JP4397765B2 - Wear amount prediction method for resin sliding parts and design method for resin sliding parts using the same - Google Patents

Description

  The present invention relates to a method for predicting the amount of sliding wear of a resin sliding part and a method for designing a resin sliding part using the same. Specifically, (1) a limit PV value Pv using a standard test piece of two materials. (2) Using the above Pv, the sliding surface temperature T is estimated from the equation. (3) Using a standard specimen of two materials, the specific wear amount at various sliding surface temperatures is measured. The specific wear amount A at the sliding surface temperature T is obtained. (4) The design wear amount Y is estimated from the above A, the designed sliding distance D and the sliding surface load load P by an equation. It consists of a process.

Application of resin to mechanical parts starts with metal replacement, and engineering plastics such as polyacetal, polybutylene terephthalate, polyamide, polyphenylene sulfide, etc. are used, and are used for applications that take advantage of their respective features.
There are many types of mechanical sliding parts such as gears, bearings, cams, clutches, washers and rollers.
One of the reasons for replacing metal is that it can be used without lubrication for sliding parts, but now, with the expansion of applications and the sophistication of required performance, "oilless" under a wider range of conditions and environments The materials themselves are making progress so that

  When using resin for sliding parts, it is important to predict strength and wear in advance. With regard to strength prediction, various predictions are made based on “material mechanics”. Recently, strength prediction by CAE has advanced and is widely used in the resin processing industry. On the other hand, with respect to wear, the basic concept of “material mechanics” in strength prediction has not been established, and many trials and errors have been repeated.

In the plastic sliding wear test, the test load F (unit: N) is the two test parts, the contact area of the two test parts is S (unit: cm ² ), and the contact pressure between the surfaces (in the present invention, the surface pressure) .) P (unit: Pa, P = F / S), sliding speed V (unit: m / s), one test part on the other test part, distance D (unit: km) The amount of wear Y (unit: mm ³ ) when sliding without rolling is obtained. In this case, the product of P and V is referred to as a PV value (unit: Pa · m / s).
The specific wear amount is often used as an index for predicting the wear amount of plastic. The specific wear amount is the wear amount per unit slip distance and unit load. Therefore, the unit of specific wear is “mm ³ / (N · km)” or “m ³ / (N · m)”. The amount of wear per moving distance is obtained. (Refer nonpatent literature 1).
The amount of wear can be calculated based on the specific amount of wear required for each combination of materials, the load applied to the sliding surface of the part and the sliding distance determined at the stage of drawing the design concept. .

For example, if the material is polyacetal resin, specific wear when combining Duracon ^TM M90, which is a non-reinforced polyacetal copolymer, with the same material in “Duracon Technology Series / Duracon Design Data” P33 issued by Polyplastics Co., Ltd. The amount is listed. (Refer nonpatent literature 2).
However, since the specific wear amount in an actual part is greatly affected by the sliding linear velocity, the sliding surface load, the ambient temperature, etc., the calculated value and the actual wear amount are almost the same.

Plastic Age, “Effects of Factors such as Contact Pressure, Friction Speed, and Temperature that Control Friction and Wear (Part 2)” (September 1985, p143-p148) includes polytetrafluoroethylene (PTFE) In each case, the results of measuring wear at various temperatures, sliding line velocities and surface pressures are described. (Refer nonpatent literature 3).
However, since it takes a lot of time to measure this much data, there are a wide variety of material combinations that are expected in the market, so such a wide range of data is also available for various material combinations. It is extremely difficult to measure all of these in reality.
Even when such data is measured, the specific wear amount is often different due to the difference in heat dissipation due to the difference in the sliding surface contact form, even if the temperature / sliding linear velocity / surface pressure conditions are the same. Since the difference between the calculated wear amount and the wear amount due to actual parts is still large, it was extremely difficult to apply to the design.

  Under these circumstances, it has been necessary to repeat the trial and error of producing a product, performing a durability test and measuring the wear, and redesigning the material based on this result, reviewing the material, producing the product again, and performing a durability test. It took a lot of time and labor, and it was difficult to develop resin sliding parts in a short time.

JIS K7218 (1986) "Plastic sliding wear test method" P33 of "Duracon TM Technology Series / Duracon TM Design Data" issued by Polyplastics Co., Ltd. Plastic Age, September 1985, p143-p148

  It is an object to provide a method for predicting the amount of wear of a resin-made sliding component with high accuracy and a method for designing a resin-made sliding component so that the amount of wear after use for a predetermined time is less than or equal to a predetermined value.

  The present inventor obtains the sliding surface temperature of the resin sliding part by calculation, and corrects the conventional calculation method such as Non-Patent Document 1 and JIS K7218, thereby making it possible to use the wear amount prediction sufficiently. The inventors have found that the accuracy can be improved to the extent that the present invention has been completed.

That is, according to the first aspect of the present invention, when two parts, one or both of which are made of a thermoplastic resin, slide, the wear amount Y of the resin sliding part is obtained by the following processes (1) to (4). A method for predicting the amount of wear is provided.
(1) Using each standard test piece made of the same material as the above two parts, combining them together, the limit PV value Pv is measured under standard conditions, and the limit slip linear velocity Vc is obtained from Pv / P = Vc.
(Here, PV value is the product of P and V when sliding with sliding surface pressure P (unit: MPa) and sliding linear velocity V (unit: cm / sec). Pv is the product of P and V when the resin reaches the flow temperature, and the critical sliding linear velocity that gives Pv at the surface pressure P is called Vc.The flow temperature is the melting point for crystalline resins, and for non-crystalline resins. (The glass transition point, the standard test piece is described in JIS K7218, and the standard condition is an atmosphere at 23 ° C. and 50% RH, where Pv is the limit PV value of the standard test piece.)
(2) The sliding surface temperature T (unit: ° C) is expressed by the formula (i) from the above Vc, the part shape indicating the sliding surface area, the sliding linear velocity, the load on the sliding surface, and the usage conditions indicating the operating ambient temperature. Estimated by
T = (V / Vc) × (Tm-23) + Tr formula (i)
V: Actual sliding line speed (cm / s)
Vc: Limiting sliding linear velocity (cm / s)
Tm: Flow temperature (℃) of the material with the lower flow temperature of the two materials
Tr: Operating ambient temperature
(3) Using the same test piece as the standard test piece in (1) above, and combining them, the specific wear amount A (unit: mm ³ / (N · km)) at the sliding surface temperature T is measured.
(However, the sliding surface temperature T is obtained separately by using a semi-standard test piece provided with a notch in the standard test piece of (1) above and measuring the test piece temperature through the notch.)
(4) From the above specific wear amount A, design sliding distance D (unit: km) and sliding surface load load F (unit: N), wear amount Y (unit: mm ³ ) Estimate according to ii).
Y = A x D x F formula (ii)
In the second aspect of the present invention, the true limit PV value Pv _R obtained by the following correction formula is taken into account of the Pv of the standard test piece in consideration of the sliding perpendicular contact width of the sliding surface of the part to be designed. The wear amount prediction method according to the first aspect of the present invention used instead is provided.
Pv _R = Pv (Tm-Tr) / (t ₁ -23 + αb ² ) Formula (iii)
Pv _R : True limit PV value
Pv: Limit PV value measured using a standard specimen
Tm: Flow temperature (℃) of the material with the lower flow temperature of the two materials
Tr: Operating ambient temperature
t ₁ : Sliding end surface temperature when a specific test piece is slid under the condition equivalent to Pv α: Constant
b: Sliding surface contact width direction of sliding surface (mm)
A third aspect of the present invention provides a method for designing a resin sliding part having a shape and physical properties so as to be equal to or less than a desired wear amount by using the wear amount prediction method according to the first or second aspect of the present invention. To do.

The number of sliding linear velocity conditions, the number of surface pressure conditions, and the number of combinations of the ambient temperature conditions, that is, the number of combinations of these conditions, that is, the product of these numbers, is the basis corresponding to this extremely large number of conditions. It was impossible in practice to measure the data because it took an enormous amount of time, and appropriate wear calculation corresponding to the conditions could not be performed.
According to the present invention, it is possible to predict wear under all conditions by only having two basic data of the relationship between the limit PV value Pv-surface pressure and the specific wear amount-sliding surface temperature in standard conditions. It becomes. For this reason, it becomes possible to predict the amount of wear at the design stage of resin sliding parts, and wear occurs without actually conducting a wear test that requires a lot of time and cost using the parts. It is possible to change the design to a difficult shape, or to select an appropriate material, so that the development period can be greatly shortened and the influence on the industry is enormous.

The present invention is a method for predicting the amount of sliding wear when two parts slide, and one or both of the two parts is a thermoplastic resin.
That is, the present invention is directed to a combination of a thermoplastic resin material and a thermoplastic resin material, or a combination of a thermoplastic resin material and another material.
As thermoplastic resin materials, the main components are polyacetal resins, polyester resins such as polybutylene terephthalate, engineering plastics composed of crystalline resins such as polyarylene sulfide resins and liquid crystalline resins, and resin compositions mainly composed thereof. Is preferably used. Moreover, you may mix | blend various lubricating components of a liquid form or a solid form with these. Moreover, you may mix | blend the reinforcing material or filler which consists of various organic substances or inorganic substances, such as granular form and fibrous form, or a mixture thereof.
Other materials are not particularly limited, and may be thermosetting resin materials, metal materials, ceramic materials, or the like.

For the case where a part made of two materials, one or both of which is a thermoplastic resin, slides, the present invention predicts the amount of wear of a resin sliding part by the following processes (1) to (4). .
As a process of (1), in the surface pressure P at which the part to be designed is used by a test using a standard test piece in the same sliding form (described later) in the same material combination as the part to be designed. The critical slip linear velocity Vc (the value of the slip linear velocity V when the resin reaches the pour point) is experimentally determined.
Alternatively, the limit PV value Pv is measured in advance under various surface pressure P conditions, a graph showing the relationship of Pv-P (for example, FIG. 1) is prepared, and Pv at a specific surface pressure P is obtained, The limit slip linear velocity Vc may be obtained from Pv / P. Specifically, the surface pressure P is calculated from the sliding contact area calculated from the sliding contact surface shape (the contact area S described above) and the sliding surface load load (the test load F described above). The limit PV value Pv corresponding to the surface pressure P is calculated from the graph. A value obtained by dividing the calculated limit PV value Pv by the design surface pressure P is the limit slip linear velocity Vc to be obtained.
The example of FIG. 1 in JIS K7218, A method specifies a hollow cylindrical test piece with each other (outer diameter 25.6 mm, inner diameter 20.0 mm, length 15 mm) combines, with polyacetal copolymer unreinforced material Duracon ^TM M90S between the material It is an example.

The sliding form referred to in the process of (1) is roughly classified into the following three.
(B) Both continuous sliding forms: The test form described in the JIS K7218 / A method is a typical example, but the sliding contact surface is a surface and the entire sliding surface of each sliding part is apparent. Above, it is a form which is always in sliding contact. Specifically, a flat friction clutch or the like is applicable.
(B) Continuous-intermittent sliding form: The test form described in the JIS K7218 / B method is a typical example, but the entire sliding surface of one of the combined parts is always in sliding contact with the other part, and the other part Is a form in which the sliding portion of the entire sliding surface changes with time, and the entire sliding surface is not in sliding contact with the counterpart component. Specifically, a cam mechanism or the like is applicable.
(C) Both intermittent sliding forms: Gears are typical examples, but the sliding parts of the combined parts change with time, and all the sliding surfaces do not slide simultaneously. . In this case, V is the relative speed.

  As described above, based on the type of material to be combined / sliding form / sliding surface load load, the critical sliding linear velocity value Vc at which the resin is melted by sliding heat is calculated under standard conditions.

As the process (2), the sliding surface temperature T is calculated from the following equation (i) using the limit slip linear velocity value Vc obtained in the process (1).
T = (V / Vc) × (Tm-23) + Tr formula (i)
V: Actual sliding line speed (cm / s)
Vc: Limiting sliding linear velocity (cm / s)
Tm: Flow temperature (℃) of the material with the lower flow temperature of the two materials
Tr: Operating ambient temperature

As the process (3), the relationship between the specific wear amount A and the sliding surface temperature T is measured in advance, and a graph (for example, FIG. 2 (the used test piece is the same as FIG. 1)) is prepared. From the graph, the specific wear amount A at the sliding surface temperature T obtained in the process (2) is read.
The measuring method of the sliding surface temperature T was measured as follows according to the sliding form.
(B) In the case of the double continuous sliding configuration, as shown in Fig. 3, the hollow cylindrical test pieces specified by the JIS K7218 / A method are combined with each other, and the fixed side test piece is processed for temperature measurement. For example, a notch is provided on the sliding surface as shown in FIG. By doing so, the surface of the moving side test piece without the notch is always visible. Directly measure the sliding surface temperature by irradiating the sliding surface of the rotating side specimen with the laser beam of the radiation thermometer through the notch. The fixed-side sliding surface does not slide instantaneously once per rotation, but the notch is made with a width of about several mm, so 90% or more slides during one rotation. There is no large temperature difference compared to the case without notches. The radiation thermometer used was THI-301S manufactured by Taxco Japan. Since the sliding surface temperature was stabilized in about 15 minutes after the start of sliding, the sliding surface temperature after 30 minutes was used.
For wear measurement, use a test piece without a notch, but for temperature measurement, use a test piece with a separate notch, and make the sliding linear velocity V, surface pressure P, and operating ambient temperature the same as during wear measurement. did.
(B) In the case of continuous-intermittent mode, the sliding surface temperature T can be measured by the method shown in FIG.
(C) In the case of both intermittent sliding, the sliding surface temperature T can be measured using the gear shown in FIG.

As the process of (4), the specific wear amount A (unit: mm ³ / (N · km)) read in the process of (3), the design sliding distance D (unit: km) and the sliding surface From the applied load F (unit: N), the wear amount Y (unit: mm ³ ) is estimated by the following formula (ii).
Y = A x D x F formula (ii)

  The above is the process of the basic method for predicting the amount of wear, but for a specific combination, there are two basic data: limit PV value in standard conditions-surface pressure graph and specific wear-sliding surface dependence With this, you can predict wear at any sliding line speed, any surface pressure, and any ambient temperature.

Hereinafter, correction of the limit PV value Pv by the part shape will be described.
Even in the same material combination / sliding form, if the sliding surface contact shape is different, the limit PV value may be different. That is, the sliding contact surface shape of the part to be designed is different from the sliding surface shape of the standard test piece that measures the relationship between the limit PV value and the surface pressure, the limit PV value of the part to be designed, The limit PV value in the process of (1) is different, and the accuracy of the wear amount calculation result may be reduced.
The present inventor has found that if the sliding surface contact shape is different, the heat dissipation of the sliding heat from the sliding surface is different, in order to improve the calculation accuracy, according to the difference in the sliding surface contact shape, We found that it was effective to correct the limit PV value.
In consideration of the contact width in the direction perpendicular to the sliding direction of the sliding surface of the part to be designed (sometimes abbreviated as simply the contact width), the limit PV value Pv of the standard specimen is corrected using the following correction formula (ii) Then, Pv _R which is a true limit PV value is calculated.
Pv _R = Pv (Tm-Tr) / (t ₁ -23 + αb ² ) Formula (iii)
Pv _R : True limit PV value
Pv: Limit PV value measured using a standard specimen
Tm: Flow temperature (℃) of the material with the lower flow temperature of the two materials
Tr: Operating ambient temperature
t ₁ : Sliding end surface temperature when the specific test piece is slid under the condition corresponding to Pv The specific test piece is the sliding of each of (i) to (c) described in the process of (1) above. It is a test piece produced for a moving form, and may be a standard test piece, for example, a hollow cylindrical test piece described in the method A of JIS K7218.
α: Heat generation constant
b: Sliding surface contact width perpendicular to the sliding surface

The above α and t ₁ are obtained by experimentally obtaining the limit PV value of the standard test piece and the limit PV value of the specific test piece having a sliding perpendicular direction contact width different from that of the standard test piece, and the both results are expressed by the formula (iii) It is obtained from the simultaneous equations assigned to.
The following is an example of a combination of DURACON ^™ M90S (melting point 163 ° C.).
First, hollow cylindrical test piece with φ25.6 × φ20.0 specified by JIS K7218 / A method (the contact width in the sliding perpendicular direction is (25.6-20.0) /2=2.8 mm, and the sliding surface area is about 2 cm ² ) )), The slip linear velocity is 15 cm / s, and the limit PV value is 8 MPa · cm / s.
On the other hand, the hollow cylindrical test piece has a narrow contact width with the sliding contact surface shape of the hollow cylindrical test piece changed to φ21.6 × φ20.0 (sliding perpendicular contact width is (21.6-20.0) /2=0.8mm The sliding surface area is about 0.52 cm ² ), and the critical PV value is 12.5 MPa · cm / s at the same sliding linear velocity of 15 cm / s.
Next, the pour point T _m of the material of the specific test piece is 163 ° C. which is the melting point. In addition, Tr = 23 because of the experimental results at 23 ° C. The simultaneous equations obtained by substituting these and experimental values of each limit PV value into the formula (iii) are as follows.
8.0 = 8.0 (163-23) / (t ₁ -23 + α × 2.8 ² )
12.5 = 8.0 (163-23) / (t ₁ -23 + α × 0.8 ² )
From these, t ₁ = 108.12 and α = 7.0.
Therefore, the specific correction formula at 23 ° C between DURACON ^TM M90S is as follows.
Pv _R = Pv (Tm-Tr) / (t ₁ -23 + αb ² ) = 8 (163-23) / (108.12-23 + 7b ² ) = 1120 / (85.12 + 7b ² )
The true limit PV value Pv _R is calculated for the material having the actual sliding perpendicular contact width b using the above correction formula.

A graph showing how the true limit PV value Pv _R changes due to the difference in the contact width in the direction perpendicular to the slide when the limit PV value Pv when measured with a standard test piece in formula (iii) is 1.0. Is shown in FIG. FIG. 9 shows an example of the correction formula (iv) for obtaining the relationship between the sliding perpendicular contact width b and the true limit PV value Pv _R when using Duracon ^TM M90S. The polyacetal may be used as a representative resin. However, other suitable resins may be selected as representative resins. This is because there is no significant difference in heat dissipation and frictional heat generation.
However, when the counterpart is a metal material or when a large amount of filler with high thermal conductivity is blended, the heat dissipation is greatly different. It is preferable to create a relational expression (iv ′) of the limit PV value Pv _R.

  The above is the method for predicting the amount of wear in the present invention. For a specific combination, there are two kinds of relationships showing the relationship between the limit sliding linear velocity-surface pressure and the specific amount of wear-sliding surface temperature in standard conditions. Based on basic data, it is possible to predict the wear of various sliding surface contact shapes at any sliding linear velocity, any surface pressure, and any ambient temperature, and further correct the limit PV value corresponding to the sliding perpendicular contact width. As a result, the prediction accuracy can be improved.

(Example)
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.
A hollow cylindrical test piece (test piece A below) described in JISK 7218 / A method having an outer diameter of 25.6 mm, an inner diameter of 20.0 mm, and a length of 15 mm as shown in FIG. 6 was prepared by injection molding using a polyacetal copolymer. As the polyacetal copolymer, Duracon ^™ M90S and Duracon ^™ NW-02 manufactured by Polyplastics Co., Ltd. were used. Further, a narrow contact width type hollow cylindrical test piece (test piece B below) having an outer diameter of 21.6 mm, an inner diameter of 20.0 mm, and a length of 15 mm was similarly produced by injection molding using a polyacetal copolymer. Using these test pieces, a wear test was performed under the combinations and conditions shown in Table 1. The measurement results of the amount of wear are also shown in Table 1.
Test piece A: JIS K7218 / A hollow cylindrical test piece (outer diameter 25.6 mm, inner diameter 20.0 mm, length 15 mm, sliding surface area 201 mm ² )
Specimen B: Narrow contact width type hollow cylindrical specimen (outer diameter 21.6mm, inner diameter 20.0mm, length 15m, sliding surface area 52mm ² )

Example 1
According to the present invention, the wear amounts of test numbers 1 #, 3 #, and 4 # in Table 1 are determined in accordance with the above-described steps (1) to (4) as follows.
(1) Obtain each critical slip linear velocity Vc under standard conditions.
Both tests combined material, and it is polyacetal copolymer unreinforced material Duracon ^TM M90S each other, because the sliding form is a bicontinuous sliding form, appropriate combinations, the limit PV value of the sliding form - the surface pressure The relationship was measured and plotted as shown in FIG.
From this relationship, the critical sliding linear velocity Vc (value under standard conditions) at a predetermined surface pressure P (sliding surface load F / contact area S) is obtained as follows.
Test number 1 #: 100cm / s,
Exam number 3 #: 100cm / s Exam number 4 #: 100cm / s
(2) Obtain sliding surface temperature T from Vc.
The results of estimating the actual sliding linear velocity and the sliding surface temperature T at the operating ambient temperature from the above equation (i) using the Vc obtained above are shown below.
Sliding surface temperature (1 #) = 50/100 × (163-23) + 23 = 93 (℃)
Sliding surface temperature (3 #) = 50/100 × (163-23) + (-30) = 40 (℃)
Sliding surface temperature (4 #) = 120/100 × (163-23) + 23 = 191 (℃)
(3) The specific wear amount at the sliding surface temperature is obtained from the relationship between the sliding surface temperature and the specific wear amount.
FIG. 2 shows the result of measuring the relationship between the sliding surface temperature and the specific wear amount in advance using a standard test piece having the same sliding form as the part to be designed and calculated.
The specific wear amount (mm ³ / (N · km)) at each sliding surface temperature obtained in (2) above is shown in FIG.
Exam number 1 #: 300 × 10 ^-3
Test number 3 #: 50 × 10 ⁻³ , Test number 4 #: Melting because the sliding surface temperature exceeds the melting point.
(4) Estimate the amount of wear.
From each specific wear amount, each design sliding distance D (unit: km) and each sliding surface load load F (unit: N), each wear amount Y (unit: mm ³ ) The results estimated by ii) are shown below. In addition, when displaying the amount of wear on a weight basis, the density of the material was multiplied.
Test number 1 #: 300 × 10 ⁻³ mm ³ /(N·km)×12N×43.2 km × 1.41 mg / mm ³ = 219.3 mg
Test number 3 #: 50 × 10 ⁻³ mm ³ /(N·km)×12N×43.2 km × 1.41 mg / mm ³ = 36.5 mg
Test number 4 #: Cannot be measured because the sliding surface temperature exceeds the melting point.
The above estimation results are equal on both the rotating side and the fixed side.
Table 2 shows the wear amount calculation results and measurement results.
The calculated value and the measurement result are in good agreement, and by using the prediction method of the present invention, it was possible to predict the wear amount of the resin sliding parts with extremely high accuracy.

(Example 2)
The wear amount of test number 2 # in Table 1 was estimated in the same manner as in Example 1.
The material combination is polyacetal copolymer resin, but since it is a combination of non-reinforced grade Duracon M90S and resin sliding grade Duracon NW-02, the relationship between limit PV value and surface pressure corresponding to this combination (Fig. 7) and ratio The relationship between the amount of wear and the sliding surface temperature (FIG. 8) was used. Table 2 shows the estimation results and measurement results for wear.
The calculated value and the measurement result are in good agreement, and by using the prediction method of the present invention, it was possible to predict the wear amount of the resin sliding parts with extremely high accuracy.
When the sliding grade is used on the fixed side, the overall amount of wear is reduced compared to when using M90S.

(Example 3)
According to the present invention, the wear amounts of test numbers 5 # and 6 # using the test piece B in Table 1 were calculated.
(1) When calculating the limit slip linear velocity Vc under standard conditions, the limit PV value Pv is obtained in the same manner as in Example 1, and then the standard test piece and the sliding contact width are corrected.
Since the material combination is Duracon M90S, which is a non-reinforced polyacetal copolymer material, and the sliding form is a continuous sliding form, Vc was obtained using the relationship of FIG.
Test number 5 #: Limit sliding linear velocity Vc = 100cm / s
Test number 6 #: Limit sliding linear velocity Vc = 100cm / s
The sliding line speed of test number 5 # is 30 cm / s.
Test No. 6 # has a sliding linear velocity of 120 cm / s, which exceeds the limit sliding linear velocity of 100 cm / s, which concludes that the sliding surface melts. However, in practice, the limit PV value due to the difference in the sliding contact width must be corrected. Since it is a combination of M90S, correction is performed using FIG.
Since test numbers 5 # and 6 # are both test pieces B and the contact width in the sliding perpendicular direction is 0.8 mm, the correction factor for determining the true limit PV value Pv _R from the limit PV value Pv is 1.55 from FIG. Become. The true limit slip linear velocity Vc _R was calculated below using this correction coefficient.
Test No. 5 # True limit sliding linear velocity Vc _R = 100cm / s × 1.55 = 155cm / s
Test No. 6 # True limit sliding linear velocity Vc _R = 100cm / s × 1.55 = 155cm / s
Therefore, the sliding surface does not melt at the sliding line speed of 120 cm / s in test number 6 #.
Hereinafter, steps (2) to (4) are performed in the same manner as in Example 1, and the results are shown in Table 2.
The calculated values and the measurement results are in good agreement, and by using the prediction method of the present invention, it was possible to predict the wear amount of resin sliding parts having various widths with extremely high accuracy.

(Comparative Example 1)
Wear calculation was performed using the specific wear amount measured under the fixed method which is a conventional method.
For test numbers 1 # to 6 # in Table 3 (the same combination material and the same sliding form as test numbers 1 # to 6 # in Table 1), the specific wear amount was measured under the measurement conditions shown in Table 3. . Using this specific wear amount, the wear amount was determined by the same surface pressure and sliding distance as in Table 1 using equation (ii). The results are shown in Table 4.

The relationship between the limit PV value and the contact pressure in the case of continuous sliding using polyacetal non-reinforced materials is experimentally obtained and graphed. The relationship between the sliding surface temperature and the specific wear amount in the case of continuous sliding using polyacetal non-reinforced materials is experimentally obtained and graphed. It is a figure which shows the measuring method of the sliding surface temperature in the case of both continuous sliding forms. It is a figure which shows the measuring method of the sliding surface temperature in the case of a continuous-intermittent sliding form. It is a figure which shows the measuring method of the sliding surface temperature in the case of both intermittent sliding forms. It is a figure which shows the hollow cylindrical test piece of the JISK 7218 / A method description. The relationship between the limit PV value and the surface pressure in the case of both continuous sliding using a non-polyacetal non-reinforced material-polyacetal sliding grade was experimentally determined and graphed. The relationship between the sliding surface temperature and the specific wear amount in the case of bicontinuous sliding using a polyacetal non-reinforced material-polyacetal sliding grade was experimentally determined and graphed. Using specimens of various widths between non-reinforced polyacetal materials, the relationship between sliding surface temperature and specific wear in the case of continuous sliding was experimentally determined, and the sliding perpendicular contact width b-true limit PV value This is a graph showing the relative relationship of Pv _R.

Claims (3)

A wear amount predicting method for predicting the wear amount Y of a resin sliding part in the following processes (1) to (4) when two parts, one or both of which are made of a thermoplastic resin, slide.
(1) Using each standard test piece made of the same material as the above two parts, combining them together, the limit PV value Pv is measured under standard conditions, and the limit slip linear velocity Vc is obtained from Pv / P = Vc.
(Here, PV value is the product of P and V when sliding with sliding surface pressure P (unit: MPa) and sliding linear velocity V (unit: cm / sec). Pv is the product of P and V when the resin reaches the flow temperature, and the critical sliding linear velocity that gives Pv at the surface pressure P is called Vc.The flow temperature is the melting point for crystalline resins, and for non-crystalline resins. (The glass transition point, the standard test piece is described in JIS K7218, and the standard condition is an atmosphere at 23 ° C. and 50% RH, where Pv is the limit PV value of the standard test piece.)
(2) The sliding surface temperature T (unit: ° C) is expressed by the formula (i) from the above Vc, the part shape indicating the sliding surface area, the sliding linear velocity, the load on the sliding surface, and the usage conditions indicating the operating ambient temperature. Estimated by
T = (V / Vc) × (Tm-23) + Tr formula (i)
V: Actual sliding line speed (cm / s)
Vc: Limiting sliding linear velocity (cm / s)
Tm: Flow temperature (℃) of the material with the lower flow temperature of the two materials
Tr: Operating ambient temperature
(3) Using the same test piece as the standard test piece in (1) above, and combining them, the specific wear amount A (unit: mm ³ / (N · km)) at the sliding surface temperature T is measured.
(However, the sliding surface temperature T is obtained separately by using a semi-standard test piece provided with a notch in the standard test piece of (1) above and measuring the test piece temperature through the notch.)
(4) From the above specific wear amount A, design sliding distance D (unit: km) and sliding surface load load F (unit: N), wear amount Y (unit: mm ³ ) Estimate according to ii).
Y = A x D x F formula (ii) The true limit PV value Pv _R obtained by the following correction formula is used in place of Pv of the standard test piece in consideration of the sliding perpendicular contact width of the sliding surface of the part to be designed. The wear amount prediction method described in 1.
Pv _R = Pv (Tm-Tr) / (t ₁ -23 + αb ² ) Formula (iii)
Pv _R : True limit PV value
Pv: Limit PV value measured using a standard specimen
Tm: Flow temperature (℃) of the material with the lower flow temperature of the two materials
Tr: Operating ambient temperature
t ₁ : Sliding end surface temperature when a specific test piece is slid under the condition equivalent to Pv α: Constant
b: Sliding surface contact width direction of sliding surface (mm)   A method for designing a resin sliding part having a shape and physical properties so as to be equal to or less than a desired wear amount by using the wear amount prediction method according to claim 1.