Measurement device and method for heat transfer coefficient between resin and metal

Abstract

To allow for deriving a heat transfer coefficient between a resin and a punch by measuring the temperature of the resin 11 and the punch 21 while pressing the punch 21 against the molten resin 11 in a pot 6, and to prevent heat transfer between the pot 6 and the punch 21 and resin leakage.SOLUTION: A heat insulating material 26 for suppressing heat transfer between a pot 6 and a punch 21 and an elastic seal 27 for preventing resin leakage from between an insertion portion 21a of the punch 21 and the pot 6 are provided between an outer periphery of the insertion portion 21a to the pot 6 and an inner periphery of the pot 6 such that the elastic seal 27 sits above the heat insulating material 26.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a device and a method for measuring the heat transfer coefficient between a resin and a metal. [Background technology]

[0002] It is generally known that the heat transfer coefficient between two adjacent objects can be calculated based on the temperature distributions of both objects.

[0003] For example, Patent Document 1 describes a method for measuring the heat transfer coefficient between a motor's stator core and case. In this method, a case block made of the same material as the case is brought into contact with a core block made of the same material as the stator core and pressurized, and the core block is heated by a heater in this state. After both blocks reach a steady state with no temperature change, the temperature distributions in both blocks are measured, and the heat transfer coefficient is calculated based on the temperature distributions.

[0004] Patent Document 2 describes a method for measuring the heat transfer coefficient between a material to be hot forged and a punch. In this method, the material is heated to a predetermined temperature in an atmospheric furnace and placed in a lower die. A punch is pressed against the material, and the temperature change of the punch before and after pressing is measured. This measured temperature change is compared with the temperature change obtained by a numerical simulation in which the heat transfer coefficient is set to a predetermined value. The heat transfer coefficient is then reset and the numerical simulation is repeated until both temperature changes reach the predetermined conditions, thereby determining the heat transfer coefficient. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-200226 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-8299 Summary of the Invention [Problem to be solved by the invention]

[0006] While Patent Documents 1 and 2 determine the heat transfer coefficient between metal solids, this invention measures the heat transfer coefficient between molten resin and metal (punch) as the resin solidifies. This heat transfer coefficient determines how much heat is transferred from the resin to the mold during injection molding, for example, and makes it possible to understand the temperature distribution of the resin during molding and after demolding.

[0007] When the object to be measured is molten resin, a method similar to that used to measure the heat transfer coefficient between metal solids can be used, in which a punch is inserted into a pot containing the molten resin and pressed against the molten resin, and the temperatures of the resin and punch are measured in this state to determine the heat transfer coefficient.

[0008] However, unlike metals, resin has low thermal conductivity and large heat capacity. Therefore, as shown in Figure 7, the resin does not produce a temperature distribution with a significant gradient (temperature distribution in the punch insertion direction) only near the interface with the punch, and the temperature difference at the interface between the resin and punch is also small. Figure 7 also shows the heat transfer coefficient between the resin and mold when it is the same as the heat transfer coefficient between the Al and mold (2500 W / m 2 The temperature distribution of the punch, resin, and Al 20 seconds after a 25°C punch is pressed against the 200°C resin and Al, respectively, is shown.

[0009] Therefore, in order to obtain a reliable heat transfer coefficient when the object to be measured is a resin, it is necessary to accurately capture the temperature change of the resin and punch near the interface due to heat transfer from the resin to the punch.

[0010] The problem here is the heat transfer between the pot and the punch. That is, when the punch is inserted into the pot to measure the heat transfer coefficient, if heat transfer occurs between the pot and the punch, the temperature distribution of the punch is affected by this heat transfer, making it impossible to accurately measure the heat transfer coefficient for the heat transfer from the resin to the punch. Another problem is that, because the object to be measured is molten resin, when the punch is inserted into the pot and pressed against the molten resin, the molten resin leaks out from between the pot and the punch. In other words, it is not possible to measure the temperature while pressure is being applied to the resin.

[0011] One approach to preventing heat transfer from the pot to the punch is to increase the clearance between the pot and punch, but this increases the likelihood of resin leakage. On the other hand, reducing the clearance prevents resin leakage, but increases the likelihood of heat transfer from the pot to the punch. Installing a heat insulating material on the outer periphery of the punch that fits into the pot would prevent heat transfer from the pot to the punch, but this would slow down the solidification of the resin, leaving the problem of resin leakage from the gap between the punch or pot and the heat insulating material during temperature measurement.

[0012] In this way, preventing heat transfer from the pot to the punch and preventing resin leakage are in a contradictory relationship, in that attempting to solve one makes it difficult to solve the other.

[0013] The present invention aims to solve these contradictory problems. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention uses a combination of a heat insulating material and an elastic seal.

[0015] The heat transfer coefficient measuring device disclosed herein is a pot for storing molten resin; a metal punch that is fitted into the pot and has a tip surface pressed against the resin; a resin-side temperature sensor for measuring the temperature of the resin; a punch-side temperature sensor for measuring the temperature of the punch; a calculation device for calculating a heat transfer coefficient between the resin and the punch from the measured temperatures of the resin and the punch, respectively; a heat insulating material provided on either an outer peripheral surface of the fitting portion of the punch into the pot or an inner peripheral surface of the pot, the heat insulating material being interposed between the outer peripheral surface of the fitting portion and the inner peripheral surface of the pot when the fitting portion is fitted into the pot, thereby suppressing heat transfer between the pot and the punch; The present invention is characterized in that it is provided with an elastic seal which is provided on either the outer peripheral surface of the insertion portion of the punch or the inner peripheral surface of the pot, and which is interposed between the outer peripheral surface of the insertion portion and the inner peripheral surface of the pot above the insulating material when the insertion portion is inserted into the pot, thereby preventing leakage of the resin from between the insertion portion and the pot.

[0016] Further, the heat transfer coefficient measurement method disclosed herein includes the steps of: a step of inserting a punch into a pot storing molten resin and pressing its tip surface against the resin; measuring the temperatures of the resin and the punch; determining a heat transfer coefficient between the resin and the punch from the measured temperatures of the resin and the punch, In the step of fitting the punch into the pot, The method is characterized in that an insulating material for suppressing heat transfer between the pot and the punch and an elastic seal for preventing leakage of the resin from between the insertion portion and the pot are interposed between the outer peripheral surface of the insertion portion of the punch into the pot and the inner peripheral surface of the pot, with the elastic seal positioned above the insulating material.

[0017] With the above-described measuring device and method, heat transfer between the pot and punch is prevented by the insulating material, so that the temperature of the punch, which changes due to heat transfer between the resin and punch, can be accurately measured, and a highly reliable heat transfer coefficient can be obtained. Furthermore, even if the solidification of the molten resin is delayed by the insulating material, resin leakage from between the pot and punch due to the punch pressing against the resin can be prevented by the elastic seal.

[0018] In one embodiment of the measuring device and measuring method, the temperature of the resin is detected within a range of 10 mm from the interface between the punch and the resin. As described above, in the case of resin, a temperature distribution with a significant gradient occurs only near the interface with the punch, so the temperature of the resin is detected within a range of 10 mm from the interface in order to increase the reliability of the measured heat transfer coefficient.

[0019] In one embodiment of the measuring device, the pot is equipped with a temperature regulator that regulates the temperature of the resin contained therein. If the resin is heated externally and then transferred to the pot, heat is lost to the pot, resulting in a complex temperature distribution of the resin. In contrast, according to this embodiment, the resin can be regulated to a predetermined temperature within the pot, thereby improving the uniformity of the resin temperature before the punch is inserted into the pot, which is advantageous for obtaining a highly reliable heat transfer coefficient. The resin may be heated and melted within the pot by the temperature regulator, or it may be heated and melted externally, transferred to the pot, and then regulated within the pot by the temperature regulator.

[0020] In one embodiment of the measurement method, before the punch is inserted into the pot, the resin is heated and melted in the pot by a temperature control device to adjust the temperature to a predetermined value. This allows the resin to be adjusted to the predetermined temperature in the pot, thereby improving the uniformity of the resin temperature before the punch is inserted into the pot, which is advantageous in obtaining a highly reliable heat transfer coefficient.

[0021] The resin may be thermoplastic or thermosetting.

[0022] In one embodiment of each of the measuring device and measuring method, the punch is provided with a pressing portion that presses the elastic seal, and when the punch is pressed against the resin, the pressing portion of the punch presses the elastic seal against the upper end of the insulating material, thereby elastically deforming the elastic seal and pressing the elastic seal against the outer surface of the insertion portion of the punch and the inner surface of the pot.

[0023] This improves the sealing function of the elastic seal when the punch is pressed against the resin, thereby making it possible to reliably prevent resin leakage.

[0024] In one embodiment of the measuring device, the heat insulating material is provided so that its lower end surface faces the resin in the pot, and the elastic seal is in contact with the upper surface of the heat insulating material.

[0025] With this, when the punch is pressed against the resin in the pot, pressure is applied to the elastic seal from the pressing portion. Because the lower end surface of the insulating material is supported by the resin, the pressure from the pressing portion reliably presses the elastic seal against the insulating material. As a result, the elastic seal elastically deforms so that its inner and outer peripheries protrude toward the inner and outer peripheries, respectively, and is pressed firmly against the outer periphery of the punch's insertion portion and the inner periphery of the pot. This is advantageous for preventing resin leakage.

[0026] In one embodiment of the measuring device, a resin storage portion of the pot that stores the resin and the fitting portion of the punch have a cross-sectional shape perpendicular to the fitting direction of the punch that is a perfect circle, which makes it easy to align the punch with the pot when fitting the punch into the pot.

[0027] In one embodiment of the measuring device in which the cross-sectional shapes of the resin storage portion of the pot and the insertion portion of the punch are perfectly circular, the insulating material and the elastic seal are annular and are fitted onto the outer peripheral surface of the insertion portion of the punch.

[0028] In one embodiment of the measuring device and the measuring method, a clearance that allows air to pass but not molten resin is provided between the inserting portion of the punch or the inner peripheral surface of the pot and the insulating material, and between the inserting portion of the punch or the inner peripheral surface of the pot and the elastic seal. Therefore, when the punch is inserted into the pot, air can be released from inside the pot from the pot or between the punch and the molten resin while preventing resin leakage. [Effects of the Invention]

[0029] According to the present invention, the temperatures of the resin and punch can be measured while preventing heat transfer and resin leakage between the pot and punch, so that a highly reliable heat transfer coefficient can be obtained. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] 3A and 3B are cross-sectional views showing a part of the device before and after the punch is pressed against the molten resin. [Figure 4] FIG. 3 is a cross-sectional view showing the arrangement of a resin-side temperature sensor of the device. [Figure 5] FIG. [Figure 6] FIG. 10 is a graph showing changes in punch temperature over time when the punch is pressed against resin in the embodiment and the comparative example. [Figure 7] FIG. 10 is a graph showing the temperature distribution of the punch, resin, and Al after a predetermined time has elapsed since the punch was pressed against the resin and Al, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the scope of the present invention, its applications, or uses.

[0032] <Heat transfer coefficient measuring device> The heat transfer coefficient measuring device 1 shown in Fig. 1 is a device for measuring the heat transfer coefficient between a thermoplastic resin and a metal. This heat transfer coefficient measuring device 1 comprises a pot device 2 for storing molten resin, a punch device 3, and a calculation device 4.

[0033] The potting device 2 comprises a base 5, a pot 6 supported on the base 5, and a lid 7 that closes the upper opening of the pot 6. As shown in FIG. 2, the pot 6 is composed of a metal base 8 and a metal cylinder 9 fixed to the base 8 with its axis perpendicular. The base 8 and the cylinder 9 form a resin reservoir 12 that stores resin 11. The horizontal cross section of the resin reservoir 12 (the cross section perpendicular to the punch insertion direction, described below) is a perfect circle. The resin reservoir 12 is provided with a resin-side temperature sensor 13 that measures the temperature of the resin 11 to measure the heat transfer coefficient. The resin-side temperature sensor 13 will be described in detail later.

[0034] The potting device 2 is equipped with a temperature adjusting device that heats and melts the resin 11 contained in the resin storage section 12 and adjusts the temperature to a predetermined value. The temperature adjusting device is equipped with a plurality of rod-shaped heaters 15 embedded in the base 8, a temperature sensor (thermocouple) 16 that measures the temperature of the base 8, and a control device (not shown) that controls the operation of the rod-shaped heaters 15 so that the temperature measured by the temperature sensor 16 becomes a predetermined value. The temperature adjusting device further includes a band heater 17 wrapped around the cylindrical body 9, a temperature sensor (thermocouple) 18 that measures the temperature of the cylindrical body 9, and a control device (not shown) that controls the operation of the band heater 17 so that the temperature measured by the temperature sensor 18 becomes a predetermined value.

[0035] A lid 7 that closes the upper end opening of the pot 6 is connected to a nitrogen supply pipe 19 that supplies nitrogen to the surface of the resin 11 stored in the pot 6 to prevent oxidation of the resin 11.

[0036] The punch device 3 comprises a metal cylindrical punch 21 to be fitted into the pot 6, a punch-side temperature sensor 22 consisting of a plurality of (in this embodiment, three rod-shaped) temperature measuring probes 23 embedded in the punch 21, a heat insulating material 26, and an elastic seal 27. A rod attachment hole (screw hole) 28 to which a pressure rod of a pressure testing machine is connected is opened in the top surface of the punch 21.

[0037] <About the punch side temperature sensor 22> Each of the multiple temperature measuring probes 23 is a thermocouple, and extends forward in the punch insertion direction, i.e., downward, from the upper end of the punch 21. The multiple temperature measuring probes 23 have the temperature measuring points 23a at their tips shifted in the axial direction of the punch 21 so as to measure the temperature of each point on the punch 21 that is separated by different distances from the contact interface (hereinafter simply referred to as the "interface") between the resin 11 and the punch 21. As can be seen from Figure 1, the temperature measuring points 23a at the tips of the multiple temperature measuring probes 23 are arranged at intervals on the same circumference centered on the axis of the punch 21.

[0038] In this embodiment, the temperature measurement points 23a of the three temperature probes 23 are disposed at positions 2 mm, 4 mm, and 6 mm away from the tip surface of the punch 21.

[0039] <Insulation between punch and pot and prevention of resin leakage> The fitting portion 21a of the punch 21 that fits into the pot 6 has a perfectly circular cross section perpendicular to the fitting direction. The fitting portion 21a is concentric with the base (upper portion) 21b of the punch 21 and has a smaller diameter than the base 21b. A circular heat insulating material 26 and an elastic seal 27 are fitted into the fitting portion 21a, with the latter positioned on top and in contact with each other from top to bottom. The upper surface of the elastic seal 27 abuts against the lower surface of a portion of the base 21b that protrudes from the upper end of the fitting portion 21a. This lower surface serves as a pressing portion 29, which will be described later.

[0040] 3, the heat insulating material 26 is a cylindrical body, and is provided so as to be interposed between the outer peripheral surface of the fitting portion 21a and the inner peripheral surface of the pot 6 (the inner peripheral surface of the cylinder 9) when the fitting portion 21a is fitted into the pot 6. The heat insulating material 26 suppresses the transfer of heat between the pot 6 and the punch 21 while the punch 21 is fitting into the pot 6 and when the punch 21 is pressed against the resin 11 of the pot 6.

[0041] Elastic seal 27 is a so-called O-ring, and is provided so as to be interposed between the outer peripheral surface of fitting portion 21a and the inner peripheral surface of pot 6 above heat insulating material 26 when fitting portion 21a is fitted into pot 6. When punch 21 is pressed against resin 11 in pot 6, elastic seal 27 prevents resin 11 from leaking between pot 6 and fitting portion 21a of punch 21.

[0042] The prevention of resin leakage will now be explained. A clearance is provided between the outer peripheral surfaces of the heat insulating material 26 and the elastic seal 27 fitted into the fitting portion 21a of the punch 21 and the inner peripheral surface of the pot 6, allowing gas (nitrogen gas) inside the pot 6 to escape to the outside when the fitting portion 21a is fitted into the pot 6. In other words, the outer peripheral surfaces of the heat insulating material 26 and the elastic seal 27 fitted into the fitting portion 21a and the inner peripheral surface of the pot 6 are not in tight contact with each other without any gaps all around, but rather, with the aim of smooth fitting, a slight clearance is provided at least somewhere between the outer peripheral surface and the inner peripheral surface during fitting.

[0043] As a result, when the tip surface of the punch 21 comes into contact with the resin 11 in the pot 6 as shown in FIG. 3(A) and is pressed against the resin 11 as shown in FIG. 3(B), pressure is applied from the pressing portion 29 of the punch 21 to the elastic seal 27. Because the insulating material 26 is supported by the resin 11 and is substantially immobile, the pressure from the pressing portion 29 presses the elastic seal 27 against the upper end surface of the insulating material 26. As a result, the inner and outer peripheral portions of the elastic seal 27 elastically deform so as to protrude toward the inner and outer peripheral sides, respectively. In short, the elastic seal 27 is crushed and pressed firmly against the outer peripheral surface of the fitting portion 21a of the punch 21 and the inner peripheral surface of the pot 6. This prevents the resin 11 from leaking between the outer peripheral surface of the fitting portion 21a of the punch 21 and the inner peripheral surface of the pot 6.

[0044] <About the resin side temperature sensor 13> 4, the resin-side temperature sensor 13 has a plurality of (three in this embodiment) temperature probes 31. The plurality of temperature probes 31 are arranged horizontally at small intervals in the punch fitting direction (vertical direction) and are held by a single block 34. The block 34 is supported by a support member 35 on the pot 6 so that the upper surface of the block 34 is positioned near the upper surface of the molten resin 11 stored in the pot 6, preferably so that the upper surface of the block 34 is not immersed in the molten resin 11 and so that the upper surface of the molten resin 11 and the upper surface of the block are flush with each other.

[0045] 5, each of the temperature probes 31 is a thermocouple in which the tips of two types of metal wires 31a, 31b are joined together to form a hot junction (temperature measurement point) 31c. The metal wires 31a, 31b have portions embedded in the resin other than the hot junction 31c that are insulated and coated with a highly heat-resistant resin whose melting point is higher than that of the resin.

[0046] The multiple temperature probes 31 are grouped together with the portions of the metal wires 31a, 31b near the hot contacts 31c spaced apart vertically with small gaps between them, and are held in a block 34 made of electrical insulation. That is, the portions of the multiple temperature probes 31 near the hot contacts 31c are grouped together with small gaps between them vertically, and the electrical insulation is solidified to encase these portions into the rectangular block 34. Heat-resistant cement is preferably used as the electrical insulation material. The top surface of the block 34 is smooth. The block 34 is supported on the pot 6 by a support member 35 so that its smooth top surface is horizontal.

[0047] The metal wires 31a, 31b of each of the plurality of temperature probes 31 are joined at their protruding ends to form thermal contacts 31c so that the portions protruding from the block 34 toward the center of the resin reservoir 12 of the pot 6 form a V-shape in plan view. The thermal contacts 31c of each of the plurality of temperature probes 31 are lined up at the center of the resin reservoir 12 with small intervals in the punch insertion direction.

[0048] In this embodiment, the hot contacts (temperature measurement points) 31c of the three temperature probes 31 are located at positions 0.5 mm, 1.5 mm, and 2.5 mm away from the top surface of the block .

[0049] Support member 35 is made of electrically insulating, heat-resistant fiber, and is horizontally fixed to the upper corner of block 34. Pot 6 is made of a cylindrical body 9, which consists of an upper cylindrical portion 9a and a lower cylindrical portion 9b, which are joined vertically. Support member 35 is fixed to pot 6 with both sides sandwiched between upper cylindrical portion 9a and lower cylindrical portion 9b, so that it spans the center of pot 6's resin reservoir portion 12 and extends from one side of pot 6 to the other.

[0050] As the molten resin 11 cools and contracts, the position of the block 34 drops. To allow the block 34 (i.e., the temperature probe 31) to follow this resin contraction, the support member 35 is designed to break when a predetermined load is applied. For example, a fiber bundle having a thickness (tex count) of 1.7 g / 1000 m to 2500 g / 1000 m and made up of multiple fibers having a fiber diameter of 4 μm to 13 μm and a breaking strain of 5.5% or less can be suitably used as the support member 35.

[0051] <About Calculation Unit 4> The temperature of the resin 11 measured by the resin-side temperature sensor 13 and the temperature of the punch 21 measured by the punch-side temperature sensor 22 are converted into electrical signals and input as temperature data to the calculation device 4. The calculation device 4 calculates the heat transfer coefficient h by processing this temperature data.

[0052] Specifically, the temperature distribution in the punch insertion direction near the interface of the resin 11 is determined by fitting from temperature data at multiple points at different distances from the interface measured by the resin-side temperature sensor 13. The temperature distribution of the punch 21 in the punch insertion direction is determined by fitting from temperature data at multiple points at different distances from the interface measured by the punch-side temperature sensor 22. From the temperature distributions of the resin 11 and the punch 21, the temperature Tr on the resin 11 side and the temperature Tm on the punch 21 side at the interface are determined.

[0053] If the heat flux passing through the interface between the resin 11 and the punch 21 is q, the heat transfer coefficient h is given by "h = q / (Tr - Tm)". The calculation device 4 calculates the heat transfer coefficient h based on the temperature Tr on the resin 11 side, the temperature Tm on the punch 21 side, and the heat flux q.

[0054] The heat flux q is given by q = a × (Tm - Te) / L, where Te is the temperature at a position a length L away from the surface of the punch 21 in the punch insertion direction, and a is the thermal conductivity of the punch 21. Therefore, the heat flux q is calculated from Tm obtained by the above fitting, the above Te, the thermal conductivity a, and the length L. Note that the heat flux q that has been measured in advance and stored electronically may be used to calculate the heat transfer coefficient h.

[0055] <Method for measuring heat transfer coefficient> A method for measuring the heat transfer coefficient between resin and metal using the heat transfer coefficient measuring device 1 will be described.

[0056] <Preparation process> A punch device 3 is attached to the pressure rod of the pressure tester, and a pot device 2 is placed below the punch 21. The resin 11 to be measured is placed in the resin reservoir 12 of the pot 6, and the top opening of the pot 6 is sealed with a lid 7. Nitrogen gas is supplied into the pot 6 through a nitrogen supply pipe 19. In this state, the resin 11 is heated and melted to a predetermined temperature (e.g., 200°C) using a rod-shaped heater 15 embedded in the base 8 and a hand heater 17 wrapped around the cylinder 9. The amount of resin 11 is adjusted so that the top surface of the block 34 of the resin-side temperature sensor 13 is positioned near the top surface of the resin 11 when the resin 11 is heated and melted to the predetermined temperature. Preferably, the top surface of the block 34 is not immersed in the molten resin 11, and the top surface of the resin 11 is flush with the top surface of the block 34.

[0057] <The process of inserting and pressing a punch into the molten resin in the pot> Heating of resin 11 by heaters 15 and 17 is stopped (or may be stopped while heating), and lid 7 is removed from pot 6. The pressure tester is operated, punch 21 is inserted into pot 6, and the tip surface of punch 21 is pressed against molten resin 11. As punch 21 is inserted into pot 6, gas (nitrogen gas) inside pot 6 escapes to the outside through clearances between the inner peripheral surface of pot 6 and the outer peripheral surfaces of heat insulating material 26 and elastic seal 27 inserted into insertion portion 21a of punch 21.

[0058] When the tip surface of punch 21 comes into contact with and is pressed against molten resin 11 in pot 6 as shown in Fig. 3(A), punch 21 is slightly pressed into molten resin 11 while insulating material 26 is supported by molten resin 11 and does not move, as shown in Fig. 3(B). This applies pressure to elastic seal 27 from pressing portion 29 of punch 21, and elastic seal 27 is pressed against the upper end surface of insulating material 26. As a result, elastic seal 27 is elastically deformed and crushed, and its inner and outer peripheral sides are pressed strongly against the outer peripheral surface of insertion portion 21a of punch 21 and the inner peripheral surface of pot 6.

[0059] Therefore, the heat insulating material 26 prevents heat transfer from the pot 6 to the punch 21, and the elastic seal 27 reliably prevents the molten resin 11 from leaking between the outer surface of the insertion portion 21a of the punch 21 and the inner surface of the pot 6.

[0060] Furthermore, even if the punch 21 comes into contact with the block 34 when pressed against the upper surface of the molten resin 11, the pressure from the punch 21 is not directly transmitted to the temperature probe 31, so that the intervals between the temperature measurement points 31c of the multiple temperature probes 31 are prevented from changing.

[0061] Even if the upper surface of block 34 protrudes slightly above the upper surface of molten resin 11, when punch 21 hits block 34, support member 35 bends, causing block 34 to be pushed down along with punch 21 until its upper surface becomes flush with the upper surface of molten resin 11. Therefore, the spacing between temperature measurement points 31c of multiple temperature probes 31 does not change, and since the upper surface of block 34 becomes flush with the upper surface of molten resin 11, the distance from the interface of each temperature measurement point 31c becomes the desired distance.

[0062] <Process for measuring the temperature of the resin and punch> Once the punch 21 is pressed against the resin 11, the position of the punch 21 is fixed, and the temperatures of the resin 11 and the punch 21 are measured by the resin-side temperature sensor 13 and the punch-side temperature sensor 22. Because the resin-side temperature sensor 13 is equipped with multiple temperature probes 31, the resin temperature at multiple points at different distances from the interface is measured by the resin-side temperature sensor 13. Because the punch-side temperature sensor 22 is equipped with multiple temperature probes 23, the punch temperature at multiple points at different distances from the interface is measured by the punch-side temperature sensor 22.

[0063] When resin 11 cools and contracts, support member 35 breaks, causing block 34 to follow the contraction of resin 11, so the top surface of block 34 remains approximately flush with the top surface of resin 11. Therefore, even if a gap occurs between resin 11 and punch 21 due to the contraction of resin 11, the temperature of each position of resin 11 can be measured approximately as intended.

[0064] <Process for determining the heat transfer coefficient from the measured temperature> The heat transfer coefficient between the resin 11 and the punch 21 is calculated by the calculation device 4 from the temperatures of the resin 11 and the punch 21 at multiple points measured by the resin-side temperature sensor 13 and the punch-side temperature sensor 22 .

[0065] Specifically, the temperature distribution in the punch insertion direction near the interface of the resin 11 is determined by fitting from temperature data on the resin side at multiple points at different distances from the interface. The temperature distribution of the punch 21 in the punch insertion direction is determined by fitting from temperature data on the punch side at multiple points at different distances from the interface. From the temperature distributions of the resin 11 and punch 21, the temperature Tr on the resin 11 side and the temperature Tm on the punch 21 side at the interface are determined. The heat transfer coefficient h=q / (Tr-Tm) is calculated based on the temperature difference (Tr-Tm) at the interface and the heat flux q obtained from the temperature distribution of the punch 21.

[0066] The resin 11 cools and solidifies from a molten state as heat is absorbed by the punch 21 pressed against its upper surface. That is, a phase change from liquid to solid occurs. In this embodiment, measurement of the temperatures of the resin 11 and the punch 21 begins when the punch 21 is pressed against the resin 11, and the change in the heat transfer coefficient when the resin 11 changes from the liquid phase to the solid phase is determined from the change over time in the temperature difference (Tr - Tm) at the interface.

[0067] When a gap is generated between the resin 11 and the punch 21 due to shrinkage of the resin 11, the heat transfer coefficient of the heat transfer from the resin 11 to the punch 21 across the gap (air layer) is measured.

[0068] <Effect of combining insulation and elastic seal> The change over time in the punch-side temperature measured by the temperature probe 23 of the punch-side temperature sensor 22 when the punch 21 was pressed against the resin 11 was investigated for the above embodiment and a comparative example (without heat insulating material) in which an O-ring groove was provided at the upper end of the insertion portion 21 of the punch 21 and the elastic seal (O-ring) 27 was fitted into this groove. The results are shown in Fig. 6.

[0069] The temperature measured by the temperature probe 23 in the embodiment (combination of heat insulating material and elastic seal) is lower than that in the comparative example (no heat insulating material), indicating that the heat insulating material 26 effectively suppresses heat transfer from the pot 6 to the punch 21. Furthermore, in the comparative example (no heat insulating material), the temperature difference between the measurement point 2 mm from the interface and the measurement points 4 mm and 6 mm from the interface is large. This is believed to be due to resin infiltration into the gap between the pot 6 and the punch 21, resulting in resin leakage and uneven heat transfer from the pot 6 to the punch 21. In contrast, the temperature difference between the measurement points in the embodiment (combination of heat insulating material and elastic seal) is small. This indicates that the heat insulating material 26 and elastic seal prevent resin infiltration and resin leakage between the pot 6 and the punch 21, thereby preventing uneven heat transfer from the pot 6 to the punch 21.

[0070] <Effect of the resin-side temperature sensor> For the above embodiment and a comparative example (without support member) in which three temperature measuring probes (thermocouples) 31 were held in a block 34 and arranged extending from the side in the center of the resin storage section 12 of the pot 6, the position of the temperature measuring point 31c of each temperature measuring probe 31 was investigated when the punch 21 was pressed against the molten resin 11 and the resin 11 cooled and solidified.

[0071] In both the embodiment (with support member) and the comparison (without support member), the three temperature probes 31 were held on the block 34 so that the temperature measurement points 31c were located at positions 0.5 mm, 1.5 mm, and 2.5 mm away from the top surface of the block 34. Then, with the block 34 positioned so that its top surface was flush with the top surface of the molten resin 11, the punch 21 was inserted into the pot 6 and pressed against the molten resin 11. The aim was to measure the temperatures at positions 0.5 mm, 1.5 mm, and 2.5 mm away from the interface.

[0072] In the comparative example (without a support member), temperature measurement point 31c, which aims to measure the temperature at a position 0.5 mm away from the interface, sunk to a position 3.238 mm away from the upper surface of resin 11 due to cooling and solidification of resin 11 pressed against punch 21. Temperature measurement points 31c, which aim to measure the temperature at positions 1.5 mm and 2.5 mm away from the interface, also sunk deeply, similar to temperature measurement point 31c, which aims to measure the temperature at the 0.5 mm position.

[0073] On the other hand, in the embodiment (with support member), the temperature measurement points 31c aimed at measuring the temperature at positions 0.5 mm, 1.5 mm and 2.5 mm away from the interface were 0.502 mm, 1.557 mm and 2.360 mm away from the top surface of the resin 11 after the resin 11 pressed by the punch 21 had cooled and solidified.

[0074] From these results, it became clear that in the embodiment, although the spacing between the three temperature measurement points 31c changes slightly due to the influence of the cooling and solidifying (shrinkage) of the resin 11, when the punch 21 is pressed against the resin 11, the support member 35 keeps the top surface of the block 34 approximately flush with the top surface of the resin 11, and when the resin 11 cools and shrinks, the support member 35 breaks, keeping the top surface of the block 34 approximately flush with the top surface of the resin 11, and that the resin temperature can be measured at approximately the desired position.

[0075] Although the above embodiment is a case where the resin is thermoplastic, it goes without saying that the present invention can also be applied to thermosetting resins. [Explanation of symbols]

[0076] 1. Heat transfer coefficient measurement device 2 pot device 3 Punch device 4 Arithmetic unit 6 pots 11 Resin 12 Resin storage section 13 Resin side temperature sensor 15,17 Heater that constitutes the temperature control device 16,18 Sensors that make up temperature control devices 21 Punch 21a Inset part 21b base 22 Punch side temperature sensor 26 Insulation 27 Elastic seal 29 Pressing section

Claims

1. a pot for storing molten resin; a metal punch that is fitted into the pot and has a tip surface pressed against the resin; a resin-side temperature sensor for measuring the temperature of the resin; a punch-side temperature sensor for measuring the temperature of the punch; A heat transfer coefficient measuring device including a calculation device that calculates a heat transfer coefficient between the resin and the punch from the measured temperatures of the resin and the punch, a heat insulating material provided on either an outer peripheral surface of the fitting portion of the punch into the pot or an inner peripheral surface of the pot, the heat insulating material being interposed between the outer peripheral surface of the fitting portion and the inner peripheral surface of the pot when the fitting portion is fitted into the pot, thereby suppressing heat transfer between the pot and the punch; A heat transfer coefficient measuring device characterized by comprising an elastic seal provided on either the outer peripheral surface of the insertion portion of the punch or the inner peripheral surface of the pot, which is interposed between the outer peripheral surface of the insertion portion and the inner peripheral surface of the pot above the insulation when the insertion portion is inserted into the pot, thereby preventing leakage of the resin from between the insertion portion and the pot.

2. In claim 1, The heat transfer coefficient measuring device is characterized in that the resin-side temperature sensor detects the temperature of the resin within a range of 10 mm away from the interface between the punch and the resin.

3. In claim 1 or claim 2, The heat transfer coefficient measuring device is characterized in that the pot is equipped with a temperature control device that controls the temperature of the resin contained therein.

4. In any one of claims 1 to 3, The heat transfer coefficient measuring device is characterized in that the resin is thermoplastic.

5. In any one of claims 1 to 4, The punch is provided with a pressing portion that, when its tip surface is pressed against the resin, presses the elastic seal against the upper end of the insulating material, elastically deforming the elastic seal so that it is pressed against the outer surface of the insertion portion of the punch and the inner surface of the pot.

6. In claim 5, A heat transfer coefficient measuring device characterized in that the heat insulating material is arranged so that its lower end surface faces the resin in the pot, and the elastic seal is in contact with the upper surface of the heat insulating material.

7. In any one of claims 1 to 6, A heat transfer coefficient measuring device characterized in that the resin storage portion of the pot that stores the resin and the insertion portion of the punch have a cross-sectional shape that is perfectly circular, perpendicular to the insertion direction of the punch.

8. In claim 7, The heat transfer coefficient measuring device is characterized in that the insulating material and the elastic seal are annular and fitted onto the outer peripheral surface of the fitting portion of the punch.

9. In any one of claims 1 to 8, A heat transfer coefficient measuring device characterized in that clearances that allow air to pass but not molten resin are provided between the punch insertion portion or the inner surface of the pot and the insulation material, and between the punch insertion portion or the inner surface of the pot and the elastic seal.

10. a step of inserting a punch into a pot storing molten resin and pressing its tip surface against the resin; measuring the temperatures of the resin and the punch; determining a heat transfer coefficient between the resin and the punch from the measured temperatures of the resin and the punch, In the step of fitting the punch into the pot, A heat transfer coefficient measuring method characterized by interposing an insulating material that suppresses heat transfer between the pot and the punch and an elastic seal that prevents leakage of the resin from between the insertion portion and the pot between the outer peripheral surface of the insertion portion of the punch into the pot and the inner peripheral surface of the pot, with the elastic seal positioned above the insulating material.

11. In claim 10, A heat transfer coefficient measuring method characterized by detecting the temperature of the resin within a range where the distance from the interface between the punch and the resin is 10 mm.

12. In claim 10 or 11, A method for measuring a heat transfer coefficient, characterized in that before the punch is inserted into the pot, the resin inside the pot is heated and melted by a temperature control device to adjust the temperature to a predetermined value.

13. In any one of claims 10 to 12, A heat transfer coefficient measuring method characterized in that the resin is thermoplastic.

14. In any one of claims 10 to 13, In the step of fitting the punch into the pot, A heat transfer coefficient measuring method characterized by the fact that when the punch is pressed against the resin, the elastic seal is elastically deformed by being pressed against the upper end of the insulation material by a pressing portion provided on the punch, and the elastic seal is pressed against the outer surface of the insertion portion of the punch and the inner surface of the pot.

15. In any one of claims 10 to 14, A heat transfer coefficient measuring method characterized in that clearances that allow air to pass but not molten resin to pass are provided between the punch insertion portion or the inner surface of the pot and the insulating material, and between the punch insertion portion or the inner surface of the pot and the elastic seal.

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