JP5971822B2 - Molding machine and temperature control method for molding machine - Google Patents

Description

The present invention relates to a molding machine capable of selectively performing molding only by the first molding member, or molding performed by attaching a second molding member that is detachable to the first molding member, and the temperature of the molding machine. It relates to a control method.

Although it is not a literature that can be selectively implemented by molding only by the first molding member and molding by attaching a second molding member that is detachable to the first molding member, As a molding machine that performs molding by attaching a second detachable molding member, those described in Patent Document 1 and Patent Document 2 are known. Patent Document 1 relates to a molding die for an injection molding machine, and by making a marker part formed separately from a molding die as a nesting element, it is possible to replace the marker part even when wear or the like occurs. It can be exchanged only, and it is described that productivity is high. Although there is no direct description regarding temperature control in Patent Document 1, a molding die of a general injection molding machine is to control the temperature by detecting the temperature of temperature-controlled water sent to the mold on the temperature control device side. Is used to control the temperature of the mold.

Patent Document 2 relates to a press molding machine and its mold, and describes that an optical product is press-molded by attaching a stamper to at least one of heated molds. Although there is no direct description in Patent Document 2, in general, a large number of stampers are prepared and exchangeable according to optical products. In addition, Patent Document 2 has no description of selectively performing both molding with a stamper and molding without mounting in a single press device, but a mechanism for simultaneously abutting a resin plate, which is an invention matter, on both sides of a press. It describes the use for molding without a stamper attached. Furthermore, Patent Document 2 describes that the temperature of the mold can be adjusted by circulating warm water, oil, steam, etc., whose temperature is adjusted in the upper and lower mold fluid passages, and that the heating means may be a heater, or the stamper is heated. Attaching means is also described.

Patent Document 3 relates to a press molding apparatus for a carbon fiber composite molded product using a multistage press. In the case of Patent Document 3, a primary molded product molded by a multistage press is sent to a press apparatus in another secondary molding process to perform secondary molding. In the case of this device, a dedicated press device is required, which is suitable for mass production but not suitable for multi-product small-volume production. In FIG. 4 of Patent Document 3, it is shown that a primary molded product having irregularities is formed instead of a flat plate, but a detachable molding member is not used.

JP 55-128344 A (Claim 1, page 2, lower left column, FIG. 1) JP2013-62845A (0017, 0018, 0048, FIG. 1) JP 2014-76548 A (Claim 6, 0051, FIG. 1, FIG. 2, FIG. 4)

In Patent Document 1 and Patent Document 2, molding is performed by attaching a second molding member that is detachable to the first molding member, but molding of only the first molding member is also selectively performed. Since it is not possible, there are few molding variations. In Patent Document 1 and Patent Document 2, when a member corresponding to the second molded member is attached and molded, the temperature sensor is not provided in the member corresponding to the second molded member. The temperature could not be detected near the point, and accurate temperature control could not be performed. For this reason, there has been a problem that a molded product molded by the molding machine has a defect or the quality is not stable.

In the present invention, in view of the above-described problems, molding using only the first molding member and molding performed by attaching a second molding member that is detachable to the first molding member can be selectively performed. Molding machine and molding machine temperature control capable of ensuring molding variations with one molding machine and more accurately controlling the temperature of the second molding member when molding with the second molding member attached It aims to provide a method.

The molding machine according to claim 1 of the present invention can selectively perform molding using only the first molding member and molding performed by attaching a second molding member that is detachable to the first molding member. A first molding member having a molding surface, a heating means or a cooling means capable of heating the first molding member, and a first molding member, a heating means or a cooling means. A first temperature sensor capable of detecting at least one temperature, a second molding member that is detachably attached to the first molding member and has a molding surface, and a temperature of the second molding member can be detected When molding is performed using only the second temperature sensor and the first molding member, the temperature control of the heating means or the cooling means is performed using the first temperature sensor, and the first molding member is subjected to the second control. When the molding member is attached and molding is performed, at least the second temperature sensor is used. Wherein the temperature control mechanism to implement the temperature control of the heating means or cooling means provided by using the value of the service.

The molding machine according to claim 2 of the present invention is characterized in that, in claim 1, the second molding member is not provided with heating means or cooling means.

According to a third aspect of the present invention, there is provided a molding machine temperature control method in which molding is performed with temperature control only by the first molding member and a second molding member that is detachable from the first molding member is attached. A molding machine temperature control method capable of selectively performing molding, a first molding member having a molding surface, a heating unit capable of heating the first molding member, or a cooling unit capable of cooling, A first temperature sensor capable of detecting the temperature of at least one of the first molding member, the heating means or the cooling means, and a second molding member which is detachably attached to the first molding member and has a molding surface And a second temperature sensor capable of detecting the temperature of the second molding member, and when performing molding using only the first molding member, the heating means or the cooling means using the first temperature sensor The second molding is performed on the first molded member. Which comprises carrying out the temperature control of the heating means or cooling means using the value of the temperature sensor of at least the second mold member when performing molding attached to wood.

The temperature control method for a molding machine according to claim 4 of the present invention is the temperature control of the heating means or the cooling means according to claim 3, using the detection values of both the first temperature sensor and the second temperature sensor. It is characterized by implementing.

The molding machine of the present invention is a molding machine capable of selectively performing molding using only the first molding member and molding performed by attaching a second molding member that is detachable to the first molding member. , Detecting a temperature of at least one of the first molding member having the molding surface, the heating means capable of heating the first molding member or the cooling means capable of cooling, and the first molding member, the heating means or the cooling means. A first temperature sensor that can be attached, a second molding member that is detachably attached to the first molding member and has a molding surface, and a second temperature sensor that can detect the temperature of the second molding member When molding with only the first molding member, the first temperature sensor is used to control the temperature of the heating means or cooling means, and the second molding member is attached to the first molding member. When molding, use at least the value of the second temperature sensor A temperature control mechanism for controlling the temperature of the heating means or the cooling means is provided, so that various types of molding can be performed with one molding machine, and accurate temperature control can be performed at that time. . The temperature control method for the molding machine of the present invention has substantially the same effect.

It is a schematic explanatory drawing of the 1st Embodiment of this invention. It is a schematic explanatory drawing of the 2nd Embodiment of this invention.

First, a press molding machine 11 according to a first embodiment of the present invention will be briefly described with reference to FIG. Although the whole illustration is omitted, the press molding machine 11 is a multistage press as shown in FIG. However, in FIG. 1, only the upper and lower two hot plates 12 which are the first molding members are shown, and the other illustrations are omitted. The hot plate 12 is provided with a heater 13 which is a heating means for directly heating the hot plate 12. In the first embodiment, a cartridge heater is used as the heater 13, but the type and control method of the heater 13 are not limited. In addition to the heater 13, the heating unit may be a heating unit that performs heating with a heat medium such as steam or oil, a heating unit that uses induction heating, or a heating unit that uses the heater 13 together. The press device 11 is provided with a mold clamping cylinder (not shown) which is a pressurizing unit and a heating unit and above or below the hot plate 12. The molding part including the hot plate 12 of the press device 11 may be accommodated in a vacuum chamber.

The hot plate 12 is a plate of steel or cast iron having a predetermined thickness, and has a flat molding surface 12a on its surface. The hot plate 12 is directly provided with a first temperature sensor 14 (thermocouple) so that the temperature of the hot plate 12 can be detected. The first temperature sensor 14 is connected to the temperature control device 15. The number and type of the first temperature sensors 14 are not limited, and the first temperature sensor may be a non-contact type and not directly attached to the hot plate 12. When the heating means for heating the heating plate 12 is a heating medium such as steam or oil, in addition to the first temperature sensor 14 of the heating plate 12, a passage for supplying or discharging the heating medium to the heating plate or a heating medium It is assumed that the first temperature sensor 14 is also provided in the supply device. Further, when the heating means is the heating medium, it is also assumed that the first temperature sensor 14 on the first molding member side is provided only in the heating means such as a passage for supplying or discharging the heating medium or a heating medium supply device. . Therefore, the 1st temperature sensor 13 should just be provided in at least one of the hot platen 12 or a heating means (or cooling means).

The temperature control device 15 includes an input unit 16 to which a signal of the first temperature sensor 14 is input, an arithmetic processing unit 17 that performs temperature control using the signal, a storage unit 18 that stores the temperature data and set values, Functional units such as a setting input unit 19 that performs setting and an output unit 20 that outputs a command signal to the heater 13 are provided. An SSR 21 that controls energization of the heater 13 is provided between the output unit 20 and the heater 13. In FIG. 1, only the connection relationship between the lower heat plate 12 and the temperature control device 15 is described, but the upper heat plate 12 and each heat plate have the same structure.

Next, the molding die 22 as the second molding member attached to the molding surface 12a on the upper surface of the hot plate and the molding surface 12a on the lower surface of the hot plate will be described. The mold 22 is detachably attached to the hot plate 12. The lower mold 23 attached to the lower heat plate 12 of the forming mold 22 has a convex molding surface 23a on the upper surface side at the time of attachment, and a contact surface 23b to the heat plate 12 on the lower surface side. I have. The upper mold 24 attached to the upper hot plate 12 of the molding die 22 has a concave molding surface 24a on the lower surface side at the time of mounting, and has an abutment surface 24b for the hot plate 12 on the upper surface side. Yes. A forming die 22 composed of a pair of a lower die 23 and an upper die 24 is made of a metal such as steel, cast iron or stainless steel. However, in the case where a member having a good pressurizing force and good thermal conductivity is used, brass or aluminum may be used for a part or all of it. Depending on the shape of the molded product, the molding die 22 may have only one of the lower die 23 and the upper die 24.

Further, the lower mold 23 will be described as an example of the molding die 22. A second temperature sensor 25 (thermocouple) is installed in the vicinity of the molding surface 23a inside the lower mold 23, and the temperature of the lower mold 23 is detected. It is possible. The second temperature sensor 25 is connected to the input unit 16 of the temperature control device 15. Since the upper mold 24 has the same structure, description and illustration are omitted. The second temperature sensor 25 may be provided on either the lower mold 23 or the upper mold 24. In addition, the second temperature sensor 25 may be attached to the mold 22 by attaching the second temperature sensor 25 to the surface of the molding surface. Further, when the mold 22 is a thin plate such as a stamper, the second temperature sensor 25 may be attached to the back surface of the mold 22. Further, in the above, the second temperature sensor 25 is connected to the temperature measuring unit, and if the temperature measuring unit is provided inside or on the surface of the mold 22, the other part of the temperature sensor is inside the hot plate 12. Or it may be external. The number and type of the second temperature sensor 25 are not limited, and the second temperature sensor may be a non-contact type and not directly attached to the mold 22.

In the first embodiment, the molding die 22 as the second molding member does not include heating means such as a heater. Therefore, the structure of the mold 22 is simplified, and the manufacturing cost and the mold weight can be reduced. Further, it is possible to reduce the trouble of connecting the heating means to the temperature control device or the medium supply device when the molding die 22 is used. Furthermore, since no heating means is provided, the maintenance of the mold 22 is facilitated.

In the present invention, the thickness of the second molded member not provided with a heating means such as a heater is not limited. However, if the thickness is too thin, the first temperature sensor 14 of the first molded member can control the molding surface. This is often possible, and the meaning of providing the second temperature sensor on the second molded member is reduced. When the thickness of the second molded member is too thick, the heating from the heating means of the first molded member does not reach the molding surface of the second molded member satisfactorily. Therefore, the present invention is most effective when the thickness of the thickest part from the contact surface 22b of the second molded member to the molding surface 22a (molding surface 22a substantially parallel to the contact surface 22b) is 5 to 5 as an example. 150 mm, more preferably 10 to 100 mm.

The temperature control mechanism of the press molding machine 11 is constituted by heating means such as a heater 13 for heating the hot plate 12, the first temperature sensor 14, the second temperature sensor 25 of the mold 22, the temperature controller 15 and the like. The The present invention can also be applied to a cold press in which a medium such as cooling water is passed through the flow path of the hot plate 12. In that case, the temperature control mechanism of the press molding machine 11 is constituted by the cooling means for cooling the hot plate 12, the first temperature sensor 14, the second temperature sensor 25 of the mold 22, the temperature control device 15, and the like.

Next, the temperature control method at the time of shaping | molding of the press molding machine 11 of this invention is demonstrated. In the present invention, when forming a flat plate-like final molded product from a flat plate material such as a prepreg or a wiring board, only the hot plate 12 as the first forming member is used, and between the heated hot plates 12 and 12. Perform press molding with temperature control. However, when forming an uneven molded product from a flat plate or an already uneven material or a molten material, the forming die 22 corresponding to the hot plate 12 is attached. As described above, the temperature control mechanism of the present invention enables the single press molding machine 11 to selectively perform the molding using only the hot plate 12 and the molding using the molding die 22 without using the molding die 22. The variation of the molded product to be molded can be expanded.

When molding is performed using the molding die 22, the method of attaching the molding die 22 to the hot plate 12 is not limited, and it may be attached by an electromagnet or the like in addition to attachment by a bolt (not shown). Further, nothing may be provided between the hot plate 12 and the mold 22, but a cushion material or a metal plate having a thermal conductivity of a certain level or more may be inserted. Then, the signal line of the second temperature sensor 25 of the mold 22 is connected to the temperature control device 15.

Next, energization of the heater 13 of the hot plate 12 is started via the SSR 21 in response to a command from the temperature control device 15 of the temperature control mechanism, and the temperature rise control of the hot plate 12 and the mold 22 is controlled by closed loop control (PID control). Start. At that time, both the temperature signal detected from the first temperature sensor 14 of the hot plate 12 and the temperature signal detected from the second temperature sensor 25 of the mold 22 are taken into the temperature control device 15 from the input unit 16. It is. In the arithmetic processing unit 17 of the temperature control device 15, the signals are combined at an arbitrary ratio set in advance, and a feedback value used for the glowed loop control of the heater 13 is calculated. And the said feedback value is compared with the setting value set beforehand, and the command signal for control of the heater 13 is output from the output part 20 to SSR21 according to excess and deficiency.

The combination of the temperatures of the hot plate 12 and the mold 22 as described above is mainly used for the following reason. By measuring only the temperature of the hot plate 12 with the first temperature sensor 14 and performing feedback control, the hot plate 12 is directly heated and approaches the set temperature, and the molding die 22 not provided with heating means such as a heater is indirectly heated. It approaches the set temperature. However, the temperature of the mold 22 may differ from the set temperature due to heat dissipation or disturbance. The present invention has the effect of reducing this difference. Further, when the control is performed using only the second temperature sensor 25 of the mold 22 without using the first temperature sensor 14 of the hot plate 12, the heater 13 of the hot plate 12 and the second temperature sensor 25 are separated. However, since the response is delayed because it is indirectly heated, overshoot or hunting may occur. The present invention has the effect of preventing this and enabling accurate temperature control by detecting both the temperature of the hot plate 12 and the temperature of the mold 22 and reflecting them in feedback control.

The coefficients for obtaining the feedback value from the temperature of the hot plate 12 and the temperature of the mold 22 are the heater capacity, the heat capacity and thermal conductivity of the hot plate and the mold, the shape and thickness of the mold, and the molding material before molding. Since it is influenced by various conditions such as temperature, molding temperature, volume of molded product, etc., it is determined in consideration of them. Therefore, the coefficient at the time of calculating | requiring the said feedback value may differ with respect to the shaping | molding die 22 and molded product which are replaced | exchanged.

When the feedback value based on the detected values of the first temperature sensor 14 of the hot plate 12 and the second temperature sensor 25 of the mold 22 reaches the molding start temperature, the molding material is applied to the molding surface 23a of the lower mold 23 of the mold 22. M is placed and a mold clamping cylinder (not shown) is operated to start press molding. Although the press molding time varies depending on the molded product, during pressurization, temperature control by closed-loop control (PID control) is performed by comparing the feedback value summed up with an arbitrary coefficient and the preset temperature set value as during pressurization. Is done. As for pressurization control, closed loop control (PID control) such as multistage control is performed. When a predetermined pressurizing time elapses, the mold clamping cylinder is operated to open the mold, and then the molded product is taken out.

Next, a second embodiment will be described. In the second embodiment, the molding die 32 of the injection molding machine 31 corresponds to the first molding member, and the cores 42A and 42B correspond to the second molding member. Although not shown, the injection molding machine 31 includes an injection device and a mold clamping device, and a fixed mold 34 is attached to a fixed plate 33 of the mold clamping device. A movable mold 36 is attached to the movable plate 35. In the vicinity of the cavity surface inside the fixed mold 34 and the movable mold 36, temperature control channels 37 and 38 are formed, respectively. The flow paths 37 and 38 are connected to a temperature control device 39 incorporating a heater and the like through a hose. The medium sent from the temperature control device 39 to the flow paths 37 and 38 is generally temperature-controlled cooling water. In this case, the flow path 37 including the hose and the temperature control device 39 are cooling for cooling the mold 22. Configure the means. When the heating medium and the cooling medium are sent to the flow path 37, the flow path 37 including the hose and the temperature adjustment device 39 constitute a heating means for heating the molding die and a cooling means for cooling. Further, in the case of a molding die for thermosetting resin, a heating means for heating the molding die such as a heater is provided.

The movable mold 36, which is the first molding member, includes a first temperature sensor 40 (thermocouple) that can detect the temperature of the movable mold. The first temperature sensor 40 is connected to the temperature control device 41. The type and number of the first temperature sensors 40 are not limited and may be provided outside the fixed mold 34 and the molding mold 32.

A core 42A is detachably attached to the cavity surface 36a of the movable mold 36. In the present embodiment, the core 42A is not provided with heating means or cooling means, and a second temperature sensor 43 (thermocouple) is attached. The second temperature sensor 43 is connected to the temperature control device 41. The second temperature sensor 43 is connected to the temperature measuring unit, and if the temperature measuring unit is provided inside or on the surface of the core 42A, the other part of the temperature sensor is the mold of the movable mold 36. It may be inside. In the second embodiment, the temperature of the cooling means including the temperature control device 39 including the flow paths 37 and 38 of the molding die 32, the first temperature sensor 40 for detecting the temperature of the molding die 32, the core 42A, and the like are adjusted. The temperature control mechanism of the injection molding machine 31 is constituted by the second temperature sensor 43 to be detected, the temperature control device 41 and the like.

In the molding die 32 of the second embodiment, the case where injection molding is performed by forming a cavity with only the fixed die 34 and the movable die 36 without attaching the core 42A, and the core 42A provided with a cavity surface The case where injection molding is performed by forming a cavity by attaching a core and the case where injection molding is performed by forming a cavity by attaching a core 42B having another cavity surface instead of the core 42A is selectively performed. Can be implemented. Therefore, it is possible to mold three types of molded products with one molding die 32. In addition, when exchanging several removable cores, the number is not limited. Further, the core may cover only a part of the cavity surface of the movable mold 36. Further, the core may be provided in the fixed mold 34 or in both the fixed mold 34 and the movable mold 36.

The temperature control device 41 of the temperature control mechanism includes an input unit 44 to which signals from the first temperature sensor 40 and the second temperature sensor 43 are input, an arithmetic processing unit 45 that performs temperature control using the signals, and the temperature data. And a storage unit 46 for storing set values, a setting input unit 47 for setting temperature, and an output unit 48 for outputting a command signal to the temperature control device 39. The temperature control device 41 may be incorporated in the temperature control device 39 or may be incorporated in the main body of the injection molding machine 31.

Next, a temperature control method using the temperature control mechanism of the injection molding machine 31 according to the second embodiment of the present invention will be described. In the second embodiment, when the thick plate is formed, the cavity is formed using only the movable mold 36 and the fixed mold 34 which are the first molding members, and injection molding is performed. At this time, at least the first temperature sensor 40 of the movable mold 36 detects the mold temperature, the temperature control device 39 controls the temperature of the temperature-controlled water, and the mold is directly cooled so that the mold temperature becomes the set temperature. . At this time, since the core 42A is not provided with a cooling means, it is indirectly cooled from the movable mold 36 side. The first temperature sensor 40 does not detect the temperature of the members inside the mold, but may measure the temperature of the temperature control medium such as the cooling water in the temperature control device 39 or the flow path 38.

Next, when forming a thin plate, the core 42A is attached to the cavity surface 36a of the movable mold 36, and injection molding is performed. At this time, both the temperature signal detected from the first temperature sensor 40 of the movable mold 36 and the temperature signal detected from the temperature sensor 43 of the core 42 </ b> A are taken into the temperature control device 41 from the input unit 44. . In the arithmetic processing unit 45 of the temperature control device 41, the feedback value is calculated by synthesizing the signals with an arbitrary ratio coefficient set in advance. Then, the feedback value is compared with a set value set in advance, and a command signal for temperature control of the temperature control medium is output from the output unit 48 to the temperature control device 39 in response to excess or deficiency. The same control is performed when the core 42B is replaced with another cavity surface.

The feedback value at this time is calculated by calculating the heat capacity of the portion of the molding die 32 provided with the flow path 38 and the like, the heat capacity of the cores 42A and 42B, the thickness, the thermal conductivity, and the surface shape. Since it is influenced by various conditions such as capacity, heating cylinder temperature, type of molding material, volume of molded product, etc., it is determined in consideration of them. Therefore, the coefficient may not be constant.

When the molten resin cools in the cavity to which the core 42A is attached, the movable mold 36 is opened, the molded product is ejected by an ejector device (not shown), and taken out of the molding die 32 by an unillustrated take-out device. .

Note that the temperature control method using the temperature control mechanism of the first embodiment and the second embodiment described above includes the first molding member (hot plate 12 or molding die 32) and the second molding member (molding), respectively. The value of the temperature sensor (14 and 25 or 40 and 43) of the mold 22 or the core 42A) is added to obtain a feedback value. However, in both the first embodiment and the second embodiment, the temperature of the first molding member (hot plate 12 or molding die 32) is determined only by the temperature sensor 43 of the second molding member (molding die 22 or core 42A). A temperature control method for controlling the heating means or the cooling means (the heater 13 or the temperature device 39) may be used.

Furthermore, in both the first embodiment and the second embodiment, the temperature control mechanism includes a second molding member (molding die 22 or core 42A) with heating means or cooling means (such as a heater or a temperature control channel). It may be provided and can directly heat or cool the second molded member. In that case, at the time of molding performed by attaching the second molding member, the first temperature sensor of the first molding member and the feedback value obtained by adding the detection values of the second temperature sensor of the second molding member are used. The heating means or the cooling means of both the forming member and the second forming member are controlled.

Furthermore, the molding die 22 as the second molding member of the first embodiment may be carried together with the molding material in a form for placing the molding material or sandwiching the molding material. In this case, the temperature detection of the mold 22 is not limited to this, but it is preferable to detect the temperature using a non-contact temperature sensor.

The present invention is not enumerated one by one, but is not limited to that of the above-described embodiment, and it goes without saying that those skilled in the art also apply modifications made in accordance with the spirit of the present invention. is there. The molding machine targeted by the present invention includes a die-cast molding machine that performs metal molding, a hollow molding machine, and a stamping molding machine that supplies molten resin to a lower mold and presses it.

11 Press molding machine 12 Hot plate (first molding member)
13 Heaters 14 and 25 Temperature sensor 15 Temperature control device 22 Mold (second molding member)

Claims (4)

A molding machine capable of selectively performing molding only by the first molding member and molding performed by attaching a second molding member that is detachable to the first molding member,
A first molded member having a molding surface;
Heating means capable of heating the first molded member or cooling means capable of cooling;
A first temperature sensor capable of detecting the temperature of at least one of the first molded member, heating means or cooling means;
A second molded member that is detachably attached to the first molded member and has a molded surface;
A second temperature sensor capable of detecting the temperature of the second molded member;
When molding is performed using only the first molded member, the temperature of the heating unit or the cooling unit is controlled using the first temperature sensor, and the second molded member is attached to the first molded member. A molding machine comprising a temperature control mechanism for performing temperature control of the heating means or the cooling means using at least the value of the second temperature sensor when performing. The molding machine according to claim 1, wherein the second molding member is not provided with heating means or cooling means. This is a temperature control method for a molding machine in which molding involving temperature control only by the first molding member and molding performed by attaching a second molding member detachable to the first molding member can be selectively performed. And
A first molded member having a molding surface;
Heating means capable of heating the first molded member or cooling means capable of cooling;
A first temperature sensor capable of detecting the temperature of at least one of the first molded member, heating means or cooling means;
A second molded member that is detachably attached to the first molded member and has a molded surface;
A second temperature sensor capable of detecting the temperature of the second molded member,
When performing molding only with the first molding member, the first temperature sensor is used to control the temperature of the heating means or cooling means,
When performing molding with the second molding member attached to the first molding member, temperature control of the heating means or cooling means is performed using at least the value of the temperature sensor of the second molding member. Temperature control method for molding machine. 4. The temperature control method for a molding machine according to claim 3, wherein the temperature control of the heating means or the cooling means is performed using detected values of both the first temperature sensor and the second temperature sensor.