JP4677804B2 - Method for evaluating squeezing property of press mold and test apparatus therefor - Google Patents
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Description
本発明は、プレス金型の型かじり性評価方法およびその試験装置に関する。 The present invention relates to a method for evaluating the galling property of a press die and a test apparatus therefor.
鋼板をプレス加工するプレス成形の現場において、たとえば引張り強さが590ＭＰａ以上というような高張力鋼板の使用割合が増加するのに伴い、製品の形状精度の低下、成形品不良率の増加や、金型寿命の低下、金型メンテナンス費用の増加が顕在化し、その一因である「型かじり」の発生が高張力鋼板の適用拡大に対する阻害要因としてクローズアップされてきた。このため、プレス金型についてはその材質ならびに表面処理のいずれにおいても硬度を増加させる方向などで対策が講じられている。とくに表面処理についてはＰＶＤ・ＣＶＤプロセスの適用により、種々の元素、成分の組み合わせが可能であり、処理メーカーによってさまざまな被膜が提案されている。 In press forming sites where steel sheets are pressed, for example, as the proportion of high-tensile steel sheets with a tensile strength of 590 MPa or more increases, the product shape accuracy decreases, the molded product defect rate increases, A decrease in mold life and an increase in mold maintenance costs have become apparent, and the occurrence of “mold galling”, one of the causes, has been highlighted as an impediment to the expansion of application of high-strength steel sheets. For this reason, measures are taken in the direction of increasing the hardness of the press mold in both the material and the surface treatment. Especially for surface treatment, various elements and components can be combined by applying a PVD / CVD process, and various coatings have been proposed by treatment manufacturers.
ところで、従来このような新しい材質や表面被膜の金型の実機における耐久性や型かじり性の評価手法としては、たとえば表面近くの微小部分の硬度や、被膜の密着性、靱性を示すスクラッチ試験など、被膜の物性そのものの試験が大部分である。また実機に近い条件での評価試験としては、動摩擦係数の推移や被加工材表面に発生する欠陥の程度による評価が中心となっている。しかし、動摩擦係数の推移を評価指標とした場合、金型表面の変化のみならず、被加工材表面の平滑化や油膜切れなどの被加工材側の変化に起因して動摩擦係数が大きく変化し、金型の評価として必ずしも適切ではない。 By the way, as a conventional evaluation method of durability and mold squeezing property in the actual machine of such a new material or surface coating mold, for example, a scratch test showing the hardness of a minute portion near the surface, the adhesion of the coating, and the toughness, etc. Most of the tests are the physical properties of the coating itself. In addition, evaluation tests under conditions close to those of actual machines are centered on evaluation based on the transition of the dynamic friction coefficient and the degree of defects generated on the surface of the workpiece. However, when the transition of the dynamic friction coefficient is used as an evaluation index, not only the mold surface changes, but also the dynamic friction coefficient changes greatly due to changes on the workpiece side such as smoothing of the workpiece surface and oil film breakage. It is not always appropriate as a mold evaluation.
また、円筒形やボタン形の曲面工具を用いる押しつけ摺動試験も行われているが、先端部の曲率などの工具の形状によって結果に大きなばらつきが発生し、信頼性に欠けるという問題点があった。
また表面処理した金型の場合、実機で型かじりの問題が発生するのは短くても数千ショット、長い場合には数万ショットという段階が普通であり、連続試験によって金型の性能比較をする場合、膨大な繰り返し試験を各金型ごとに実施する必要があり、大量の被加工材と長時間を必要とする。
In addition, although a pressing sliding test using a cylindrical or button-shaped curved tool has been performed, there is a problem in that the result varies greatly depending on the shape of the tool, such as the curvature of the tip, and is not reliable. It was.
In the case of a surface-treated mold, the problem of galling in an actual machine is usually a few thousand shots at the shortest and tens of thousands of shots at the longest. In this case, it is necessary to carry out a large number of repeated tests for each mold, which requires a large amount of work material and a long time.
本発明は、短時間のラボテストで結果の得られるプレス金型の型かじり性評価方法ならびにその試験装置を実現することを目的とする。 An object of the present invention is to realize a method for evaluating the galling property of a press die that can obtain a result in a short lab test, and a test apparatus therefor.
本発明のプレス金型の型かじり性評価方法は、平面を摺動面とするプレス金型に相当する試験ブロックを被加工材に相当する帯状の鋼板をはさんで対向ブロックに押しつけ、そのままこの鋼板を板面方向に引き抜くことを繰り返し、前記試験ブロックの摺動面を観察して、摺動回数の増加に伴う凝着発生状況の推移から前記プレス金型の型かじり性を評価することを特徴とし、望ましくは前記の凝着発生状況の推移が凝着発生面積率の変化であり、この凝着発生面積率は試験ブロックの摺動面の表面粗さ計による測定データから算出されるものであるか、試験ブロックの摺動面のＣＣＤカメラによる画像を処理して算出されるものであり、また、鋼板を引き抜くときの押しつけ力が，試験ブロックの摺動面の面圧で300〜1000ＭＰａの範囲である前記のプレス金型の型かじり性評価方法である。 The method for evaluating the galling property of a press die according to the present invention is to press a test block corresponding to a press die having a flat sliding surface against an opposing block with a strip-shaped steel plate corresponding to a workpiece sandwiched between them. Repeatedly pulling out the steel sheet in the direction of the plate surface, observing the sliding surface of the test block, and evaluating the die squeezing property of the press die from the transition of the state of occurrence of adhesion as the number of sliding increases. Preferably, the transition of the adhesion occurrence state described above is a change in the adhesion occurrence area ratio, and this adhesion occurrence area ratio is calculated from data measured by the surface roughness meter of the sliding surface of the test block. It is calculated by processing the image of the sliding surface of the test block with a CCD camera, and the pressing force when pulling out the steel plate is 300 to 1000 MPa in terms of the surface pressure of the sliding surface of the test block. Is in the range This is a method for evaluating the galling property of the press die.
また、本発明のプレス金型の型かじり性評価試験装置は、平面を摺動面とするプレス金型に相当する試験ブロックを保持する試験ブロックホルダと、この試験ブロックホルダの対向位置に対向ブロックを保持する対向ブロックホルダと、これら試験ブロックと対向ブロックを互いに押しつける押しつけ手段と、これら試験ブロックと対向ブロックの中間に挿入された帯状の鋼板を板面方向に引き抜く引き抜き手段と、前記試験ブロックの摺動面の表面状態を観察する観察手段とを有することを特徴とし、望ましくは試験ブロックが、摺動面が前記の鋼板を引き抜く方向と直角方向の平面であり、プレス金型に対応する表面処理が施され、平坦に仕上げられていることを特徴とする前記のプレス金型の型かじり性評価試験装置である。 Further, a die squeezing evaluation test apparatus for a press die according to the present invention includes a test block holder for holding a test block corresponding to a press die having a flat surface as a sliding surface, and an opposing block at an opposing position of the test block holder. A counter block holder for holding the test block, a pressing means for pressing the test block and the counter block against each other, a pulling means for pulling out the strip-shaped steel plate inserted between the test block and the counter block in the plate surface direction, and the test block An observation means for observing the surface state of the sliding surface, and preferably the test block is a surface corresponding to the press die, wherein the sliding surface is a plane perpendicular to the direction in which the steel plate is pulled out. The press squeezing property evaluation test apparatus for a press die described above, which is processed and finished flat.
本発明によれば、実機金型に相当する表面処理を施した小寸法の試験ブロックを使用して金型の型かじり性を評価できるので、実物の金型を使用してこれを損傷することなく、かつ長期間を要することなく判定ができるからプレス成形の現場においても作業効率が向上し、ひいては高張力鋼板の適用が拡大されて、プレスの生産性や品質も向上するという、優れた効果を奏する。 According to the present invention, it is possible to evaluate the galling property of a mold using a small-sized test block having a surface treatment equivalent to that of a real machine mold, and therefore, using a real mold, the damage can be damaged. Because it can be judged without requiring a long period of time, the work efficiency is improved even at the press forming site, and as a result, the application of high-strength steel sheets is expanded and the productivity and quality of the press are improved. Play.
本発明においては、プレス金型に相当する試験ブロックと、被加工材に相当する帯状の鋼板とが接触し摺動する面積を小さく設定することにより、従来の摺動試験装置の10〜100倍、すなわち被加工材の降伏応力以上を目安として、300ＭＰａ以上の接触面圧を印加できるようにして摺動試験を行い、型かじりを早期に発生させて短期間のうちに判定ができるようにした。 In the present invention, a test block corresponding to a press die and a strip-shaped steel plate corresponding to a work piece are in contact with each other and set to have a small area for sliding, thereby 10 to 100 times that of a conventional sliding test device. In other words, using the yield stress of the workpiece as a guideline, a sliding test was conducted so that a contact surface pressure of 300 MPa or more could be applied, and mold galling was generated early so that judgment could be made in a short period of time. .
本発明者らは、本発明に先立ち、まず高張力鋼板成形時の表面処理を施したプレス金型における型かじりの発生機構を推定した。種々のラボテストや実機に置ける損傷挙動を調査した結果、型かじり発生のプロセスは次の４段階によることがわかった。すなわち、
第１段階 潤滑層としての油膜の局部消失と境界潤滑部位への剪断応力の集中
第２段階 表面処理被膜の破壊、損耗による金属母材の露出
第３段階 露出部への被加工材の凝着と凝着部の発達
第４段階 凝着部による被加工材の掘り起こし（重かじり）発生
である。
Prior to the present invention, the present inventors first estimated the mechanism of the occurrence of die squeezing in a press die subjected to surface treatment at the time of forming a high-tensile steel plate. As a result of investigating the damage behavior that can be placed in various laboratory tests and actual machines, it was found that the process of mold galling is based on the following four stages. That is,
1st stage Local disappearance of oil film as lubrication layer and concentration of shear stress on boundary lubrication site 2nd stage Exposure of metal base material due to destruction and wear of surface treatment film 3rd stage Adhesion of work piece to exposed part The fourth stage of the development of the adhesion part is the occurrence of digging (heavy galling) of the workpiece by the adhesion part.
被膜損傷によって母材が露出した後は、金型母材と被加工材である鋼板との凝着性（親和性）の相違によって型かじりの程度が異なる。金型母材が同じであれば、表面処理被膜の型かじり抑制作用は、被膜が消失して金型母材が露出するまでの期間がもっとも重要な要因である。そして被膜が消失して母材が露出した箇所では、高い面圧のもとで比較的早く被加工材の凝着が発生するから、凝着部分がどの程度存在しているかで金型の損傷程度を表現できる。 After the base material is exposed due to film damage, the degree of mold galling differs depending on the adhesion (affinity) between the mold base material and the steel plate as the workpiece. If the mold base material is the same, the most important factor for the anti-galling action of the surface-treated film is the period from when the film disappears until the mold base material is exposed. And at the location where the coating disappears and the base material is exposed, the workpiece material adheres relatively quickly under high surface pressure. The degree can be expressed.
実機の金型においても、被加工材の凝着はレプリカ法による表面形状測定により非破壊で調査が可能であることが知られている。そこで本発明では金型表面への被加工材の凝着に着目し、凝着発生状況の推移、たとえば凝着発生面積率の変化を指標として比較追跡することで金型の型かじり性を定量的に的確かつ効果的に評価できるとの知見を得、本発明を完成するに至った。凝着発生面積は、３次元粗度計などの表面粗さ計による測定データから算出してもよいし、ＣＣＤカメラによる陰影データを画像処理して算出してもよい。 It is known that the adhesion of workpieces can be investigated nondestructively by measuring the surface shape by the replica method even in the actual mold. Therefore, in the present invention, focusing on the adhesion of the work material to the mold surface, the transition of the adhesion occurrence state, for example, the change in the area ratio of the adhesion occurrence is compared and tracked as an index to quantify the mold galling property. As a result, the present invention has been completed. The adhesion generation area may be calculated from measurement data obtained by a surface roughness meter such as a three-dimensional roughness meter, or may be calculated by performing image processing on shadow data obtained by a CCD camera.
図５は画像処理の一例を示す顕微鏡写真の模式図（スケッチ）で、枠の寸法は縦が0.8ｍｍ、横が4.0ｍｍである。斜線を施した部分が凝着発生部で、表面粗度にして5μｍ以上の凹凸が見られる。
観察する部分、範囲はとくに限定しないが、端部付近は不安定要素があるので、接触状況に片当たりが見られなければ、中心付近を任意に選定すればよい。
FIG. 5 is a schematic diagram (sketch) of a photomicrograph showing an example of image processing. The dimensions of the frame are 0.8 mm in length and 4.0 mm in width. The hatched part is the adhesion generating part, and the surface roughness is 5 μm or more.
The portion and range to be observed are not particularly limited, but there are unstable elements in the vicinity of the end portion. Therefore, if the contact state is not found, the vicinity of the center may be arbitrarily selected.
判定の閾値も任意に定めればよいが、摺動試験前の試験ブロックの表面をバフ研磨等によって鏡面仕上げしておくことを前提にすれば、表面粗度はＲa≦0.2μｍで凸部は皆無であるから、1.0〜5.0μｍ程度を判定の閾値とするのが妥当である。
つぎに短時間で凝着を発生させる促進試験としての試験条件を検討した。従来の連続試験や実機の操業においては、前記のプロセスの第１段階における油膜の局部消失の発生がきわめて低くなるように操業条件を調整している。実機では、微小な油膜消失によって引き起こされるわずかな損傷が蓄積して、数千ショットから数万ショットの後に目に見える不具合が発生するのである。したがって第１段階の発生確率を増加させることが型かじりを促進するキーポイントである。そこで試験ブロックの鋼板に対する接触面積を小さく設定することにより、従来の摺動試験装置の10〜100倍の、すなわち300〜1000ＭＰａの接触面圧を印加できるようにして油膜の消失を強制的に行うとともに、被膜損傷を促進する手法として、被加工材の同一個所を繰り返し摺動することとした。300ＭＰａ以上というのは前記したように被加工材の降伏応力程度以上という意味であり、300ＭＰａ未満ではこのような促進効果が得られない。上限の1000ＭＰａは設備仕様からくる限界である。
The threshold value of the determination may be arbitrarily determined. However, if it is assumed that the surface of the test block before the sliding test is mirror-finished by buffing or the like, the surface roughness is Ra ≦ 0.2 μm and the convex portion is Since there is nothing, it is appropriate to set the threshold value for determination at about 1.0 to 5.0 μm.
Next, the test conditions as an accelerated test for generating adhesion in a short time were examined. In conventional continuous tests and actual machine operations, the operation conditions are adjusted so that the occurrence of local disappearance of the oil film in the first stage of the process is extremely low. In the actual machine, slight damage caused by the disappearance of a minute oil film accumulates, and a visible defect occurs after thousands to tens of thousands of shots. Therefore, increasing the probability of occurrence of the first stage is a key point that promotes the galling. Therefore, by setting the contact area of the test block to the steel plate small, the oil film disappears forcibly by applying a contact surface pressure of 10 to 100 times that of the conventional sliding test device, that is, 300 to 1000 MPa. At the same time, as a technique for promoting film damage, the same part of the workpiece was slid repeatedly. As described above, 300 MPa or more means the yield stress or more of the workpiece, and if it is less than 300 MPa, such a promoting effect cannot be obtained. The upper limit of 1000 MPa is a limit derived from equipment specifications.
高張力鋼板の場合、条件にもよるが、１枚の被加工材で破断することなく10〜50回程度の繰り返し摺動が可能である。使用する被加工材は試験ブロックと繰り返し摺動させることにより、摺動の都度新しい被加工材に取り替える連続試験よりもはるかに早く金型の損傷が発生する。
図１は実施例のプレス金型の型かじり性評価試験装置を示す正面図で、１は試験ブロックＢを取り付けた前記の試験ブロックホルダ、２は試験ブロックＢの上下方向の対向位置に対向ブロックを保持する対向ブロックホルダ、３は試験ブロックホルダ１と対向ブロックホルダ２を相互に押しつける油圧式等の押しつけ手段、４は試験ブロックＢと対向ブロックの中間に挿入された鋼板Ｐを水平方向に引き抜いて摺動させる油圧シリンダ等の引き抜き手段、５は鋼板Ｐを掴むチャックである。
In the case of a high-strength steel plate, although depending on conditions, it can be repeatedly slid about 10 to 50 times without breaking with a single workpiece. By repeatedly sliding the work piece to be used with the test block, the mold damage occurs much faster than the continuous test in which the work piece is replaced with a new work piece at each sliding.
FIG. 1 is a front view showing a die squeezing evaluation test apparatus for a press die according to an embodiment, wherein 1 is the test block holder to which the test block B is attached, and 2 is an opposing block at the opposing position in the vertical direction of the test block B. 3 is a pressing means such as a hydraulic type that presses the
試験機はこの他に、図示しないが前記試験ブロックの表面状態を観察する３次元粗度計などの表面粗さ計、あるいはＣＣＤカメラ等の観察手段を備える。測定あるいは撮影は、被加工材が破壊に至る間でかなり頻繁に行う必要があり、その都度試験ブロックＢを取り出さなくてもよいような構成とすることが望ましい。例えば、試験ブロックＢと対向ブロック２とは図１の例では上下に対向させるが、これらの少なくとも一方が容易に対向位置から退避するようになっていることが好ましい。
In addition to this, the testing machine includes a surface roughness meter such as a three-dimensional roughness meter for observing the surface state of the test block, or an observation means such as a CCD camera, although not shown. Measurement or photographing needs to be performed quite frequently while the workpiece is broken, and it is desirable that the test block B not be taken out each time. For example, the test block B and the
試験ブロックＢと対向ブロックとは、いずれが上でも下でもかまわない。また、対向ブロックは対向ブロックホルダと一体でもよいし、試験機のラム、あるいはテーブルそのものを使用してもよい。さらに、対向ブロックとして別の試験ブロックを使用すれば、２回分の摺動試験を一度に行なうこともできる。
なお、本発明の試験装置は図１に例示した上下方向に加圧する横型のものに限定されるわけではなく、縦型にすることも可能である。
Either the test block B or the opposing block may be above or below. Further, the opposing block may be integrated with the opposing block holder, or a test machine ram or the table itself may be used. Furthermore, if another test block is used as the opposing block, two sliding tests can be performed at a time.
In addition, the test apparatus of this invention is not necessarily limited to the horizontal type which pressurizes in the up-down direction illustrated in FIG. 1, and can also be made into a vertical type.
図２は実施例の試験装置における試験ブロックＢを示す斜視図で、Ｓはその頂部の摺動面である。また図３はこの試験ブロックＢを試験機に取り付けるための試験ブロックホルダ１を示す斜視図で、11は試験ブロックＢを固定するためのスペーサ、12は試験機に取り付けるためのボルト孔である。
試験ブロックはプレス金型に相当するものであるから、鋼板に接する摺動面にプレス金型と同様の表面処理が施されていることはいうまでもない。摺動面は平面である。端部には面取りが施されている場合もある。この例では試験ブロックの上面は中央の高い左右対称の３つ折れ平面であり、中央の部分が摺動面で、研磨加工により平坦に、かつ水平に仕上げられている。従来のように円筒形やボタン形の曲面工具による摺動試験では線接触状あるいは点接触となって、接触面圧を正確に規定することができない上、接触面圧が高いと被加工材に試験ブロックが食い込んだ状態で引き抜きが行なわれることもあるので、試験ブロックの被膜に発生する剪断応力も不安定となるなど、接触部分の形状が評価結果に大きく影響してしまうが、本発明のように摺動面が平面であればそのような問題がない。
FIG. 2 is a perspective view showing a test block B in the test apparatus of the embodiment, and S is a sliding surface of the top portion thereof. FIG. 3 is a perspective view showing the
Since the test block corresponds to a press die, it goes without saying that the same surface treatment as that of the press die is applied to the sliding surface in contact with the steel plate. The sliding surface is a flat surface. The end may be chamfered. In this example, the upper surface of the test block is a three-fold plane with high symmetry at the center, and the center portion is a sliding surface, which is finished flat and horizontally by polishing. In conventional sliding tests with cylindrical or button-shaped curved tools, it becomes a line contact or point contact, and the contact surface pressure cannot be accurately defined. Since the test block may be pulled out, the shape of the contact part greatly affects the evaluation result, for example, the shear stress generated in the test block film becomes unstable. If the sliding surface is flat, there is no such problem.
本発明では、この試験ブロックを、被加工材すなわちプレス作業におけるワークに相当する帯状の鋼板をはさんで上下方向に対向ブロックに押しつけ、最初以外は塗油せずにこの鋼板を水平方向に引き抜いて繰り返して摺動する。繰り返し摺動することにより油膜層は徐々に薄くなり、油膜切れを起こすと試験ブロックと鋼板が直接接触して摩擦係数、すなわち引き抜き力が急増するので試験が継続できなくなる場合があるから、被加工材や試験ブロックの種類、摺動条件に応じて10〜50回の間で鋼板を塗油した新しいものに交換する。塗油は実機における塗油に合わせて行なうので、通常の防錆油を通常の程度に塗布する。初回の摺動で余分の油膜層は系外に排出されるから、塗油量についてはあまり厳密に管理する必要はない。また、無潤滑のドライプレス用の金型を試験対象とする場合などは、塗油を行なわなくてよい。 In the present invention, this test block is pressed against the opposing block in the vertical direction across the work piece, that is, the strip-shaped steel plate corresponding to the workpiece in the pressing operation, and this steel plate is pulled out horizontally without oiling except for the first. And slide repeatedly. By repeatedly sliding, the oil film layer gradually becomes thin, and if the oil film breaks, the test block and the steel plate come into direct contact and the coefficient of friction, that is, the pulling force increases rapidly, so the test may not be continued. Replace with a new steel plate oiled between 10 and 50 times depending on the type of material, test block and sliding conditions. Since the oil coating is performed in accordance with the oil coating in the actual machine, normal rust preventive oil is applied to a normal level. Since the excess oil film layer is discharged out of the system by the first sliding, it is not necessary to strictly control the oil coating amount. In addition, when a non-lubricated dry press mold is used as a test object, it is not necessary to apply oil.
摺動面Ｓは鋼板を摺動させる方向と直角方向に細長く伸びており、その幅は0.5ｍｍ以上5.0ｍｍ未満ときわめて細い。これは本発明の摺動試験が通常の摺動試験（10〜100ＭＰａ）よりもはるかに高い300〜1000ＭＰａ程度の接触面圧を必要とするためである。
図４は本発明の摺動試験における接触面積を説明する説明図で、Ｐは鋼板、矢印は摺動方向である。鋼板Ｐの幅を10ｍｍとし、摺動面の幅をたとえば1ｍｍとすれば斜線を施した接触部の面積は10ｍｍ2、すなわち0.1ｃｍ2であるから、通常の試験機の能力である約300〜1000ｋｇｆの押しつけ力で、300〜1000ＭＰａという、大きな面圧が実現できる。
The sliding surface S is elongated in a direction perpendicular to the direction in which the steel sheet is slid, and its width is extremely thin, 0.5 mm or more and less than 5.0 mm. This is because the sliding test of the present invention requires a contact surface pressure of about 300 to 1000 MPa, which is much higher than the normal sliding test (10 to 100 MPa).
FIG. 4 is an explanatory view for explaining the contact area in the sliding test of the present invention, P is a steel plate, and an arrow is a sliding direction. If the width of the steel plate P is 10 mm and the width of the sliding surface is 1 mm, for example, the area of the contact portion with hatching is 10 mm 2 , that is, 0.1 cm 2. With a pressing force of 1000 kgf, a large surface pressure of 300 to 1000 MPa can be realized.
本発明では上記の装置を使用し、前記したような摺動を繰り返しながら、たとえば鋼板を交換する毎に摺動面の表面状態を観察して、摺動回数と凝着発生状況の推移、とくに凝着発生面積率の変化を指標として利用することにより、前記プレス金型の型かじり性を定量的に評価する。 In the present invention, using the above-mentioned apparatus, while repeating the sliding as described above, for example, by observing the surface state of the sliding surface every time the steel plate is replaced, the transition of the number of sliding times and the state of occurrence of adhesion, especially By using the change in the adhesion generation area ratio as an index, the galling property of the press die is quantitatively evaluated.
被加工材である鋼板として冷延鋼板（引張り強度780ＭＰａ）、板厚2.0ｍｍのものを10ｍｍ幅に剪断し、エッジ部のかえりを除去した後、溶剤脱脂、洗浄したものを用意し、一方の試験ブロックとしてはダイス用合金工具鋼ＳＫＤ１１を母材としてＣＶＤ法により炭化チタン被膜を6.0μｍ厚に形成し、ラッピング仕上げしたものを用意した。
鋼板には摺動試験直前に一般防錆油を両面にスポンジで塗布し、ペーパーで拭き取って使用した。
Cold-rolled steel sheet (tensile strength 780 MPa) as the work material, shear thickness 2.0 mm, sheared to 10 mm width, removed the burr at the edge, then prepared solvent degreased and washed, The test block was prepared by forming a titanium carbide coating with a thickness of 6.0 μm by CVD using a die alloy tool steel SKD11 as a base material and lapping finish.
The steel sheet was coated with a general rust preventive oil on both sides just before the sliding test and wiped with paper.
試験ブロックと鋼板を試験機にセットし、繰り返し摺動を行なった。垂直方向の押しつけ力を7.84ｋＮ（800ｋｇｆ）に設定し、室温のまま、引き抜き速度200ｍｍ／ｓで鋼板を引き抜き、引き抜き荷重と押しつけ荷重の変化を記録した。1本の鋼板で10回連続に引き抜きを行い、10回毎に鋼板を新しいものに交換しながら、100回まで試験を行なった。10回摺動毎に試験ブロックの摺動面を３次元粗度計によって調査し、凝着発生面積率を求めた。 The test block and the steel plate were set in a testing machine and repeatedly slid. The vertical pressing force was set to 7.84 kN (800 kgf), the steel sheet was pulled out at a pulling speed of 200 mm / s while keeping the room temperature, and changes in the pulling load and the pressing load were recorded. The test was carried out up to 100 times with one steel plate being continuously pulled out 10 times and replacing the steel plate every 10 times with a new one. The sliding surface of the test block was investigated with a three-dimensional roughness meter every tenth sliding, and the adhesion area ratio was determined.
図６はこの実施例における動摩擦係数および凝着発生面積率の推移を示すグラフで、横軸は摺動回数、縦軸（左）および黒丸が動摩擦係数、縦軸（右）および白丸が凝着発生面積率である。
摺動回数40回あたりから凝着の発生が認められた。それとともに動摩擦係数の値が上昇したが、そのばらつきが大きく、動摩擦係数の変化からでは型かじり性の進行傾向を把握することは困難である。これに対して凝着面積率の方は凝着発生状況に対応して値を漸増させている。型かじり性の判定指標として凝着発生面積率を使用することが、試験の信頼性において優れていることがわかる。
FIG. 6 is a graph showing the transition of the dynamic friction coefficient and the adhesion generation area ratio in this example. The horizontal axis is the number of sliding times, the vertical axis (left) and the black circle are dynamic friction coefficients, and the vertical axis (right) and the white circle are adhesions. It is the generation area rate.
Adhesion was observed from around 40 slides. At the same time, the value of the dynamic friction coefficient increased. However, the variation was large, and it was difficult to grasp the progress tendency of the mold galling property from the change of the dynamic friction coefficient. On the other hand, the value of the adhesion area ratio is gradually increased in accordance with the state of occurrence of adhesion. It can be seen that it is excellent in the reliability of the test to use the adhesion generation area ratio as an index for determining the galling property.
１ 試験ブロックホルダ
２ 対向ブロックホルダ
３ 押しつけ手段
４ 引き抜き手段
５ チャック
11 スペーサ
12 ボルト孔
Ｂ 試験ブロック
Ｐ 鋼板
Ｓ 摺動面
DESCRIPTION OF
11 Spacer
12 Bolt hole B Test block P Steel plate S Sliding surface
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| JP5993321B2 (en) * | 2013-02-12 | 2016-09-14 | 株式会社神戸製鋼所 | Evaluation method of adhesion resistance of molds |
| JP6198244B2 (en) * | 2014-08-21 | 2017-09-20 | 株式会社神戸製鋼所 | Evaluation method of mold resistance |
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| JP2003245738A (en) * | 2002-02-22 | 2003-09-02 | Nippon Steel Corp | Die material for plate press-forming in warm forming or hot forming |
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| JPH06138020A (en) * | 1992-10-26 | 1994-05-20 | Kawasaki Steel Corp | Sliding test method |
| JPH06304679A (en) * | 1993-04-26 | 1994-11-01 | Kyocera Corp | Jig for working |
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