JP4259337B2 - Performance evaluation method and equipment for lubricant for forging - Google Patents

Description

  The present invention relates to a method and apparatus for evaluating the performance of a lubricant used in forging a metal material.

  Lubricants used in forging are extremely important for reducing the coefficient of friction between the material and the die and preventing direct contact (seizure). It is evaluated whether the lubricating performance matches, and the optimum one is selected and used. Even during forging operations, the performance may change depending on the temperature, humidity conditions, etc., so the performance may be evaluated during the forging operation.

  As an evaluation method of the lubrication performance performed at the time of actual forging, there are a ring compression test method, a front extrusion method, a rear extrusion method, and the like. However, these evaluation methods have advantages and disadvantages. A method has been proposed.

  In this proposal, a cylindrical metal piece is placed on a funnel-shaped die, a load is applied under the application of a lubricant, a spike is formed according to the die shape, and the formed metal piece is projected from the direction opposite to the pushing direction. The performance of the lubricant is evaluated on the basis of the load required to achieve a certain indentation amount, the height of the formed spike, and the load required for protrusion.

  This method determines the superiority or inferiority of the lubrication performance from the dimensions of the spike after extrusion and the required load, and the surface area expansion ratio (the ratio of the surface area including the new surface generated by forging to the old surface area) is relatively high. Suitable for lubrication performance evaluation under large forging conditions.

However, with this lubricating performance evaluation method, it is difficult to determine the friction coefficient of the lubricant. The method for evaluating the lubrication performance should essentially know the friction coefficient of the lubricant, and does not require the surface area enlargement ratio, spike height or load values. However, when various lubricants are applied to test pieces that are deformed by forging (hereinafter referred to as test pieces) and the performance of the lubricant is evaluated by pressurizing each test piece, the friction coefficient and the surface area expansion ratio are closely related. If the friction coefficient is different, the fluidity of the material changes, the shape changes, and the surface area enlargement ratio changes each time. Control example, when the performance evaluation of a lubricant friction coefficient as a parameter, but the shape of post-compression must be the same, also change the shape of the test piece lubricant funny Warutabi, the surface area magnification ratio However, it is extremely difficult to obtain the friction coefficient while suppressing the fluidity of the material.

For this reason, if the influence of the surface area enlargement ratio and the friction coefficient are to be investigated, it is necessary to investigate the correlation in different tests, which is disadvantageous in terms of time and cost, and it is possible to easily evaluate the lubricant. There is a bug that you can not.
Japanese Patent Laid-Open No. 5-7969 (see FIG. 3, claim 1, paragraph number [0009])

  An object of the present invention is to solve the problems associated with the above-described conventional technology, and it is possible to quantitatively evaluate the performance of the lubricant without affecting the surface area enlargement ratio, the test is simple, and the time is cost-effective. In addition, it is easy to determine the deterioration of the lubricant in the actual forging process.

The performance evaluation method for a cast lubricant according to the present invention that achieves such an object provides a test piece in which a lubricant is applied to the surface in a storage space provided in an outer peripheral holding member. When the end surface is supported by the support member and the end surface on the opposite side of the support member is pressurized by the pressure member , a molding load is applied to a position other than the center of the test piece at the tip of the pressure member, and the test piece is It is characterized by evaluating the characteristics of the lubricant by extruding backward in the outer periphery holding member, comparing the height difference of the deformed portion of the test piece generated by the backward extrusion with the characteristics of the lubricant obtained in advance. .

The cast lubricant performance evaluation apparatus according to the present invention is supported by an outer peripheral holding member in which a test piece is provided in an internal storage space, a support member that supports one end surface of the test piece, and a support member of the test piece. A pressure member that pressurizes the opposite end surface, and a pressure means that pressurizes the pressure member and applies a molding load to the test piece, so that the lubricant to be tested is applied to the surface by the pressure means. Applying a molding load to a position other than the center of the test piece in the applied state, the height difference of the deformed portion caused by pushing the test piece backward in the outer peripheral holding member is determined in advance as the characteristics of the lubricant. The characteristics of the lubricant are evaluated by comparison.

In the invention configured as described above, the eccentric position of the test piece is pressed by the pressure member and pushed backward while the periphery of the test piece is constrained by the outer peripheral holding member. When the eccentric position of the test piece is pressed and pushed backward, the surplus of the test piece removed by the pressurizing member generates a deformed portion, but the surface area magnification of each portion in the deformed portion is the same. Thus, by measuring the difference in height between the deformable portion arising here, when compared with the properties of previously determined lubricants, without being affected by changes in the surface area magnification, it is possible to evaluate the characteristics of the lubricant.

  Further, the test is simple, which is advantageous in terms of time and cost, and it is possible to easily determine the deterioration of the lubricant in the actual forging process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a lubricant performance evaluation apparatus will be described, and the lubricant performance evaluation method performed using the apparatus will be described. Here, FIG. 1 is a perspective view of a lubricant performance evaluation apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line 2-2 of FIG.

  The present embodiment will be briefly described. The test piece W coated with the lubricant to be tested on the surface is subjected to pressure deformation, and the amount of deformation of the deformed portion H is compared with the characteristics of the lubricant obtained in advance. As shown in FIGS. 1 and 2, the outer peripheral holding member 2 having a through hole 1 as a storage space in which the test piece W is stored, and a support member that supports the lower end surface of the test piece W. 3, the pressurizing member 4 is press-fitted from the through-hole 1, and the test piece W is pushed backward in the outer peripheral holding member 2 to form the deformed portion H. Here, the deformation amount of the deformation portion H includes not only the physical deformation amount of the deformation portion H but also a load caused by the deformation. Further, the lubricant is a phosphoric acid lubricant and is obtained by changing the blending ratio of various additives (for example, molybdenum).

  Further details will be described. The test piece W itself may have any shape, but in order to perform a quick test, both end faces are formed parallel and smooth, and there is a gap between the inner peripheral face of the outer peripheral holding member 2. A thing as small as possible is preferable. With such a test piece W, the deformed portion H can be immediately formed by pressurizing the pressure member 4, the deformation amount can be easily understood, and a rapid test can be performed. In the present embodiment, a columnar body having a rectangular cross section perpendicular to the axis is used, but a cylindrical or polygonal shape may be used.

  The outer periphery holding member 2 is held in a fixed position by a restricting plate 10 that restricts floating on a base (not shown), and a through hole 1 into which a test piece W is inserted is formed in the central portion. A support member 3 (see FIG. 2) is closely fitted to the lower portion of the through hole 1, and a pressure member 4 is provided on the upper portion.

  The pressure member 4 is a quadrangular prism corresponding to the test piece W of a rectangular columnar body, and a fluid pressure operation is applied to the test piece W by applying a molding load F to the upper end via a molding load measuring member 7 described later. The pressurizing means 5 is connected.

  The lower end portion of the pressure member 4 is a tapered portion 4a. The reason why the lower end portion is the tapered portion 4a is that the surface pressure can be widely applied to the test piece W, and the rearward extrusion can be smoothly performed.

  The support member 3 has a cross-sectional shape similar to the cross-sectional shape perpendicular to the axis of the through-hole 1 and has a substantially quadrangular prism shape as a whole, and supports the test piece W during pressurization from below. A pressurizing means 6 that presses the test piece W upward and discharges it is connected via a molding load measuring member 7.

In particular, in the present embodiment, the amount of deformation of the deformed portion H (see FIG. 5 ) caused by the pressure member 4 pressing the test piece W and pushing backward is compared with the previously determined characteristics of the lubricant. Evaluate the properties of the lubricant. The amount of deformation may be the amount of deformation of a predetermined portion of the test piece W, but it is easy to judge from the height difference (h1−h2) in the deformed portion H of the test piece W.

Therefore, in the present embodiment, the pressing member 4 applies a molding load F to a position other than the center of the test piece W, pushes the test piece W backward in the outer peripheral holding member 2, and forms the deformed portion H of the test piece W. A height difference (h ₁ −h ₂ ) is generated. This is because when the center is pressed instead of the eccentric position, the test piece W is uniformly deformed, and the height difference (h ₁ −h ₂ ) does not occur in the deformed portion H.

  The deformation amount of the deformation portion H is not limited to the height difference, but may be a molding load F obtained by pressurizing and deforming the test piece W. Depending on the lubricant to be tested, there is a possibility that the difference in height does not occur or the measurement cannot be performed because the difference is small, but even in such a case, the pressurizing means is provided on the upper end of the pressurizing member 4 and the lower end of the support member 3. The molding load measuring members 7 and 8 constituted by a load cell or the like for measuring the molding load F applied by 5 and 6 are provided, the molding load F is detected by these molding load measuring members 7 and 8, and the detected molding load is detected. If F is compared with the molding load obtained separately, the characteristics of the lubricant can be evaluated.

  In the figure, “9” is an exclusion plate for pulling the pressure member 4 away from the test piece W when the pressure member 4 is pulled out from the test piece W.

  Next, a method for evaluating the performance of the lubricant will be described.

  The evaluation of the performance of the lubricant is essentially performed only if the friction coefficient of the lubricant is known. Therefore, the evaluation method of this embodiment is also an evaluation based mainly on the friction coefficient.

<Evaluation by measurement of friction coefficient>
First, for each friction coefficient of the lubricant to be tested by experiment or FEM analysis, the relationship between the pressing stroke of the pressure member 4 and the deformation amount of the deformed portion H, that is, the height difference (h ₁ −h ₂ ) is shown. A reference line is obtained in advance and displayed in a graph. FIG. 7 is a graph showing reference lines obtained for lubricants having different friction coefficients.

For example, as shown in FIG. 7, m = 0.05, m = 0.09, m = 0 for three types of phosphoric acid lubricants A, B, and C having different friction coefficients (m) depending on the blending of additives. A reference line indicating the relationship between the indentation stroke and the height difference (h ₁ −h ₂ ) is obtained for each friction coefficient of .15 by experiment or FEM analysis.

  Next, for example, a test for obtaining a height difference is performed. 3 shows the relationship between the pressure member and the test piece, (A) is a cross-sectional view before pressure, (B) is an enlarged cross-sectional equivalent view taken along line BB of (A), and FIG. 4 is a pressure member. FIG. 5 is a cross-sectional view showing a state of the test piece after being pressurized, and FIG. 6 is a cross-sectional view showing a state in which the pressure member is pulled out from the test piece.

  As shown in FIG. 3A, the test is started by putting the test piece W into the through hole 1 of the outer peripheral holding member 2 that is a storage space and supporting it by the support member 3. The test piece W in the through hole 1 is set in a state where the periphery is substantially in contact with the inner side surface of the through hole 1.

Pressure member 4, as shown in FIG. 3 (B), the center O ₂ of the pressure member 4 with respect to the center O ₁ of the specimen W is set at a position eccentric by a predetermined amount. For example, it is assumed that the eccentric amount in the horizontal direction is δ ₁ and the eccentric amount in the vertical direction is δ ₂ . As a result, when pressure is applied by the pressure member 4, a wide region R ₁ and a narrow region R ₂ are generated around the pressure member 4 between the pressure member 4 and the inner surface of the through hole 1. It will be.

According to experiments, a narrow region R ₂ and the ratio of the wider region R ₁ is 1: 5 to 1: has been found to be about 4 is preferred. For example, when an experiment for measuring the height difference (h ₁ -h ₂ ) of the deformed portion H with respect to the indentation stroke is performed using SCr420 as the test piece W, as shown in FIG. Although a difference was obtained, in the case of 1: 4, a significant difference in height was obtained. From this point, the ratio is more preferably 1: 4.

  Then, as shown in FIG. 4, the pressing member 4 is moved downward by the pressing means 5, and the test piece W is pressed with the molding load F. Since the pressurizing member 4 has a tapered portion 5a formed in the lower portion, a large surface pressure acts on the test piece W, and the surplus wall of the test piece W has a frictional resistance along the inner side surface of the outer periphery holding member 2. It is pushed backward while being affected.

Pressure member 4, because they are set at a position eccentric to the center of the test piece W, the excess thickness of the test piece W, which is eliminated by the pressure member 4, flows through the wide regions R ₁ and the narrow region R ₂ Then, a deformed portion H as shown in FIG. 5 is formed. This surplus is easy to flow in the wide region R ₁ , difficult to flow in the narrow region R ₂ , and the flow state varies depending on the friction coefficient of the lubricant, so that each of the surplus areas formed in the wide region R ₁ and the narrow region R ₂ A height difference (h ₁ −h ₂ ) occurs in the deformed portion H. Further, since the test piece W is only surrounded by the outer periphery holding member 2 and there is nothing that regulates the flow deformation of the test piece W, the surface areas of the regions R ₁ and R ₂ with respect to the pushing stroke are determined. The magnification is the same. That is, with respect to the surplus wall flowing through the wide region R ₁ and the narrow region R ₂ , the surface area expansion ratio with respect to the indentation stroke can be offset or ignored, and the friction coefficient of the lubricant applied to the test piece W is It can be expressed as a parameter of the height difference (h ₁ −h ₂ ) with respect to the indentation stroke.

The height difference (h ₁ −h ₂ ) to be measured is preferably obtained from the difference between the maximum height and the minimum height at the deformed portion H. This is because the height difference is not only easy to measure, but also preferable in terms of measurement accuracy, and it is easy to determine whether the lubricant is good or bad.

  Here, it verified about the relationship between an indentation stroke and a surface area expansion rate. Three types of lubricants having a known friction coefficient (m) are applied to the test piece W, housed in the outer peripheral holding member 2, and a pressing stroke when pressurized with a molding load F using the pressure member 4; The relationship of the surface area expansion rate of each test piece W was examined. As a result, the product shown in FIG. 9 was obtained.

  As is apparent from FIG. 9, each of the lubricants having a friction coefficient (m) of m = 0.07, m = 0.09, and m = 0.2 has substantially the same surface area expansion ratio for each indentation stroke. became. That is, if the device configured to push out eccentrically and backwardly is used, the surface area expansion ratio with respect to the pressing stroke of the pressing member can be offset or ignored.

Therefore, when the relationship between the indentation stroke and the height difference (h ₁ -h ₂ ) obtained in the indentation test of the pressing member 4 is collated with the graph showing the relationship between the indentation stroke and the height difference displayed in advance shown in FIG. The characteristics of the lubricant, in particular, the coefficient of friction can be determined. For example, if the line segment indicating the relationship between the indentation stroke and the height difference (h ₁ −h ₂ ) obtained by the test is “dashed line a” shown in FIG. 7, m = 0.05 and m = 0.09. Therefore, the friction coefficient of the tested lubricant is m = 0.07.

As shown in FIG. 6, the test piece W thus deformed by pressure is pushed out from the inside of the through hole 1 of the outer peripheral holding member 2 by the upward movement of the lower support member 3 by the operation of the pressurizing means 6. Accordingly, the pressurizing member 4 also moves upward by the operation of the pressurizing means 5 and tries to come out of the test piece W. In this case, the test piece W comes into contact with the lip of the through hole 9 a provided in the exclusion plate 9, and the pressure member 4 comes out of the test piece W. In this way, the lubricant evaluation test is completed.

  However, since it is not preferable in terms of workability to measure the height difference in an actual factory line where mass production is performed, it is preferable to set a certain standard for the height difference. In particular, the characteristics of the lubricant may change depending on the time of day, and since the type of lubricant that is actually used in the factory has been specified, the upper limit value of the height difference of the lubricant is set in advance. If it is determined, the lubricant can be easily evaluated, and convenience is improved.

  As this standard, the upper limit of the height difference is determined using a lubricant containing an additive that has damaged the mold in a mass production trial. In other words, if it exceeds the upper limit, the lubricant may not be able to exhibit its original performance, and it becomes clear that it needs to be replaced.

  FIG. 10 is a table showing the results of measuring the height difference in the indentation stroke using the lubricant that damaged the mold in the actual forging process. The vertical axis shows the height difference, and the test date of this height difference is shown. There is a difference in height difference between A and B. As described above, the difference in height between the test dates A and B is considered to be due to various conditions such as temperature and use frequency. In any case, if the upper limit of the height difference is exceeded, the friction coefficient of the lubricant is exceeded. However, the lubricant does not exhibit its original performance, and in some cases, the mold may be damaged. According to the results of the experiment, the upper limit of the height difference is 8 mm, and beyond this, the lubricant did not exhibit its original performance.

In the test, the height difference (h ₁ −h ₂ ) may not be obtained or may be small even when the pressing member 4 is eccentrically pressed. In such a case, the superiority or inferiority of the lubricant can be evaluated by measuring the molding load F with the molding load measuring members 7 and 8 provided on the pressure member 4 and the support member 3. In the course of the test, it was found that there was a difference in the molding load when the friction coefficient of the lubricant was different.

  FIG. 11 is a graph showing the results of actual measurement of the relationship between the extrusion trolley and the molding load F for the lubricant that was used in actual forging and obtained good results. Since the test according to the present embodiment is backward extrusion molding, when the molding load F is added, the molding load F becomes a steady state from a certain point in time, but the friction coefficient of each lubricant is different in this steady state as well. Is different. Since this steady state is reached by a predetermined indentation stroke, the molding load F corresponding to the indentation stroke is measured during the test, and this measured value is compared with a good lubricant value shown in the graph of FIG. Then, the quality of the lubricant can be determined. That is, when the lubricating oil to be tested is applied to the test piece W and the indentation stroke is 10 mm, the value of the molding load F measured by the molding load measuring members 7 and 8 is compared with the graph of FIG. When the measured value of the lubricant is in agreement with the graph of FIG. 11, it can be seen that the lubricant is a preferable lubricant.

Therefore, even if the height difference (h ₁ −h ₂ ) cannot be obtained in the test, the superiority or inferiority of the lubricant can be determined by measuring the molding load F with the molding load measuring members 7 and 8. it can.
<Evaluation by releasability>
The superiority or inferiority of the lubricant can also be determined by measuring the load when the test piece W is extracted from the through hole 1 of the outer periphery holding member 2. FIG. 12 shows the result of measuring the protruding load that protrudes the test piece from the outer peripheral holding member after the pressing member 4 is pushed into the test piece W using the A, B, and C types of lubricants with a pushing stroke of 20 mm. It is a graph.

  For example, when the pressure member 4 is pushed into the test piece W by 20 mm and the test piece W protrudes from the outer periphery holding member 2 from this point, the value measured by the forming load measuring members 7 and 8 is 5 tons. If it is, since it is comparable to the lubricant C to which phosphoric acid is added, it can be evaluated that it is a preferable lubricant with respect to releasability. That is, the superiority or inferiority of the lubricant can also be determined by releasing the load when the test piece W is extracted from the through hole 1 of the outer periphery holding member 2.

  As described above, the test according to the present embodiment can evaluate the characteristics of the lubricant without being affected by the change in the surface area enlargement ratio, and is advantageous in terms of time and cost even in the actual forging process. Although the deterioration of the lubricant can be evaluated, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.

For example, in the above embodiment, the characteristics of the lubricant are evaluated from the height difference (h ₁ -h ₂ ) of the deformed portion H. However, in the actual forging process, it is difficult to measure the height difference as an actual problem. is there. Therefore, if the friction coefficient (m) is different, the molding load F is also different, so a graph showing the relationship between the molding load F and the height difference (h ₁ -h ₂ ) or the friction coefficient m is created by prior measurement or FEM analysis. Then, the measured molding load F may be compared with a value such as a graph to determine the superiority or inferiority of the lubricant.

  Moreover, in the said embodiment, although the load cell is used for the measurement of the shaping | molding load F and a protrusion load, you may use another method, such as using a strain gauge.

  The forging lubricant performance evaluation method and apparatus according to the present invention relates to a lubricant used when forging a crankshaft or a camshaft of an automobile engine, and its performance is simply tested and evaluated. Is suitable.

1 is a perspective view of a lubricant performance evaluation apparatus according to an embodiment of the present invention. It is sectional drawing which follows the 2-2 line of FIG. The relationship between a pressurizing member and a test piece is shown, (A) is a cross-sectional view before pressurization, and (B) is an enlarged cross-sectional equivalent view taken along line BB in (A). It is sectional drawing of the state which pushed the pressurization member into the test piece. It is sectional drawing which shows the state of the test piece after pressing. It is sectional drawing of the state which pulled out the pressurization member from the test piece. It is a graph which shows the reference line calculated | required about the lubricant from which a friction coefficient differs. It is a graph which shows the relationship between a punch stroke and a forming load measured in the apparatus of the embodiment of the present invention. It is a graph which shows the relationship between an indentation stroke and a surface area expansion rate. It is a table | surface which shows the pushing stroke and height difference of a predetermined | prescribed lubricant. It is a graph which shows the relationship between the extrusion trolley of a predetermined lubricant, and a molding load. It is a graph which shows the result of having measured the protrusion load which protrudes a test piece from an outer periphery holding member.

Explanation of symbols

1 ... Through hole (storage space),
2 ... outer periphery holding member,
3 ... support member,
4 ... Pressure member,
4a ... taper part,
5, 6 ... pressurizing means,
7, 8 ... molding load measuring member,
h ₁ -h ₂ ... height difference,
F: Molding load,
H ... Deformation part,
W: Test piece.

Claims (7)

A test piece with a lubricant applied to the surface is provided in the storage space provided in the outer periphery holding member, one end surface of the test piece is supported by a support member, and the opposite end surface of the support member is added. When applying pressure by the pressure member , a molding load is applied to a position other than the center of the test piece at the tip of the pressure member, the test piece is extruded backward in the outer periphery holding member, and the test piece generated by the rear extrusion is A method for evaluating the performance of a forging lubricant, wherein the difference in height of the deformed portion is compared with the characteristics of the lubricant obtained in advance to evaluate the characteristics of the lubricant. The forging lubricant performance evaluation method according to claim 1 , wherein the height difference is a difference between a maximum height and a minimum height . 3. The method for evaluating the performance of a forging lubricant according to claim 1 , wherein the height difference of the deformed portion is a value obtained for a predetermined amount of indentation stroke of the pressure member . The minimum width and the maximum width of the gap width between the side surface of the pressure member and the inner side surface of the storage space in which the test piece formed on the outer peripheral holding member is stored is a ratio of 1: 4 to 1: 5. A method for evaluating the performance of a forging lubricant according to any one of claims 1 to 3 . An outer periphery holding member in which a test piece is provided in an internal storage space;
  A support member for supporting one end surface of the test piece;
  A pressurizing member that pressurizes the opposite end surface supported by the support member of the test piece;
  Pressurizing means for pressurizing the pressurizing member and applying a molding load to the test piece;
  Have
  A deformed portion generated by applying a molding load to a position other than the center of the test piece in a state where the lubricant to be tested is applied to the surface by the pressurizing means, and pushing the test piece backward in the outer peripheral holding member. A forging lubricant performance evaluation apparatus, wherein the difference in height is compared with the previously determined characteristics of the lubricant to evaluate the characteristics of the lubricant. The forging lubricant performance evaluation apparatus according to claim 5, wherein the pressure member includes a molding load measuring member that measures a molding load applied to the test piece. The forging lubricant performance evaluation apparatus according to claim 5 or 6, wherein a tip portion of the pressure member has a tapered portion.

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