JP7295537B2 - Powder adhesion suppression member and member surface treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a powder adhesion suppression member and a surface treatment method. More specifically, the present invention relates to a technique for suppressing adhesion of powder, particularly powder to which oil or moisture adheres, by, for example, forming unevenness on the surface with which the powder comes into contact.

Conventionally, edible powders such as wheat flour, cornstarch, potato starch, matcha powder, cocoa powder, powdered sugar, curry powder, consommé powder, and powders such as pharmaceutical powders (powder medicines) are separated by a stainless steel sieve (or Classification) treatment is carried out or handled using containment vessels such as hoppers and conveying components such as shooters and conveyors made of stainless steel.

These powders adhere to and grow on the surfaces of members such as sieves, storage containers, and conveying parts, and become relatively large lumps, causing problems such as poor discharge (hoppers) and clogging (sieves). This is one of the causes of lower production efficiency and an increase in defective products.

For this reason, the present inventors have repeatedly conducted various research and experiments, and based on the results, the present applicant et al. A fine particle peening treatment (WPC treatment (registered trademark)) is performed to randomly form an infinite number of fine irregularities on the surface of a member that comes into contact with powder (hereinafter also referred to as a powder contact member). proposed a technology that can suppress the adhesion of powder.

Japanese Patent No. 6416151

However, through various experiments, the present inventors have found that when the powder is fine (fine particles) and oil or moisture adheres to its surface (surroundings) (for powders that tend to aggregate and form lumps) confirmed that the technology described in Patent Document 1 does not sufficiently suppress adhesion of fine particles.

That is, as described in Patent Document 1, a fine particle peening treatment (WPC treatment (registered trademark)) is performed to form countless fine irregularities on the surface of a member that comes into contact with powder (hereinafter also referred to as a powder contact member). It has been found that by forming the particles randomly (randomly), it is possible to suppress adhesion to powder such as wheat flour.

However, as an example of the powder to be treated, curry powder and consommé powder containing oil and water, for example, do not come in contact with the powder on the surface of random irregularities formed by the conventional fine particle peening treatment. Experimental results were obtained that the effect of slipping on the contact surface of the member and adhesion suppression is small.

For example, typical examples include seasoning powders such as curry powder and consommé powder, powders of snacks, and other powders with oil or moisture attached (or containing oil or moisture) (aggregated into clumps). It is believed that the oil and water contained in the powder itself adheres to the surface of the powder contact member, resulting in extremely poor slipperiness.

As a result of detailed consideration of the experiment, the present inventors found that the consommé powder to which oil and moisture adhered had a relatively large particle size distribution, and had a particle size of 1 µm or less, and those with a particle size aggregated to 200 µm or more. was included, and it was confirmed that various shapes were included (Figs. 1 and 2).

On the other hand, by the fine particle peening treatment proposed in Patent Document 1, the size of the recess formed on the surface of the powder contact member is, for example, about φ5 to φ100 μm for the entrance diameter of the recess (opening diameter of the opening) and about φ100 μm for the depth. is about 0.5 to 3.0 μm.

For this reason, the inventors of the present invention have found that the concave shape of Patent Document 1 is effective for suppressing the adhesion of powder aggregated to a size of 200 μm or more, but it is effective for powder containing particles with a particle size of 1 μm or less. As a result, the entrance width (opening width) of the minute recesses formed by the conventional fine particle peening process is too large, and powder with a particle size of 1 μm or less is accommodated in the recesses of the minute recesses. It was considered that the phenomenon that the slipperiness of the powder on the surface of the contact member and the effect of suppressing adhesion of the powder was reduced was occurring.

For this reason, the present inventors produced a powder contact member having a surface with an inlet width (in the case of a circle) of 1 μm or less in micro recesses, corresponding to powder with a particle size of 1 μm or less. An experiment was conducted to suppress adhesion of powder of 1 μm or less. According to the experiment, a good adhesion suppression effect was obtained when individual powders were separated without containing oil or water. It was confirmed that the effect of suppressing adhesion cannot be sufficiently exhibited in the case of powder to which oil or water is adhered, and that the effect of suppressing adhesion is not sufficient in the case of powder aggregated to a size of 200 μm or more.

From this phenomenon, on the surface of random irregularities consisting of dimple-shaped recesses having a substantially uniform recess entrance width (opening width) and protrusions formed around the recesses, consommé powder with oil and moisture attached. It was found that when large agglomerates (powder) such as curry powder coexist with fine powder (aggregate), the adhesion suppressing effect cannot be improved as much as expected.

If such powder adhesion problem can be improved, various problems mentioned above (causing poor discharge, clogging, decrease in production efficiency, increase in defective products, etc.) can be solved, and oil and moisture adhesion can be solved. It can also greatly contribute to the reduction of food loss (food waste) in the processing process of the above-mentioned powder and cooking powder used for snacks.

The present invention has been made in view of the above-mentioned actual situation, and even for powders, especially powders with oil and water content such as those with a particle size of 1 μm or less, the surface that comes into contact with the powder can be treated. An object of the present invention is to provide a powder adhesion suppressing member having composite dimples capable of suppressing adhesion of powder and a surface treatment method thereof.

For this reason, the powder adhesion suppression member according to the present invention is
On at least the surface of the area that comes into contact with the powder, large unevenness is formed by forming relatively large-sized dimple-shaped concave portions and unevenly counted ridge-shaped convex portions around the concave portions. A powder adhesion suppressing member formed with fine unevenness in which dimple-shaped recesses smaller than the dimple-shaped recesses and a number of ridge-shaped protrusions are unevenly formed around the dimple-shaped recesses,
The powder is a powder to which at least one of water and oil is attached,
The range of the minimum value and maximum value of the recess entrance width of the large unevenness is 35 μm to 120 μm, and the range of the minimum value and maximum value of the depth is 5 μm to 20 μm,
The range of the minimum value and the maximum value of the recess entrance width of the fine unevenness is 1.8 μm to 15 μm, and the range of the minimum value and the maximum value of the depth is 1 μm to 5 μm.
It is characterized by

In the present invention, the powder can be characterized in that it includes particles having a particle size of 1 μm or less and particles having an aggregated particle size of 200 μm or more.

The present invention can be characterized in that the powder is food powder.

The present invention can be characterized in that the substrate is made of stainless steel or a resin material .

The powder adhesion suppression surface treatment method for a member according to the present invention comprises:
After forming, on at least the surface of the area that contacts the powder, large unevenness in which relatively large-sized dimple-shaped recesses and a number of ridge-shaped protrusions are unevenly formed around the recesses,
It is a surface treatment method for suppressing adhesion of powder to a member in which fine unevenness is formed by forming dimple-shaped recesses smaller than the large unevenness and a number of ridge-shaped protrusions unevenly on the periphery of the large unevenness. hand,
The powder is a powder to which at least one of moisture and oil is attached,
The range of the minimum value and maximum value of the recess entrance width of the large unevenness is 35 μm to 120 μm, and the range of the minimum value and maximum value of the depth is 5 μm to 20 μm,
The range of the minimum value and the maximum value of the recess entrance width of the fine unevenness is 1.8 μm to 15 μm, and the range of the minimum value and the maximum value of the depth is 1 μm to 5 μm.
It is characterized by

According to the present invention, a composite dimple capable of suppressing adhesion to a surface that comes into contact with powder, especially powder to which oil or water is attached, such as particles having a particle size of 1 μm or less, is provided. It is possible to provide a powder adhesion suppressing member and a surface treatment method thereof.

It is an enlarged image (100 times) of general consommé powder (aggregated particles, secondary particles). It is an enlarged image (15000 times) of the same consommé powder (primary particles). 1 is an enlarged surface image (SEM image, 400×) of a powder contact member (powder adhesion suppressing member) (sample (1)) having a composite dimple surface according to an embodiment of the present invention. FIG. 4 is an enlarged surface image (3D image, 400×) of the powder contact member (powder adhesion suppressing member) (sample (1)) having a composite dimple surface according to the embodiment; FIG. FIG. 4 is a diagram for schematically explaining the surface shape measurement result of the composite dimpled surface (sample (1)) according to the embodiment of the invention and its characteristics. It is a figure which shows an example of the surface shape data of the sample (1) based on embodiment same as the above. It is a figure which shows an example of the surface shape data of the sample (2) based on embodiment same as the above. A smooth surface of a stainless steel plate (blank just polished with #700), a conventional small-sized dimple uneven surface (sample with small dimples only), a conventional large-size dimple uneven surface (sample with large dimples only), It is a contact angle measurement result when olive oil is dropped on a sample of a composite dimple surface according to the form. (A) is an image obtained by observing the state of the surface when olive oil is dropped on the surface of a stainless steel plate on which only conventional large-sized dimple uneven surfaces (large dimples) are randomly formed, and (B) is an image of the stainless steel plate. FIG. 2C is an image obtained by observing the state of a surface when olive oil is dropped on a surface on which only conventional small-sized dimple uneven surfaces (small dimples) are randomly formed, and FIG. It is the image which observed the state of the surface when olive oil was dripped on the surface (large and small dimple surface). Movement of oil on the surface of a stainless steel plate "when a conventional single-sized dimple uneven surface (single dimple surface) is randomly formed" and "when oil adheres to the composite dimple surface according to the present embodiment" It is a schematic diagram (explanatory drawing of an adhesion suppression mechanism) shown for comparison. (A) is a surface enlarged image showing the results of a powder adhesion test using consommé powder on a smooth surface (mirror surface) of a stainless steel plate, and (B) shows the results of a powder adhesion test on a composite dimple surface according to the present embodiment. It is a surface enlarged image shown. It is a list of the results of comparing the powder adhesion using various surface shape samples. It is a cross-sectional SEM image of a single minute concave portion experimentally formed by one-shotting a medium used for fine particle peening processing, which is an example of shot material projection processing. It is a recessed part cross-sectional SEM image by laser processing.

An embodiment according to the present invention will be described below with reference to the accompanying drawings. It should be noted that the present invention is not limited by the embodiments described below.

As described above, the present invention and the like employ dimple-shaped concave portions having substantially uniform opening (entrance) sizes (width (length), diameter, etc.) and convex portions formed around the dimple-shaped concave portions. On the uneven surface, aggregates of large-sized (lump-like) powders (powder) aggregated like consommé powder and curry powder containing oil and water (attached with oil and water), and fine powders ( It was confirmed that the effect of suppressing adhesion is small when individual powders (primary particles) are mixed. Therefore, it has been necessary to find a surface shape having another form of fine unevenness that can be expected to suppress the adhesion of powder containing oil or water (to which oil or water is adhered).

For this reason, the inventors of the present invention repeated various experiments and researches, and found that different particle size media were separately placed on the surface of the powder contact member (for each different particle size media). By projecting the particle size media and then the small particle size media, unevenness (large unevenness ) While maintaining the shape, in the next projection, a fine unevenness (small unevenness) shape consisting of dimple-shaped recesses (small dimples) that are smaller than the large unevenness and ridge-shaped protrusions around it. By forming a surface (composite dimple surface) having a random uneven shape (composite dimple) that combines large and small dimples, the powder contact member having this composite dimple surface is protected from oil and moisture. Agglomeration of large size (lump) powder (powder) such as consommé powder and curry powder mixed with fine powder (individual powder). The present inventors have obtained new knowledge that adhesion of powder to such powder can be effectively suppressed.

Here, individual powders (individual particles, powder) are primary particles, and aggregates (secondary particles) are aggregates in which a plurality of individual particles (individual particles, powder) are aggregated with moisture or oil intervening. A powder in which these are mixed is sometimes called an aggregate. In addition, in the case of powder (powder), there are fine (fine) powder (individual particles, powder) with a particle size of 1 μm or less, aggregates of large size, and aggregates in which these are mixed. It may mean something.
Further, the term "average particle size" used herein means the median size, and this applies to both the particle size of the powder and the particle size of the projection material (media).

Also, regarding the size of the recess to be formed, there are various shapes such as when the entrance is approximately circular when viewed from the direction orthogonal to the surface, and when it is polygonal. diameter, etc.) can be used, and the expression can be used as the entrance width (opening width) of the recess when the surface shape is measured by a shape measuring device (for example, a laser type shape measuring device).

By the way, the inventors of the present invention also created a new manufacturing method for forming a surface (composite dimple surface) having a random uneven shape (composite dimples) formed by combining large and small dimples as described above for the purpose of this experiment. It is.
The feature of this manufacturing method is that in the first large-particle-particle projection, the projection energy is large, and an uneven surface is formed by hardening the surface layer of the powder-contacting member (for example, stainless steel). Since the energy is small, it is possible to combine the minute irregularities while maintaining the originally formed irregularities. It should be noted that, when a medium having a mixture of large grains and small grains was used for projection at one time, it was not possible to obtain a surface shape in which large unevenness and small unevenness are combined as in the present invention.

A powder contacting member (corresponding to a powder adhesion suppressing member according to the present invention) having a composite random uneven shape (composite dimples) formed by the method of the present invention on its surface is coated with oil or water ( including oil and water) powder (aggregates in which large aggregates of powder aggregated to a size of about 200 μm or more, for example, and individual fine powders having a particle size of about 1 μm or less are mixed) , Agglomerates with oil or moisture attached or individual fine powders exist independently, aggregates with large particle size distribution without oil or moisture attached, aggregates in which various types of powder are mixed It has been confirmed that the adhesion suppressing effect is exhibited even for powder, for example, individual powder having a particle size of about 1 μm or less, for example, individual powder having a particle size of about 200 μm or more.

Here, the present inventors initially believed that the surface (composite dimple surface) of the powder contact member formed with the composite dimples according to the present invention exhibits oil repellency that repels oil, so that fine powder ( Although it was thought that the adhesiveness of the powder) could be improved, in fact, unexpectedly, it showed lipophilicity (oil wettability) compared to the untreated stainless steel surface. However, the surface (composite dimple surface) of the powder contact member on which composite dimples are formed according to the present invention contains fine powder (powder particles) with a particle size of 1 μm or less, agglomerated large-sized aggregates, and these. It was confirmed that there is a clear powder adhesion effect for powders (aggregates) as well. The mechanism will be described later.

In addition, the entrance portion size (recess entrance width, opening width ) can be substituted by the unevenness pitch (interval between adjacent concave portions or interval between adjacent convex portions) measured from the surface shape. In the shot material projection process, dimple-like minute recesses and ridge-like protrusions around the recesses are unevenly formed on the surface (a plurality of (countless) crater-like minute recesses are randomly formed on the surface). can be expressed as

In the present embodiment, sample (1) is a base material obtained by polishing the surface of a stainless steel plate material made of SUS304 with a P700 buff, and on the surface thereof, a complex dimple-shaped microrecess of various sizes is formed. Surface treatment to form (composite dimple formation treatment by shot material projection treatment) is performed. Media (shot material) with a particle number of 60 (median particle diameter of 212 to 250 μm) is subjected to a blasting process (blasting process) by blasting it with compressed air of about 1/number (for example, 0.3) MPa. Abrasive material manufactured by Fuji Seisakusho, Fujirandom C particle number 3000 (central particle size 4.0 ± 0.5 μm) media (projection material) 1 / several (for example, 0.4) MPa Projection with compressed air Projection processing (projection processing) was applied.

Sample (2) was produced using the used media used in the previous shot material projection treatment (formation of large dimples) in sample (1). For forming the small dimples of sample (2), the same new medium as the medium used for the shot material projection treatment (formation of small dimples) subsequent to sample (1) was used.

FIG. 3 and FIG. 4 show enlarged images of the surface of sample (1) subjected to shot material projection treatment. FIG. 5 shows an image diagram schematically showing fine unevenness (a concave portion and a ridge-like convex portion around the concave portion) formed by the shot material projection process. As a feature of this method, large dimples are formed using a large grain blasting material in the first stage, and small dimples are formed using a small grain blasting material in the second stage. Dimples can be formed. Such distinct composite dimples are not formed, for example, when blasting materials having different particle diameters are mixed and blasted.

Surface enlarged images and measurement data (surface shape data) in the present embodiment, including those described later, are from actual surface texture measurement data, and are measured by a shape measuring device (a shape measuring laser microscope manufactured by KEYENCE) VK-X100).

Surface shape data of samples (1) and (2) are shown in FIGS. 6 and 7, respectively.
In the sample (1), as shown in FIG. 6, the large dimples (recesses of large unevenness, the same applies hereinafter) have a range of the minimum value and the maximum value of the unevenness pitch of about 50 to 120 μm (in other words, the range of the unevenness pitch is The minimum value is 50 μm or more and the maximum value is about 120 μm or less. is 10 μm or more, and the maximum value is about 20 μm or less.The same shall apply hereinafter.) Small dimples (recesses of fine unevenness, the same shall apply hereinafter) have a range of the minimum and maximum values of the unevenness pitch of about 1.8 to 8 μm. , the range of the minimum and maximum values of the recess depth is in the range of about 2 to 5 μm, and the ratio of the large dimples to the small dimples is in the range of about 6 to 60. , the ratio of the recess depth is in the range of about 2 to 10.
In the following, when the ranges of the uneven pitch (entrance width of the recess, the opening width of the opening, the opening diameter) and the size of the depth of the recess are shown, the minimum value of the pitch of the recess and the depth of the recess and The range of maximum values shall be indicated.

On the other hand, in the sample (2) using the used media for forming the large dimples, as shown in FIG. 7, the large dimples had a pitch of protrusions and recesses of about 35 to 100 μm and a depth of recesses of about 5 to 7 μm. , the small dimples have a pitch of recesses and protrusions in the range of about 2 to 15 μm, and a depth of recesses in the range of about 1 to 3.2 μm. The range is about 2 to 50, and the recess depth ratio is about 1.5 to 7. It is considered that the size and depth of the large dimples were reduced because the grain size of the media used was reduced due to wear and chipping.

Powders containing particles with a particle size of 1 μm or less (targets for adhesion suppression) include edible powders such as consommé powder, wheat flour, cornstarch, potato starch, green tea powder, cocoa powder, powdered sugar, and curry powder, and pharmaceutical powders. There are powders such as (powder medicine), and it is assumed that there are powders with a particle size of 1 μm or less and those with a particle size of 200 μm or more, and various shapes are included. Such particles with a small particle size of 1 μm or less are attracted to surrounding powders to form relatively large lumps (powder aggregates), and the lumps are scattered over the entire surface of the powder contact surface. It is conceivable that a phenomenon such as the presence of Even in a mixed powder (aggregate) that is a mixture of such fine particles (primary particles) and aggregates (secondary particles) in which a plurality of primary particles are aggregated, oil and moisture adhere to the particles. In consommé powder and curry powder, it was difficult to suppress the adhesion of powders of all particle sizes to a randomly uneven surface having relatively uniform recess inlet sizes (opening width, diameter, etc.).

Accordingly, the present inventors have found a method of forming an uneven surface having composite dimple recesses (composite dimple surface), and a powder contact member (for example, a stainless steel plate) having such a shape formed on the surface is coated with food. It was found that there is an effect of suppressing adhesion to the above-mentioned mixed powder (mixed powder such as consommé powder and curry powder with oil and moisture adhering), which is often used for powders for food.

The present inventors initially thought that a surface with low oil wettability (high oil repellency) would be effective in suppressing the adhesion of powder (powder) to which oil or the like adheres. However, as shown in the contact nucleus measurement results with olive oil in FIG. 8, the uneven surface having composite dimples (composite dimple surface) according to the present invention has high oil wettability (low oil repellency) at a visual level. ) resulted.
Therefore, when the presence of oil was observed at a high magnification, it was found to be an interesting situation in which oil gathered in large concave portions (large dimples) and hardly existed in small concave portions (small dimples), as shown in FIG. have understood.

9 will be described in more detail, each surface treatment surface (surface with only large dimples (FIG. 9(A), surface with only small dimples (FIG. 9(B)), compound dimple surface (FIG. 9(C))) 0.5 mL of olive oil was dropped on a SUS304 #700 plate material (powder contact member) having a , and allowed to stand still for 1 minute.
It was confirmed that olive oil spreads over the surface of only large dimples (Fig. 9(A)) or the surface of only small dimples (Fig. 9(B)) and the base material surface is not exposed.

On the other hand, on the composite dimpled surface, convex portions on the surface are exposed.
This is considered to be due to the following mechanism (theory).
In other words, the presence of dimples of different sizes on the surface of the base material causes a difference in surface free energy, and oil is attracted to large dimples with smaller surface free energy. pulls away, and the surface of the base material is exposed (see FIG. 10).
Due to such unique characteristics, the compound dimple surface (Fig. 9(C)) is exposed to powder on the convex surface of the small dimples, so that the surface with only large dimples or only small dimples is exposed. Compared to the surface, it is considered that the effect of improving slipperiness and suppressing adhesion can be exhibited. This mechanism (theory) is consistent with the fact that the large and small dimple surfaces were oleophilic surfaces as a result of the oil repellency angle.

As a result of actually examining the adhesion of the powder using consommé powder (consommé soup powder) as the powder, as shown in FIG. ), it was found to be superior to the untreated stainless steel plate of ) in suppressing adhesion of powder.
For the details of the adhesion test method, after washing with a neutral detergent, the surface of each test piece was cleaned with ethanol, tilted at 45 degrees, and about 1 tablespoon of consommé powder (particle size several μm to several hundred μm) was placed on it. was sprinkled 15 times each. After that, the surface of the test piece was observed with a digital microscope (KEYENCE VHX-7000).
In FIG. 11, the portion that looks white in the image is consommé powder remaining on the surface of the test piece. While many dimples remain on the mirror surface (FIG. 11(A)), it can be confirmed that almost no dimples remain on the composite dimple surface (FIG. 11(B)).

Furthermore, several kinds of edible powders were used, and stainless steel surfaces subjected to various treatments were used to relatively evaluate the adhesion of the powders (powder). Those representative results are collectively shown in FIG.
Determination of adhesiveness, such as the untreated product in FIG. The level at which a part of the remains partially is "Slightly attached △", and the level of the result (no adhesion) of the surface having the composite uneven shape (composite dimple) according to the present invention shown in Fig. 11 (B) is " Good 0”.

From the results of FIG. 12, the members (Examples 1 to 5) having a composite concave-convex shape (composite dimples) according to the present embodiment have an untreated stainless steel plate and a relatively uniform concave entrance size (opening width of the opening). It was found that, compared to samples with random uneven shapes, the sample had a remarkable effect in suppressing the adhesion of the mixed powder, which is often used in food powders.

Regarding the size of the composite dimples formed by the fine unevenness forming process (shot material projection process) according to the present embodiment, from FIGS. The interval between recesses or the interval between adjacent protrusions) is 150 μm or less (considering manufacturing variations, measurement variations, etc.), preferably about 30 to 150 μm, and the depth of the recesses is about 5 to 30 μm (manufacturing variations , considering measurement variations), and is preferably about 5 to 20 μm.
In addition, the unevenness pitch of the small dimples (microscopic unevenness) is 20 μm or less, about 1.0 to 20 μm (considering manufacturing variations, measurement variations, etc.), preferably about 1.8 to 15 μm, and the depth of the recess is 1. 0 to 5.0 μm.
Further, the ratio of the uneven pitches of the large and small dimples is about 2 to 60:1, and the ratio of the depths of the large and small dimples is about 2 to 20:1 (considering manufacturing variations, measurement variations, etc.), preferably. It is about 1.5 to 10:1.

As described above, according to the powder adhesion suppressing member having the composite dimple surface according to the present embodiment, powder, especially powder having a particle size of 1 μm or less to which oil or moisture adheres (agglomeration) It is possible to provide a powder adhesion suppressing member having a composite dimple surface capable of suppressing adhesion of powder to a surface in contact with the powder, and a surface treatment method thereof.

By the way, in the fine unevenness forming process (shot material projection process) according to the present embodiment, the projection material (media, shot material) as described above is ejected from a known injection device to form a member such as a contact member to be processed. It can be done by colliding with a surface.

For example, a blasting device can be used as the injection device, and as an example of the blasting device, for example, "PNEUMA BLASTER" (type: SC series, SG series, etc.) manufactured by Fuji Seisakusho Co., Ltd. can be used. can. Further, for example, those described in JP-A-2019-25584 can be used.

More specifically, as an injection device that injects injection granules toward the surface of a member, a known blasting process that injects a blast material (media, shot material) together with a compressed gas (air, argon, nitrogen, etc.) A device (blasting device) can be used.

The blasting equipment (blasting equipment) is a suction type blasting equipment that injects the blasting material using the negative pressure generated by the injection of compressed gas, and the blasting material dropped from the blasting material tank into compressed gas. Gravity type blasting equipment that carries and injects blasting material. Compressed gas is introduced into the tank containing the blasting material, and the blasting material flow from the blasting material tank is merged with the compressed gas flow from the separately given compressed gas supply source. A direct-pressure blasting device that jets the compressed air, and a blower-type blasting device that jets the above-mentioned direct-pressure compressed gas flow on a gas flow generated by a blower unit are commercially available. Both can be used for jetting the above-described projection material.
A water jet can also be used, which shoots a shot at high pressure along with a liquid such as water.

By the way, in the present embodiment, it has been described that the dimple-shaped minute recesses formed in multiple stages are all randomly formed by the shot material projection process. Chemical polishing (chemical etching) or plasma treatment (for example, argon bombardment treatment) is applied to the surface of the surface to form large unevenness, and then a plurality (a large number) of fine unevenness is randomly formed on the surface by shot material projection treatment. can. However, the present invention is not limited to these, and the large dimples and small dimples according to the present invention are formed by at least one of chemical etching, plasma treatment, shot material projection treatment, etc., or an appropriate combination thereof. is also possible.
As chemical polishing (chemical etching), for example, it is assumed that acidic chemicals such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, iron chloride (III), etc. are prepared in an aqueous solution at an arbitrary ratio and used.

In addition, in order to form a composite concave-convex shape (composite dimple) on the surface of a member such as a contact member to be processed, a composite concave-convex shape (composite dimple) formed by chemical etching, plasma treatment, shot material projection treatment, etc. is applied to the surface. It also includes the case of forming a composite concave-convex shape (composite dimple) on the surface of a member such as a contact member to be processed by, for example, transfer using a mold possessed by the method.

The powder adhesion suppressing member according to the present invention can be applied, for example, to powder contact members in general with which powder comes into contact. It is applicable to a variety of powder-contacting members, including powder-placement parts, slide-down devices (eg, shooters, etc.), sieves, agitating devices, cooking balls, cooking utensils, and the like.

In addition, in the present embodiment, for example, in the case of stainless steel, non-magnetic austenitic stainless steel (SUS303, 304, 316, etc.). In addition, the present invention can be applied to metal materials other than stainless steel (for example, in the case of iron, steel (SS400, etc.), metals such as aluminum and titanium, or alloys).

The powder adhesion suppressing member according to the present invention can also be a resin member, and the material thereof is not particularly limited. For example, it is also possible to use ceramics.

Here, in the present invention, in order to specify the uneven surface formed by the shot material projection treatment from the shape or structure, a geometrical and regular uneven shape formed according to a drawing designed in advance by laser processing or the like is used. In contrast, a specific method is used in which dimple-shaped minute concave portions and ridge-like convex portions around the concave portions are formed unevenly in shape, pitch, and depth.
In other words, instead of using the expression ``fine unevenness is formed on the surface by shot material projection treatment,'' the expression ``on the surface, relatively large dimple-shaped concave portions and ridge-like convex portions around them are unevenly formed. ``On top of the large unevenness, dimple-shaped recesses that are smaller than those and ridge-shaped protrusions are formed unevenly and innumerably to form microscopic unevenness.'' The identification method (expression) of is used.
However, in comparison with the prior art, etc., it may be difficult to adopt the above identification method (expression) as a characteristic identification method (expression) that distinguishes the uneven surface formed by the shot material projection treatment from others. is also assumed.

For this reason, it is assumed that the uneven surface formed by the shot material projection process must be specified by the specifying method (expression) of "forming minute unevenness on the surface by the shot material projection process."
Therefore, at the time of the filing of the present application, it was impossible or unrealistic to specify the fine unevenness formed by the shot material projection treatment by the shape, structure, characteristics, etc. It is necessary to use the expression "by forming fine unevenness on the surface" in some cases, which will be explained below.

In the shot material blasting process, blasted particles (media) are collided with the surface to be processed through compressed air at a speed of several tens to 100 m/s or more, and have convex portions on the edges without significant dimensional change. Approximately spherical, micron-sized minute recesses are irregularly formed on substantially the entire surface of the processing surface. The periphery is raised to form a convex portion (see FIG. 13), and the raised convex portion is dented by collision with other media, so that the height of the convex portion becomes irregular.

On the other hand, mechanical processing such as laser processing and cutting forms regular recesses, and since it is removal processing, no protrusions are formed (the protrusions do not rise with the formation of the recesses). ). Therefore, in mechanical processing such as laser processing and cutting, the height of the protrusions around the minute recesses does not match the height of the surface (original surface of the material) of the material to be processed (the member being laser processed). (See FIG. 14).

In addition, since the fine irregularities formed by the shot material projection process are formed irregularly (randomly) innumerably, the surface texture (shape) formed by the shot material projection process is not the same as the surface texture (shape) formed by the polishing or grinding process. It is different from the surface shape (texture) formed by scraping and giving scratches (grooves such as streaks), but when measured with a surface roughness meter etc., both are numerically similar values. Therefore, it is impossible to distinguish between the two by surface roughness or the like.

However, the effect obtained by the surface texture (shape) formed by the shot material projection process (powder adhesion suppression effect) is the surface shape ( It is a special thing that cannot be predicted from the texture).
In addition, from the shot peening treatment, in which the fatigue limit is improved by colliding media of the order of several millimeters to impart residual stress, it is impossible to predict that the surface subjected to the shot material blasting treatment will have the effect of suppressing powder adhesion. It is.

In this way, the fine irregularities formed by the shot material projection process are formed irregularly (randomly) innumerably, and the shapes of the fine recesses and the protrusions around them are irregular, and the irregularities are the characteristics of the present invention. Therefore, the expression "formed by the shot material projection process" is used as a term for specifying the surface texture (shape) formed by the shot material projection process. The surface formed by the shot material projection process cannot be specified except by using .
As described above, it is impossible and unrealistic at the time of the filing of the present application to specify the fine unevenness formed by the shot material projection process by the shape, structure, characteristics, and the like.

By the way, in the present embodiment, the case where the shot material projection process, which is the process of forming unevenness on the surface of at least the area in contact with the powder, is performed in two steps (two steps) has been exemplified. However, it also includes the case where the shot material projection process is performed by changing the particle size in multiple stages of two or more times.

By the way, the present invention is not limited to the embodiments of the invention described above, and various modifications can be made without departing from the gist of the invention.

Claims (5)

On at least the surface of the area that comes into contact with the powder, large unevenness is formed by forming relatively large-sized dimple-shaped concave portions and unevenly counted ridge-shaped convex portions around the concave portions. A powder adhesion suppressing member formed with fine unevenness in which dimple-shaped recesses smaller than the dimple-shaped recesses and a number of ridge-shaped protrusions are unevenly formed around the dimple-shaped recesses,
The powder is a powder to which at least one of water and oil is attached,
The range of the minimum value and maximum value of the entrance width of the concave portion of the large unevenness is 35 μm to 120 μm, and the range of the minimum value and maximum value of the depth is 5 μm to 20 μm,
The range of the minimum value and the maximum value of the entrance width of the concave portion of the fine unevenness is 1.8 μm to 15 μm, and the range of the minimum value and the maximum value of the depth is 1 μm to 5 μm.
A powder adhesion suppressing member characterized by: 2. The powder adhesion suppressing member according to claim 1, wherein the powder includes particles having a particle size of 1 [mu]m or less and particles having an aggregated particle size of 200 [mu]m or more. 3. The powder adhesion suppressing member according to claim 1, wherein the powder is food powder . 4. The powder adhesion suppressing member according to any one of claims 1 to 3 , wherein the base material is made of stainless steel or a resin material . After forming, on at least the surface of the area that contacts the powder, large unevenness in which relatively large-sized dimple-shaped recesses and a number of ridge-shaped protrusions are unevenly formed around the recesses,
It is a surface treatment method for suppressing adhesion of powder to a member in which fine unevenness is formed by forming dimple-shaped recesses smaller than the large unevenness and a number of ridge-shaped protrusions unevenly on the periphery of the large unevenness. hand,
The powder is a powder to which at least one of water and oil is attached,
The range of the minimum value and maximum value of the entrance width of the concave portion of the large unevenness is 35 μm to 120 μm, and the range of the minimum value and maximum value of the depth is 5 μm to 20 μm,
The range of the minimum value and the maximum value of the entrance width of the concave portion of the fine unevenness is 1.8 μm to 15 μm, and the range of the minimum value and the maximum value of the depth is 1 μm to 5 μm.
A surface treatment method for suppressing adhesion of powder to a member, characterized by:

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