tool and other press tools whose surfaces are cured by the method. .

Press work is widely used for molding various parts, and various press working tools (hereinafter referred to as “press tools”) are used depending on the application. For example, when punching (drilling), which is a typical press work, is performed on a steel plate for automobile parts, a stick-shaped punching tool generally called a punch is used.
In the punching tool, at the time of processing, a part of the surface (for example, the tip of the stick-shaped portion) contacts the workpiece (workpiece) under high pressure or high speed conditions. In recent years, the thickness of workpieces (for example, steel plates) has been increasing, and in order to increase the life of tools used for punching such workpieces (workpieces), the workpiece contact surface of the tool It is required to improve physical strength, particularly wear resistance.
For this purpose, conventionally, for example, a process of forming a hard film made of titanium carbide, titanium nitride or the like on a workpiece contact surface of a tool by using an ion plating apparatus or the like ( Patent Document 1). However, such a film forming process is time-consuming and expensive, and applying such a film forming process to the tool could be a factor in increasing the cost of the entire press working.

Japanese Patent Laid-Open No. 11-156992

  Accordingly, the present invention provides a punching tool and other press tools (a press working die formed into a predetermined shape at a relatively low cost without performing a costly process such as the conventional hard film forming process. It is an object of the present invention to provide a surface treatment method capable of improving the wear resistance of the surface. Another object of the present invention is to provide a punching tool and other press tools which are surface-treated by such a method and have improved wear resistance.

The present invention provides a surface treatment method for a press tool. One surface treatment method provided by the present invention includes curing the surface of the press tool by projecting coal ash onto at least the surface of the portion where friction occurs during pressing. Furthermore, in the present invention, fly ash having an average particle size adjusted to 20 μm or less is used as the coal ash.
The present inventor can easily improve the wear resistance by curing the surface of the press tool at high speed by projecting low-cost, relatively soft inorganic fine particles called fly ash onto the surface of the press tool. As a result, the present invention has been completed.

In the press tool surface treatment method disclosed herein, the surface of the press tool (typically, including injection and including the same applies hereinafter) treatment using coal ash (fly ash) of an appropriate particle size (typically). Improves the surface of parts that require high wear resistance in order to come into contact with the workpiece during pressing. Typically, in addition to being able to harden the tool surface by the impact of coal ash (fly ash) , a microscopic dimple (dimple) that promotes the retention of lubricating oil or the like is formed on the surface to increase wear resistance. It can improve. Preferably, coal ash (fly ash) is projected so that a hardened layer having a thickness of at least 5 μm is formed on the surface.
According to the surface treatment method of the present invention, a press tool having excellent wear resistance and a long life can be produced at low cost by using inexpensive coal ash (fly ash) as a material. In the surface treatment method of the present invention, a fly ash which is a spherical fine particle is projected onto the surface of the press tool, thereby forming a substantially uniform modified surface (cured layer) over the entire projection surface. Can do. Further, by using fly ash having an average particle size adjusted to 20 μm or less (typically classified), a punching tool or other press tool having a surface that is homogeneous and particularly excellent in wear resistance is manufactured. be able to.
Therefore, this invention provides the press tool which has the surface hardened | cured by the surface treatment method of either aspect disclosed here as another side surface. In a preferred embodiment of the press tool provided by the present invention, a wear-resistant hard coating comprising a fly ash deposit containing at least calcium oxide derived from fly ash on a surface cured by the surface treatment method disclosed herein. It is formed.

According to the surface treatment method disclosed herein, the wear resistance of a metal press tool can be improved without performing a conventional costly film formation treatment. The surface treatment method of the present invention having such an operational effect is a punching tool used in punching (punching) press work in which particularly high friction occurs on the contact surface with the workpiece during use, such as a punch (upper die). Or particularly useful for dies (lower molds).
Accordingly, a preferred aspect of the surface treatment method provided by the present invention is that a punching tool (typically a punch) which is a typical example of a press tool is subjected to friction due to contact with a workpiece at least during pressing. It is a punching tool surface treatment method including hardening the surface by projecting coal ash (fly ash) onto the surface of the portion where the above occurs. Moreover, the punching tool (punch etc.) which has the surface hardened | cured by such a surface treatment method is provided.

Preferably, wherein a portion of the components of the projected coal ash (fly ash) is projected onto the surface of該石ash (fly ash) with a pressure which can be attached to the surface of the tool.
According to the surface treatment method of this aspect, it is possible to realize surface modification that cannot be obtained by projection treatment (for example, air blasting) using conventional hard fine particles (for example, iron-based projection material). That is, in addition to be obtained by curing the tool surface by the impact of coal ash (fly ash), the components of the projected coal ash coal ash by (fly ash) is crushed by the tool surface (fly ash) ( Part of silica (alumina, ferric oxide, magnesium oxide, calcium oxide, etc.) (for example, calcium oxide) can adhere to the tool surface, and an abrasion-resistant hard coating composed of the deposit can be formed. Thereby, it is possible to manufacture a long-life punching tool and other press tools that are particularly excellent in wear resistance.

Also, preferably, especially, fly ash used in the projection is characterized in that a fly ash more than a diameter of 45μm is adjusted to below 40 wt%. In the press tool surface treatment method disclosed here, as described above, fly ash having a small variation in particle size (that is, a narrow particle size distribution) can be preferably used.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, matters (for example, the type and material of the press tool) other than the matters specifically mentioned in the present specification (for example, the properties of the coal ash to be used and the projection treatment conditions) and the matters necessary for carrying out the present invention are as follows: It can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  Examples of the press tool to which the surface treatment method of the present invention can be applied include press tools of various uses and forms. Particularly suitable are punch tools such as punches and dies used for punching. For example, a hardened layer can be formed at the tip of a cylindrical type or other long stick-shaped punch (that is, a work portion for punching a workpiece), thereby improving wear resistance. Moreover, the material of a press tool should just be a material which can form a hardened layer by projecting coal ash, and is not specifically limited. General die steel and high-speed steel, such as cold tool alloy tool steel (typically SKD11 and its improved steel), high speed tool steel (typically SKH51 and its improved steel) are the surfaces of the present invention. It is a preferable steel type for applying the treatment method.

  The coal ash used in the surface treatment method of the present invention is not particularly limited in its properties as long as it is suitable for use as a projection material. For example, clinker ash (or cinder ash) that has been appropriately pulverized and classified and adjusted in particle size may be used. The use of fly ash is preferred for the practice of the present invention. In particular, the raw powder is classified and the particle size is adjusted. A fly ash having an average particle size of 20 μm or less, for example, particles having a diameter of 45 μm or more classified from raw powder by a method such as airflow classification is 40% by mass or less (particularly preferably 10% by mass or less). A fly ash having a small variation (that is, a narrow particle size distribution) can be preferably used. In particular, fly ash having a narrow particle size distribution with an average particle size of 10 μm or less is preferred.

The conditions for performing projection (including injection) using coal ash (typically fly ash) as described above may be adjusted as appropriate depending on the press tool to be surface-treated and the properties of the coal ash used. It is not limited. It is preferable to project at such a pressure that a part of the component of the coal ash that has been projected and collided with the surface of the press tool can adhere to the surface of the tool.
For example, in the case of a punching tool made of general die steel (punch, etc.), the projected pressure of coal ash, for example, the radiating fluid in the case of air blast (typically air or inert such as nitrogen, argon, etc.) The pressure of the gas) is suitably about 0.1 MPa to 2 MPa, preferably about 0.1 to 1.5 MPa, particularly preferably about 0.5 to 1 MPa.

The means for projecting is not particularly limited as long as the above conditions can be satisfied, but as shown schematically in FIG. 1, a device for performing general sandblasting, shot blasting or air blasting (blasting device) 20 may be used. The projection (blast) time of the coal ash (typically fly ash) P is not particularly limited, but when a general die steel tool (here, a cylindrical punch) 10 such as SKD11 is used as a processing target, it is 0. A projection of about 1 to several tens of seconds (typically about 1 to 10 seconds) may be performed at a pressure of about 1 to 1.5 MPa.
As a result, as schematically shown in FIG. 1 and FIG. 2 which is a cross-sectional view of the projection site, the tool (punch) 10 directly contacts with the workpiece (ie, punching of the workpiece such as a plate). A desired hardened layer 13 can be formed on the surface of the tip portion 12 which is a work site used). Preferably, the coal ash P is projected so that a hardened layer 13 having a thickness of at least 5 μm is formed. As in the case of conventional general blasting, the projected coal ash P can be easily recovered by equipping the blasting device 20 with an appropriate dust collecting device (dust collecting device).
Thus, according to the surface treatment method of the present invention, a press tool can be obtained by using a general and simple blasting apparatus configuration and coal ash that can be obtained at a low cost without performing a complicated and expensive hard film forming treatment. It is possible to improve the wear resistance.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not intended to be limited to those shown in the examples.
As Example 1, a punch made of SKD11 as shown in FIG. 1 (length: 7 cm, main body diameter: 1 cm, main body tip working part length: 2 cm, diameter: 0.8 cm directly used for punching) A fly ash (obtained from the Japan Powder Industrial Technology Association) having a particle size distribution with an average particle size of about 7 μm obtained by classifying the raw powder at the tip of the product is commercially available. Fuji Seisakusho: Projected (sprayed) using the brand name Pneumatic Blaster DPV-1).
Specifically, fly ash is projected for about 10 seconds from the nozzle of the apparatus (diameter of about 1 mm) at a projection pressure (air pressurization pressure in this embodiment) of 0.7 MPa so as to be substantially uniform over the entire surface of the punch tip ( Jetted). The distance from the nozzle tip to the substrate surface was 10 to 50 mm.
As comparative examples, a commercially available silicon carbide (SiC) powder having an average particle diameter of about 4 μm (Comparative Example 1) and a commercially available tungsten carbide (WC) powder having an average particle diameter of about 8.7 μm (Comparative Example 2). The projection process was performed under the same conditions.

  Next, a punching test was performed using the punches obtained in Example 1, Comparative Example 1, and Comparative Example 2, respectively. That is, a punch subjected to the projection treatment is mounted as an upper mold of a die press for a practical machine (product of Fujii Kogyo Co., Ltd.), and a 2 mm-thick steel plate made of SS steel, which is rolled steel, is processed ( Used as a workpiece), and punching and stamping with a single punch was continuously performed for a total of 9000 times. As Comparative Example 3, the same continuous punching process was performed using the punch having the same shape without the projection process.

After the continuous punching is completed, the punching boundary between the punch tip and the side of the punch (that is, the boundary between the part that contacts the workpiece and causes friction when punching the workpiece side and the part that does not contact the workpiece) is observed with an optical microscope. did.
That is, FIG. 3 shows a state after 9000 times of continuous punching of the punch (Example 1) subjected to fly ash projection processing. FIG. 4 shows a state after 9000 times of continuous punching of the punch subjected to the SiC powder projection process (Comparative Example 1). FIG. 5 shows a state after 9000 times of continuous punching of the punch subjected to the WC powder projection treatment (Comparative Example 2). FIG. 6 shows a state after 1920 times of punching (Comparative Example 3) without any projection processing.
(B) of each figure is a stereomicrograph showing the state in the vicinity of the punch tip, (A) is an optical micrograph showing an enlarged surface of the punch tip, and (C) shows the punching boundary on the side of the punch. It is an optical microscope photograph which expands and shows.

Furthermore, the surface and cross section of the punch tip after the end of continuous punching were observed with an SEM. That is, FIGS. 7A and 7B are SEM images of the punch tip surface after 9000 consecutive punches of the fly ash projected punch (Example 1). 8A and 8B are SEM images of the cross-section of the punch tip after 9000 times of continuous punching of the fly ash projected punch (Example 1).
FIGS. 9A and 9B are SEM images of the punch tip surface after 9000 times of continuous punching of the punch subjected to the SiC powder projection process (Comparative Example 1). 10A and 10B are SEM images of the cross-section of the punch tip after 9000 times of continuous punching of the punch subjected to the SiC powder projection process (Comparative Example 1).
(A) and (B) of FIG. 11 are SEM images of the punch tip surface after continuous punching 9000 times of a punch that has been subjected to WC powder projection processing (Comparative Example 2). FIGS. 12A and 12B are SEM images of a cross-section of the punch tip after continuous punching 9000 times of the punch subjected to the WC powder projection process (Comparative Example 2).

As is apparent from the results shown in FIGS. 3 to 12, in the punch of Comparative Example 3 that has not been subjected to projection, many streak marks are recognized in the major axis direction at the workpiece contact portion on the side of the punch ((A) in FIG. 6) reference). That is, the punch was severely damaged after 1920 times of continuous punching, and further use was impossible.
Further, in the punch of Comparative Example 1 that has been subjected to the SiC powder projection treatment and the punch of Comparative Example 2 that has been subjected to the WC powder projection treatment, the hardened layer at the tip of the punch is remarkably removed after 9000 times of continuous punching. In the punch No. 1, the tip portion was severely damaged, and the appearance of a base material and a partial defect were observed (see FIGS. 4A and 9).
On the other hand, in the punch according to Example 1 in which fly ash was projected, damage as much as the punch of each comparative example was not recognized, and the hardened layer was relatively held at the punch tip. This confirms that the wear resistance of a press tool such as a punch can be easily improved by the surface treatment method of the present invention, and that the service life of these press tools can be increased.

As described above, according to the present invention, wear resistance is improved, and a long tool punching tool and other press tools can be provided. Moreover, since the projection material is coal ash such as fly ash, the surface treatment of the press tool can be performed at low cost.
Moreover, this invention pioneered the new use of coal ash and has contributed to resource recycling.

It is explanatory drawing which shows typically the procedure of the surface treatment method of this invention. It is sectional drawing which shows typically the state of the press tool (punch) processed by the surface treatment method of this invention. It is a microscope picture which shows the state after the continuous punching process use of the punch which projected fly ash, (B) is a photograph which shows the state of punch tip vicinity, (A) is a photograph which expands and shows the punch tip surface. Yes, (C) is an enlarged photograph showing the punching boundary on the side of the punch. It is a microscope picture which shows the state after the continuous punching process use of the punch which projected SiC powder, (B) is a photograph which shows the state of punch tip vicinity, (A) is a photograph which expands and shows the punch tip surface. Yes, (C) is an enlarged photograph showing the punching boundary on the side of the punch. It is a microscope picture which shows the state after the continuous punching process use of the punch which projected WC powder, (B) is a photograph which shows the state of punch tip vicinity, (A) is a photograph which expands and shows the punch tip surface. Yes, (C) is an enlarged photograph showing the punching boundary on the side of the punch. It is a microscope picture which shows the state after continuous punching processing use of the punch which has not performed the powder projection process, (B) is a photograph which shows the state of punch tip vicinity, (A) expands and shows a punch tip surface. It is a photograph and (C) is a photograph which expands and shows the punching process boundary part of a punch side surface. It is a SEM photograph which shows the state after continuous punching processing use of the punch which projected fly ash, (A) is a SEM image of a punch tip surface, and (B) is an image which expanded a part of (A). . It is a SEM photograph which shows the state after use of continuous punching processing of the punch which projected fly ash, (A) is a SEM image of the section of a punch tip, and (B) is an image which expanded a part of (A). is there. It is a SEM photograph which shows the state after use of continuous punching processing of the punch which projected SiC powder, (A) is a SEM image of a punch tip surface, and (B) is an image which expanded a part of (A). . It is a SEM photograph which shows the state after use of continuous punching processing of the punch which projected SiC powder, (A) is a SEM image of the section of a punch tip, and (B) is an image which expanded a part of (A). is there. It is a SEM photograph which shows the state after continuous punching processing use of the punch which projected WC powder, (A) is a SEM image of a punch tip surface, and (B) is an image which expanded a part of (A). . It is a SEM photograph which shows the state after continuous punching processing use of the punch which projected WC powder, (A) is a SEM image of the section of a punch tip, and (B) is an image which expanded a part of (A). is there.

Explanation of symbols

10 Press tool (punch)
12 Tip 13 Hardened layer 20 Blasting device

Claims (5)

Curing the surface of the press tool by projecting fly ash having an average particle size adjusted to 20 μm or less onto at least the surface of the portion where friction occurs during pressing,
A surface treatment method for a press tool. The surface treatment method according to claim 1, wherein the fly ash is projected so that a hardened layer having a thickness of at least 5 μm is formed on the surface. The surface treatment method according to claim 2, wherein the fly ash is projected onto the surface at a pressure at which a part of the component of the projected fly ash can adhere to the surface. The surface treatment method according to claim 1, wherein a fly ash used for the projection is a fly ash having a diameter of 45 μm or more adjusted to 40% by mass or less . A press tool having a surface hardened by the surface treatment method according to any one of claims 1 to 4, wherein the wear-resistant hard coating comprises a fly ash deposit containing at least calcium oxide derived from fly ash on the surface. A press tool characterized in that is formed .