JP5295611B2 - Wiper arm with excellent lightness and appearance - Google Patents

Description

  The present invention relates to a wiper arm that is excellent in lightness and appearance.

  A wiper that secures visibility by wiping the glass surface in the rain is mainly composed of a wiper blade and a wiper arm. The wiper blade is a part that wipes the glass surface. The wiper arm is a component that connects a wiper blade and a main body (such as a vehicle) including the wiper.

  The wiper arm is usually formed by processing a steel plate and has a substantially U-shaped cross section (Patent Document 1). In response to the trend of lighter automobiles in recent years, the wiper is also required to be lighter, and the wiper arm, which is its main component, is also required to be lighter.

On the other hand, since the wiper arm is attached to the outside of an automobile and easily visible, it is required to have excellent appearance. In particular, when the wiper arm is corroded, red rust is generated and the appearance may be significantly impaired. Usually, a wiper arm is coated and manufactured after a steel sheet is subjected to bending or the like (Non-Patent Document 1). At this time, the end portion of the wiper arm is also painted, but the end surface portion is likely to be corroded because it may be difficult to paint. The end surface portion of the steel plate is usually the end portion of the horizontal leg portion of the wiper arm, and this end portion is present at a position that can be seen by the driver when installed in the automobile. Therefore, when red rust or the like due to corrosion is generated in this portion, the appearance of the wiper may be remarkably impaired.
JP 2003-146189 A “Powder Coating '98”, No.2, p.33

  As described above, the wiper arm is required to have light weight and appearance, but there has not yet been a satisfactory one. In view of these circumstances, an object of the present invention is to provide a wiper arm having excellent lightness and appearance.

As a result of intensive studies, the inventors have found that the above object can be achieved by a specific shape of the wiper arm, and have completed the present invention.
That is, the said subject is solved by the following this invention.

[1] A wiper arm having a substantially U-shaped cross section having a ceiling portion and a pair of horizontal leg portions,
An end of the horizontal leg is a wiper arm that is bent inward to form an edge.
[2] The wiper arm according to [1], wherein the edge portion is formed by bending the end of the horizontal leg portion 90 degrees or more inside the wiper arm.
[3] The wiper arm is obtained by processing a steel plate.
The wiper arm according to [1] or [2], wherein the steel plate is a primer steel plate having a primer coating formed on the surface of the steel plate before the processing.
[4] The wiper arm according to [3], wherein the wiper arm has the primer coating film on an inner surface thereof.
[5] The wiper arm according to [3] or [4], wherein the wiper arm further includes a post coat coating formed after the processing on the primer coating.
[6] The wiper arm is obtained by processing a steel plate.
The steel sheet is a pre-coated steel sheet having a primer coating film formed on the steel sheet surface before the processing and a second coating film formed on the primer coating surface before the processing. Wiper arm.
[7] A wiper including the wiper arm according to any one of [1] to [6].
[8] A step of preparing a primer steel plate having a primer coating on the surface of the steel plate,
A step of bending the primer steel plate,
The method for manufacturing a wiper arm according to [1] to [5].
[9] A step of preparing a pre-coated steel sheet having a primer coating film formed on the surface of the steel sheet and a second coating film formed on the primer coating film,
A step of bending the pre-coated steel sheet,
The method for manufacturing a wiper arm according to [1] or [6].

  According to the present invention, a wiper arm excellent in light weight and corrosion resistance can be provided.

1. The wiper arm of the present invention has a substantially U-shaped cross section having a ceiling portion and a pair of horizontal leg portions, and the end of the horizontal leg portion is bent inward to form an edge portion. Features.
FIG. 1 is a perspective view showing an example of a wiper arm of the present invention. In FIG. 1, 1 is a wiper arm, 1a is a wiper blade connecting portion, 1b is a rotating bearing portion, 10 is a ceiling portion, 20 is a lateral leg portion, and 30 is an edge portion. The rotation shaft is a shaft for driving a wiper provided in a vehicle or the like.

  The ceiling portion is a portion corresponding to a bottom surface having a U-shaped cross section, and is a portion represented by 10 in FIG. The cross-sectional U-shape means that the cross-sectional shape is a U-shape or a shape similar thereto. In FIG. 2, which is a cross-sectional view taken along line ZZ in FIG. 1, the ceiling portion 10 is a straight line, but may be a curved line. The width | variety of the ceiling part 10 is not specifically limited, What is necessary is just the width | variety of a normal wiper arm. Further, the width of the ceiling portion 10 does not have to be constant in the longitudinal direction of the wiper arm 1.

The pair of horizontal leg portions are portions provided so as to extend substantially vertically from both ends (also referred to as “both edges”) of the ceiling portion 10 in the longitudinal direction, and are portions represented by 20 in FIG. Substantially vertical means that it does not have to be strictly vertical. More specifically, “substantially vertical” means that in FIG. 2, the angle α formed by the ceiling portion 10 and the lateral leg portion 20 is about 70 to 110 degrees. The side legs 20 are preferably formed by bending a steel plate, and the angle at which the steel plate is bent in such bending is referred to as a “bending angle”. Α is also referred to as a bending angle of the lateral leg. It is preferable that an arc having a certain radius of curvature is formed in the processed portion. The radius of curvature of the arc 25 formed inside the wiper arm is preferably 0 to 5.0 mmR.
In FIG. 2, the horizontal leg 20 is a straight line, but may be a curved line. The height of the horizontal leg portion 20 is not particularly limited as long as it is a normal wiper arm height. Further, the height of the lateral leg portion 20 does not need to be constant in the longitudinal direction of the wiper arm. In the present invention, the symbol “˜” includes numerical values at both ends thereof.

  The ends of the side legs 20 are folded inward to form the edges 30 as shown in FIG. Since the wiper arm 1 of the present invention has this edge portion 30, it has excellent strength, and the thickness of the wiper arm (t in FIG. 2) can be made thinner than that of a conventional wiper arm. For this reason, the wiper arm of the present invention is excellent in lightness.

  It is preferable that the edge part 30 is provided over the longitudinal direction of the horizontal leg part 20. The width 31 of the edge 30 is preferably 2 to 10 mm, and more preferably 3 to 5 mm. If the width is less than 2 mm, the workability of the bending process may be lowered. Conversely, if the width exceeds 10 mm, the weight of the wiper arm increases and it may be difficult to reduce the weight. The width 31 of the edge 30 is preferably constant over the longitudinal direction of the horizontal leg 20.

The edge portion 30 is preferably formed by bending the end of the horizontal leg portion 20 90 degrees or more inside the wiper arm 1. The bending angle of the edge 30 is represented by β in FIG. The wiper arm whose edge 30 has a bending angle of 90 degrees or more is excellent in strength, and the wiper arm whose bending angle exceeds 90 degrees is particularly excellent in strength.
When the wiper arm whose edge 30 has a bending angle of 90 degrees or more is attached to an automobile, the end face of the edge 30 becomes difficult for the driver to see. Therefore, even if this part corrodes and red rust is generated, there is an advantage that deterioration of the appearance can be suppressed. Although it will not specifically limit if the bending angle of the edge part 30 is 90 degree | times or more, 90-180 degree | times is preferable.

  An arc having a certain radius of curvature may be formed in the bent portion. It is preferable that the arc 35 formed inside the wiper arm 1 has a radius of curvature of 0 to 5.0 mmR.

The wiper arm of the present invention is preferably made of a coated steel plate. A wiper arm made of a coated steel sheet can be roughly divided into the following three types according to the manufacturing method.
The first is a wiper arm (also referred to as “pre-prime type”) obtained by processing a “primer steel plate” having a primer coating film formed on a flat steel plate. A primer coating film refers to a coating film provided directly on the surface of a steel sheet.
The second is a wiper arm ("Precoat type") which is made by processing a "precoated steel sheet" having a primer coating film formed on a flat steel sheet and a second coating film formed on the primer coating film. It is also referred to as “
The third is a wiper arm (also referred to as a “pre-processed type”) formed by processing a steel sheet having no coating film into a wiper arm and then painting.
Each component will be described below. The number is omitted unless necessary.

2. Painted steel sheet A coated steel sheet is a steel sheet having a coating film on the surface of the steel sheet. A coating film is a film | membrane obtained by coating a coating material on the steel plate surface. The coated steel sheet used in the present invention has a coating film on the surface of the steel sheet. The steel plate in a coated steel plate is also called a base material or a coating original plate.

(1) Steel plate As the steel plate, a cold rolled steel plate, a plated steel plate or a stainless steel plate may be used. Examples of the plated steel sheet include a hot-dip Zn-plated steel sheet, a hot-dip Zn-Al alloy-plated steel sheet, a hot-dip Zn-Al-Mg alloy-plated steel sheet, and an iron ( An alloyed hot-dip Zn-plated steel sheet in which a Zn—Fe alloy is produced by diffusing Fe) is included. Since these steel plates have excellent corrosion resistance, they provide a wiper arm with excellent appearance. Especially, as a steel plate of this invention, a hot dip Zn plating steel plate, a hot dip Zn-Al alloy plating steel plate, or a hot dip Zn-Al-Mg alloy plating steel plate is preferable. This is because these steel plates are more excellent in corrosion resistance.

  The hot-dip Zn-plated steel sheet refers to a steel sheet plated using a Zn (zinc) hot-dip plating bath. The hot dip plating bath of Zn may contain a trace amount of metals other than Zn. Examples of metals other than Zn include Al, Pb, and Sb. These metals may be contained in the plating bath with Al: 0.10 or more and less than 0.20 mass%, Pb: 0.007 mass% or less, and Sb: 0.01 or more and less than 0.10 mass%. In addition, the Zn hot-dip plating bath may contain a small amount of inevitable impurities. Inevitable impurities are impurities that are inevitably mixed although not intended in the plating process.

  The hot-dip Zn-Al alloy-plated steel sheet refers to a steel sheet plated using a hot-dip plating bath of an alloy containing Zn (zinc) and Al (aluminum) as essential components. Preferable examples of such an alloy include an alloy whose Al is 3 to 10% by mass and the balance is substantially made of Zn, and an alloy whose Al is 50 to 60% by mass and the balance is substantially made of Zn. included. Among them, in the present invention, Al is 5% by mass and the balance is substantially “5% Al—Zn alloy”, or Al is 55% by mass, and the balance is substantially Zn. “55% Al—Zn alloy” is preferable. “The balance consists essentially of Zn” means that the balance contains Zn, does not impair the corrosion resistance of the plated steel sheet, and contains elements other than Zn and Al as long as the plated steel sheet itself can be produced. Including being out. Examples of elements other than Zn and Al include Si, Fe, and Mg. Preferable content of these elements is Si: 3.0% by mass or less, Fe: 1.5% by mass or less, and Mg: 0.5% by mass or less with respect to the alloy. In addition, the alloy may contain inevitable impurities such as Cu, Pb, Sn, Ca, Ni, Mn, Cr, Ti, Na, B, and Sr.

  The hot-dip Zn—Al—Mg alloy-plated steel sheet refers to a steel sheet plated using a hot-dip plating bath of an alloy containing Zn (zinc) as a main component and Al (aluminum) and Mg (magnesium) as essential components. . A preferable example of such an alloy includes a molten Zn—Al—Mg alloy in which Al is 3 to 22% by mass, Mg is 1 to 10% by mass, and the balance is substantially made of Zn. “The balance is substantially made of Zn” means that the balance contains Zn of 40% by mass or more, does not impair the corrosion resistance of the plated steel sheet, and is within the range where the production of the plated steel sheet is possible. Including elements other than Mg. Examples of elements other than Zn, Al, and Mg include Ti, B, Si, and Fe. Preferable content of these elements is Ti: 0.1% by mass or less, B: 0.05% by mass or less, Si: 2% by mass or less, and Fe: 2% by mass or less with respect to the alloy. In addition, the alloy may contain inevitable impurities.

  The alloyed hot-dip Zn-plated steel sheet is obtained by heating the Zn-plated steel sheet at about 450 to 650 ° C. to diffuse the iron (Fe) of the steel sheet as a base material into the plating layer to produce a Zn—Fe alloy. A steel sheet.

  Examples of the stainless steel sheet include austenitic, ferritic and martensite.

  The steel sheet used in the present invention is subjected to known coating pretreatment as necessary. Examples of the treatment include pickling and surface conditioning treatment (acid-based) on the surface of the steel sheet, followed by treatment for forming an arbitrary chromium-free pre-treatment coating film, and alkali degreasing treatment on the steel plate surface. Thereafter, an optional chromium-free coating pretreatment film is formed. These coating pretreatments improve the adhesion between the steel sheet and the coating film.

  The thickness of the steel plate in the present invention may be 1 to 2 mm which is the thickness of a steel plate usually used for a wiper arm. Since the wiper arm of the present invention has a bent edge as described above, it has superior strength compared to a wiper arm made of the same thickness steel plate. That is, the wiper arm according to the present invention can reduce the thickness of the steel plate compared to the conventional wiper arm when the same strength is to be obtained. Usually, the thickness of the steel plate used for the wiper arm is about 1.6 mm. When this is used as a reference, the thickness of the steel plate of the present invention is preferably 0.8 to 1.6 mm. It is more preferable to set it as 8-1.4 mm.

(2) Coating Film The coating film of the wiper arm of the present invention will be described by dividing it into various types of wiper arms.

1) Pre-prime type coating film This type of wiper arm consists of a primer coating film formed on a flat steel plate before being processed into a wiper arm, and a coating film formed by coating after processing if necessary. Have The coating applied after processing is also called “postcoat”, and the coating film formed by postcoating is also called “postcoat coating film”. The steel plate before being processed into the wiper arm refers to a steel plate that has not been punched or bent necessary for manufacturing the wiper arm. The coated steel sheet having the primer coating is also called “primer steel sheet”.

Since the primer coating film is formed on a flat steel plate, there is an advantage that the surface of the steel plate and the paint are firmly fitted in the coating process and are firmly adhered to the steel plate. Moreover, the coating film formed on the flat steel plate is excellent in film thickness uniformity in addition to good adhesion. For this reason, since the wiper arm containing such a primer coating film is excellent in corrosion resistance, it is also excellent in appearance.
It is preferable that the primer coating film is formed on both surfaces of the steel plate.

  The primer coating film may be obtained by painting a paint usually used for primer steel plates. Examples of paints usually used for primer steel plates include epoxy resins, epoxy / acrylic resins, phenoxy resins, polyester resins, acrylic / polyvinylidene fluoride resins, and the like. Of these, epoxy resins, epoxy / acrylic resins, phenoxy resins, and polyester resins are preferable. This is because these resins have a relatively high surface tension of 35 mN / m or more, so that in addition to the adhesiveness to the steel sheet, the resin has excellent adhesiveness to the postcoat coating film when the postcoat is applied.

  Moreover, when post-coating is performed, the primer coating may be subjected to etching treatment or the like. Examples of the etching process include a plasma process.

  The steel plate used for the primer steel plate is preferably subjected to chemical conversion treatment before the coating film is formed. This is because a uniform chemical conversion treatment layer is formed by chemical conversion treatment applied to a flat steel plate, and adhesion with the coating film can be further strengthened.

  The primer coating preferably contains a rust preventive pigment. That is, it is preferable that a rust preventive pigment is dispersed in a matrix resin made of a polymer compound. An antirust pigment is a pigment added in order to improve corrosion resistance. Examples of the anticorrosive pigment preferable in the present invention include calcium silicate, magnesium hydrogen phosphate, magnesium phosphate, and zinc phosphate. Among them, in the present invention, a rust preventive pigment containing Mg such as magnesium hydrogen phosphate or magnesium phosphate is more preferable. This is because the pigment dissolves in water from the coating film and flows out to reach the end face part to form a compound containing poorly soluble Mg on the end face part, and this hardly soluble compound suppresses corrosion.

Magnesium phosphate is a compound represented by Mg ₃ (PO ₄ ) ₂ . Magnesium hydrogen phosphate refers to magnesium magnesium phosphate represented by MgHPO ₄ or magnesium magnesium phosphate represented by Mg (H ₂ PO ₄ ) ₂ .

  The content of these anticorrosive pigments in the coating film is preferably 2 to 50 parts by mass with respect to 100 parts by mass of the matrix resin. When the addition amount of the rust preventive pigment exceeds the upper limit of the range, the processability of the coating film may be deteriorated, and when it is less than the lower limit of the range, the corrosion resistance effect may not be sufficient. Therefore, when the addition amount of the rust preventive pigment is within the above range, the balance between the workability of the coating film and the corrosion resistance is excellent.

  The thickness of the primer coating film is preferably 2 μm or more. However, if the coating film becomes too thick, it may cause an increase in cost, a decrease in workability, and the like. Therefore, the film thickness is preferably 2 to 10 μm. The film thickness here means an average film thickness. Although the average film thickness is measured by a known method, it is preferably measured by a gravimetric method. Because the film thickness is preferably uniform. The error range of the film thickness is preferably about ± 1 μm. In the pre-prime type wiper arm, since the primer steel plate is used, the thickness of the primer coating film is uniform with little error.

  Since the pre-prime type wiper arm is manufactured by cutting and bending the primer steel plate, the base is reliably exposed at the end surface of the steel plate. In general, a portion where the base is exposed is inferior in corrosion resistance, so that appearance is deteriorated. However, since the wiper arm of the present invention has an edge portion by bending the end portion of the horizontal leg portion, the appearance deterioration is small. Moreover, when a primer steel plate contains the said rust preventive pigment, the corrosion resistance of an end surface will improve more and an external appearance property will be improved more. Furthermore, post-coating is preferably applied to the end face, since the corrosion resistance of the end face is greatly improved and the appearance is further enhanced.

  The primer coating film of the present invention may contain additives such as a leveling agent, a defoaming material, a lubricant, and an ultraviolet absorber that are used in coated steel sheets for home appliances and building materials. This is because such a coated steel sheet is excellent in design and weather resistance. However, the primer steel sheet in which these additives are added to the coating film is likely to have poor adhesion to the post-coat coating film. Therefore, when applying a post-coat to a primer steel plate, it is preferable not to add the said additive to a primer coating film.

  As described above, in the present invention, it is preferable that a post coat coating film is formed on the primer coating film. In this case, the postcoat coating film may be formed on one side of the wiper arm, but may be formed on both sides. When the post coat film is formed on one side of the wiper arm, that side must be the front side of the wiper arm (the side opposite to the windshield when the wiper arm is attached to a car). preferable. This is because the appearance of the wiper arm can be improved.

  The post coat coating film may be formed by applying a paint generally used for coating a wiper. The coating may be performed according to a known method. Examples of the known coating methods include spray coating, powder coating, and brush coating, among which powder coating is preferable. The thickness of the top coat film is preferably 20 μm or more in consideration of appearance, corrosion resistance, and the like. Furthermore, when considering cost, weather resistance, corrosion resistance, etc., the film thickness is more preferably 30 to 200 μm.

2) Pre-coat type coating film This type of wiper arm is formed on a primer coating film formed on a flat steel plate before being processed into a wiper arm and on a primer coating film before being processed into a wiper arm. Having a second coated film. The second coating film is a coating film different from the primer coating film. In this type, the surface of the steel plate and the primer paint are well-matched in the painting process, and the primer coating is firmly attached to the steel plate. Similarly, since the 2nd coating film formed on a primer coating film also fits well with a primer coating film, the adhesiveness of a 2nd coating film and a primer coating film also becomes favorable. Furthermore, the uniformity of these film thicknesses is also excellent. For this reason, the precoat type wiper arm has excellent corrosion resistance and excellent appearance.

  The primer coating film in the precoat type may be the same as the coating film described in “Preprime type”. However, since the adhesion with the second coating film applied thereon is good, very good adhesion can be obtained without adjusting the surface tension or the like of the primer steel plate.

  What is necessary is just to form the 2nd coating film in a precoat type with the coating material generally used for a precoat steel plate. Examples of such paints include paints based on urethane resins, epoxy resins, polyester resins, acrylic resins / polyvinylidene fluoride resins, and the like.

  Since the precoat type wiper arm is manufactured by cutting and bending a precoated steel plate, the base is surely exposed at the end face of the steel plate. In general, a portion where the base is exposed is inferior in corrosion resistance, so that appearance is deteriorated. However, since the wiper arm of the present invention has an edge portion by bending the end portion of the horizontal leg portion, the appearance deterioration is small. Moreover, when a precoat steel plate contains the said rust preventive pigment, the corrosion resistance of an end surface will improve more and an external appearance property will be improved more.

3) Coating film in pre-processing type This type of wiper arm has a coating film formed after a steel sheet having no coating film is processed into a wiper arm shape. Since this coating film is a coating film formed after processing, it is the above-mentioned postcoat coating film. The coating film in this type may be only the primer coating film directly formed on the steel plate, and may further include a second coating film formed on the primer coating film. The primer coating and the second coating in this type may be provided in the same manner as the above two types of wiper arms.

  As described above, three types of wiper arms have been described, but the wiper arm of the present invention is preferably a preprime type or a precoat type, and more preferably a precoat type. In particular, since the wiper arm of the present invention has an edge and a complicated shape, it may be difficult to sufficiently coat the inside of the wiper arm. However, since the precoat type wiper arm is coated in advance, a coating film can be easily formed on the inside of the wiper arm.

  FIG. 3 is a sectional view showing an example of a wiper arm (preprime type) of the present invention made of a preprime steel plate. In FIG. 3, 2 is a steel plate, 3 is a chemical conversion treatment layer, 4 is a primer coating film, and 5 is a postcoat coating film.

3. Manufacturing method of wiper arm Although the wiper arm of the present invention is arbitrarily manufactured within a range not impairing the effects of the invention, a preferable manufacturing method will be described below.
(1) Preprime type wiper arm Preprime type wiper arm
(A) preparing a primer steel plate having a coating film provided on the surface of the steel plate;
(B) It is preferable to obtain the step of bending the primer steel plate.
The method for manufacturing a wiper arm of the present invention may further include a step of post-coating the primer steel plate obtained in the preceding step (C) after (B).

(A) Process This process is a process of preparing the primer steel plate in which the coating film was formed on the surface of the steel plate. Specifically, the primer steel plate is preferably prepared as described below. First, a steel plate as a coating original plate is prepared. These steel plates may be prepared as already described. The steel plate used here is a flat steel plate that has not been processed.

  Next, a paint is prepared. The paint is obtained by mixing a resin with a rust preventive pigment or the like. The means for mixing is not particularly limited, but it is preferable to use a stirrer, three rolls, a bead mill or the like. At this time, a solvent may be added. As described above, an epoxy resin or the like may be used as the resin used in this step.

  The primer steel plate may be obtained by applying the paint thus obtained on both surfaces of the steel plate (application process), and heating and drying the coating film (baking process). Examples of the method of applying the paint to the steel sheet include roll coating, curtain coating, die coating, and knife coating. Furthermore, you may paint by the continuous coating line using these. The coating amount of the paint is adjusted so as to obtain a desired film thickness. The baking process is preferably performed so that the ultimate plate temperature is 150 to 250 ° C.

(B) Process This process is a process of bending the primer steel plate obtained in the previous process into a wiper arm shape. By this step, a wiper arm having a substantially U-shaped cross section having a ceiling portion and a pair of horizontal leg portions, the end of the horizontal leg portion being bent inward to form an edge portion is formed. Is done. At this time, it is preferable that the edge portion is formed by bending the end of the horizontal leg portion 90 degrees or more inside the wiper arm. Further, as described above, an arc having a radius of curvature may be formed in the bent portion.
The bending process may be performed according to a known method. Moreover, you may perform the punching process which punches a primer steel plate in a desired shape before this process.

(C) Process This process is a process of post-coating the processed primer steel plate. The paint used in this step may be a paint generally used for wipers. The coating method may be a known method such as powder coating.

(2) Precoat type wiper arm Precoat type wiper arm
(D) preparing a pre-coated steel sheet having a primer coating film formed on the surface of the steel sheet and a second coating film formed on the primer coating film;
(E) It is preferable that the pre-coated steel sheet is manufactured by being bent.

(D) Process In this process, a primer coating film and a 2nd coating film are formed on the surface of a steel plate. The formation of the primer coating film may be performed as in the step (A). Moreover, you may form a 2nd coating film according to the said (A) process.

(E) Process This process is a process of bending the precoated steel plate obtained in the previous process into a wiper arm shape. This step may be performed in the same manner as the step (B).
Since the precoat type wiper arm does not include the post-coating step as described in the above (C), it is excellent in productivity and can provide a low-cost wiper arm.

4). Use of wiper arm The wiper arm of the present invention is used as a part of a wiper. Since the wiper arm of the present invention is excellent in light weight and appearance, it is suitable for a vehicle wiper, particularly an automobile wiper.

[Example 1]
Cold-rolled steel sheets having thicknesses of 0.8, 1.0, 1.2, 1.4, and 1.6 mm were prepared. The steel sheet had a yield strength (YP) of 340 N / mm ² and a tensile strength (TS) of 440 N / mm ² .
The steel plate was bent to obtain a wiper arm-shaped test piece shown in FIG. In FIG. 4, 40 is a test piece, 21 is the height at one end of the horizontal leg (5 mm), 22 is the height at the other end of the horizontal leg (20 mm), and 23 is the length of the horizontal leg. (500 mm), 11 is the width (10 mm) at one end of the ceiling, and 12 is the width (30 mm) at the other end of the ceiling. Further, as shown in FIG. 5A, the cross section of the test piece 40 of this example is 90 degrees in the bending angle of the lateral leg portion 20 and the bending portion of the edge portion 30. A 0.5 mm arc was formed. The cross-sectional shape was substantially similar along the longitudinal direction of the test piece, but the width 31 of the edge 30 was set to 4 mm and constant in the longitudinal direction of the test piece. The processing of the edge 30 in this example is also referred to as “L-shaped bending”.

The amount of displacement at the tip when a bending test was performed using this test piece 40 was determined by analysis. Specifically, when the test piece 40 is allowed to stand as shown in FIG. 6 with the ceiling portion 10 on the front side of the paper, the right edge of the paper is fixed, and a load of 400 N is applied in the direction of the arrow The amount of displacement at the tip of was determined. The analysis used FEM analysis software (LS-DYNA). In the analysis, the cold rolled steel sheet (having no plating layer and coating film) was used as a material.
It can be said that the smaller the amount of displacement, the higher the rigidity and the mechanical strength of the wiper arm. The analysis results are shown in FIG.

[Comparative Example 1]
The same cold rolled steel sheet as in Example 1 having a thickness of 1.6 mm was prepared. The steel sheet was bent and a test piece 40 was produced in the same manner as in Example 1. However, as shown in FIG. 5D, the cross-sectional shape was such that no edge was provided. The bending angle of the horizontal leg 20 was 90 degrees, and an arc having a radius of curvature of 0.5 mm was formed in the bent portion.
About the obtained test piece 40, it analyzed similarly to Example 1 and calculated | required the displacement amount of the front-end | tip part. The results are shown in FIG.

[Example 2]
Except that the cross-sectional shape of the test piece was changed to that shown in FIG. The bending angle of the edge 30 of this test piece was 180 degrees, and an arc having a curvature radius of 0.5 mm was formed inside the bent portion. Further, the bending angle of the lateral leg portion 20 was 90 degrees, and an arc having a curvature radius of 0.5 mm was formed in the bending portion 25. The processing of the edge 30 in this example is also called “U-bending”. This test piece was evaluated in the same manner as in Example 1. The results are shown in FIG.

[Example 3]
Test pieces 40 having different thicknesses were prepared in the same manner as in Example 1 except that the cross-sectional shape of the test piece was changed to that shown in FIG. 5C. The bending angle of the edge 30 of this test piece was 180 degrees, and no arc was formed inside the bent portion. Further, the bending angle of the lateral leg portion 20 was 90 degrees, and an arc having a curvature radius of 0.5 mm was formed in the bending portion 25. The processing of the edge 30 in this example is also referred to as “contact bending”. This test piece was evaluated in the same manner as in Example 1. The results are shown in FIG.

From FIG. 7, it is clear that even when the test piece 40 of Example 1 has a thickness of 1.2 mm and 1.4 mm, the displacement amount in the test is equal to or less than the displacement amount of the test piece of Comparative Example 1. . Therefore, the test piece 40 of Example 1 can make the thickness of a steel plate thinner than the steel plate of a comparative example. The weight of the thin test piece 40 is X, the weight of the test piece of Comparative Example 1 is Y, and the weight reduction rate of the test piece is obtained by the following equation (1) and shown in Table 1.
(Y−X) / Y × 100 (1)

Similarly, even when the test pieces 40 of Examples 2 and 3 have a thickness of 1.0 to 1.4 mm, it is clear that the displacement amount in the test is equal to or less than the displacement amount of the test piece of Comparative Example 1. is there. About these test pieces, the weight reduction rate was computed similarly to the above, and it put together in Table 1.
From Table 1, it is clear that the wiper arm of the present invention is excellent in lightness.
In addition, since the wiper arm of the present invention is present at a position where the end portion of the edge portion 30 is difficult to be seen by the driver, it is apparent that the appearance is hardly deteriorated even if red rust occurs due to corrosion.

  Since the wiper arm of the present invention is excellent in lightness and appearance, it is useful as a wiper part, particularly as an automobile wiper part.

The perspective view which shows an example of the wiper arm of this invention Sectional drawing of line ZZ in FIG. Sectional view of the wiper arm of the present invention made of painted steel plate Perspective view showing a wiper arm-shaped test piece Cross section of specimen Diagram showing bending test method Diagram showing the results of bending test analysis

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wiper arm 1a Wiper blade connection part 1b Rotating bearing part 2 Steel plate 3 Chemical conversion treatment layer 4 Primer coating film 5 Postcoat coating film 10 Ceiling part 11 Ceiling part width 12 Ceiling part width 20 Horizontal leg part 21 Horizontal leg part Height 22 Horizontal leg height 25 Arc 30 Edge 31 Edge width 35 Arc 40 Test piece α Bending angle β Bending angle t Thickness of wiper arm

Claims (8)

A wiper arm having a substantially U-shaped cross section having a ceiling portion and a pair of horizontal leg portions,
The wiper arm has an end formed by bending the end of the horizontal leg portion 180 degrees inward over the entire length in the longitudinal direction of the horizontal leg portion . The wiper arm is formed by processing a steel plate,
The wiper arm according to claim 1, wherein the steel plate is a primer steel plate having a primer coating formed on the surface of the steel plate before the processing.   The wiper arm according to claim 2, wherein the wiper arm has the primer coating on an inner surface thereof.   The wiper arm according to claim 2, wherein the wiper arm further has a post coat coating film formed after the processing on the primer coating film. The wiper arm is formed by processing a steel plate,
The said steel plate is a precoat steel plate which has the primer coating film formed in the steel plate surface before the said process, and the 2nd coating film formed in the primer coating film surface before the said process. The wiper arm described.   A wiper comprising the wiper arm according to claim 1. It is a manufacturing method of the wiper arm according to claim 1,
Preparing a primer steel sheet having a primer coating formed on the surface of the steel sheet;
A step of bending the primer steel plate,
A method for manufacturing a wiper arm, comprising: It is a manufacturing method of the wiper arm according to claim 1,
Preparing a pre-coated steel sheet having a primer coating formed on the surface of the steel sheet and a second coating formed on the primer coating;
A step of bending the pre-coated steel sheet,
A method for manufacturing a wiper arm, comprising:

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