Sensing device of pressure and temperature in mold

A sensing device of pressure and temperature in a mold comprises: a housing communicating with a mold cavity, and including a channel and an accommodating space; a base on a bottom surface of the housing, and including a mesa on a top; a strut in the accommodating space, and a front end thereof extended into the channel and exposed to the mold cavity; a strain structure between the mesa and a back end of the strut, and located on the mesa; a strain gage on the strain structure to measure a deformation amount of the strain structure the mold cavity and transforming the deformation amount into deformation amount information; a temperature-sensing element in the strut to measure a temperature of the strut, and transforming the temperature into strut temperature information; and a processing unit to obtain the deformation amount information and the strut temperature information.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Taiwan Patent Application No. 107142887, filed on Nov. 30, 2018, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Technical Field

The present invention is a sensing device of pressure and temperature in a mold, and in particular, a sensing device for real-time measurement of pressure and temperature changes of a mold in a same position in a mold cavity.

Related Art

Injection molding is a rapid molding machining method without cutting, for example, a process such as ejection molding and pressure casting, and has features such as high production efficiency, good economic indicators, high dimensional accuracy and good interchangeability. Therefore, injection molding is widely applied to and rapidly developed in large-scale industries. Pressure casting is a main molding method of light metals such as aluminum, magnesium and zinc, and is suitable for producing large complex thin-walled housing parts. Die castings have become an important component of products in fields such as automobiles, sports equipment, electronics, and aerospace, where the automotive industry is a main field of applications of pressure casting technologies, accounting for more than 70%. With rapid development of fields such as automobiles, motorcycles, internal combustion engines, electronic communications, instrumentations, household appliances, and hardware, functions and application fields of the die castings constantly expand, thereby promoting rapid development of pressure casting technologies.

However, currently, designs and production schemes of an injection molding product are both based on actual production experience, and are performed in a manner combining CAD and CAE. Therefore, a simulated in-mold pressure curve is quite different from an actual in-mold pressure curve, as shown inFIG. 1, while problems in an actual production process are mostly analyzed and measures are taken based on actual experience. Currently, an injection molding industry faces at least the following problems: 1. Assembly quality and aging conditions of process equipment are different, and process parameter correction efficiency is low; 2. Finished product quality cannot be monitored in real time, and can be only learned through post-production sampling inspection; 3. Costs of small batch production are excessively high, and inventory optimization cannot be achieved.

The American patent U.S. Pat. No. 6,345,974B1 discloses an ejector pin with pressure sensor, where an injection pin of the ejector pin includes a pin of an extruded injection workpiece and a sleeve smoothly sleeving the pin. An end of the pin faces a mold cavity by guiding an opening of parts of the end. A cavity is defined by a step part of a lower end of the sleeve. A U-shaped strain forming part located in a base part of the pin is disposed in the cavity. A strain sensor is attached on a lower surface of a crossbeam of the strain forming part. When pressure of injected resin is applied to the end of the pin, a downward load applied to the pin bends the crossbeam downwards. An installation position of only a sensing element configured in this structure is outside a mold, belonging to an indirect measurement mode, and a position in which the pin props the crossbeam needs to be a center of the crossbeam. Otherwise if the propping position is slightly off-center, a distortion rate of deformation data will be greatly increased.

SUMMARY

A purpose of the present invention is to provide a sensing device for directly measuring an in-mold pressure and an in-mold temperature in an injection molding process in a mold, and the sensing device is applied to a signal output line reserving a strain gage and a temperature-sensing element in a strain structure of a non-pressure transfer path, so that both the strain gage and the temperature-sensing element can be installed in the sensing device.

To achieve the foregoing purpose, the present invention provides a sensing device of pressure and temperature in a mold, and a structure of the sensing device includes: a housing, disposed in the mold and in communication with a mold cavity of the mold through a top surface, where the housing includes a channel disposed on the top surface and an accommodating space in communication with the channel, and a bottom surface of the housing includes an open end in communication with the accommodating space; a base, disposed in the open end of the bottom surface of the housing to close the accommodating space, and including a mesa on a top; a strut, disposed in the accommodating space, where a front end of the strut is extended into the channel and exposed to the mold cavity, so that after the front end transfers pressure of the mold cavity, the strut performs an axial displacement in the channel; a strain structure, disposed between the mesa and a back end of the strut and located on the mesa, and configured to transform the pressure transferred by the displacement of the strut into a deformation amount of the strain structure; at least one strain gage, disposed on the strain structure and configured to measure the deformation amount of the strain structure and transform the deformation amount into deformation amount information; at least one temperature-sensing element, disposed in the strut and configured to measure a real-time temperature of the strut and transform the temperature into strut temperature information; and a processing unit, electrically connected to the strain gage and the temperature-sensing element respectively to obtain the deformation amount information and the strut temperature information.

In an embodiment, the top surface of the housing is flush with a mold cavity surface, and an end surface of the front end of the strut remains flat with the top surface when the strut is not under pressure during an initial installation.

In an embodiment, the strut further includes a strut body connected to the front end and a back end platform connected to the strut body and back to the front end, the back end platform is located in the accommodating space and abutted against the strain structure, a diameter of the back end platform is greater than a diameter of the channel, and an elastic part is sleeved on the strut body, so that two ends of the elastic part are respectively connected to an end surface of the channel through the back end platform and the accommodating space to limit a moving range of the elastic part, and the elastic part is configured to revert the strut to an original position when the strut relieves an external force and performs the axial displacement.

In an embodiment, the temperature-sensing elements are disposed on the strut and the strain structure, and are respectively configured to measure the strut temperature information and a real-time temperature of the strain structure, and return the strut temperature information and the real-time temperature to the processing unit.

In an embodiment, the strain structure includes a platen section, a base plate section and a pair of support beams respectively connected to the platen section and the base plate section at two ends, the base plate section is located on the mesa, the platen section is adjacent to an back end of the strut, the pair of support beams is disposed parallel to a moving direction of the strut, and a beam body of the pair of support beams, after taking the pressure exerted by the platen section, respectively bends and deforms in a direction back to another support beam, and the at least one strain gage is disposed in a beam body of one of the pair of support beams.

In an embodiment, the support beams may be made of materials such as metal and ceramic, or even may be made of plastic in a low temperature occasion. In principle, the support beams may be made of any material with a deformation amount in the accommodating space not causing a permanent deformation.

In an embodiment, that the base plate section is located on the mesa is: a hollow locating slot is formed in a central position of the base plate section, and a bump matching the locating slot is disposed on the corresponding mesa.

In an embodiment, a blind hole is disposed in an end surface center of the back end of the strut, and through holes are disposed in a center of the strain structure and a center of the base, so that transmission lines of power and signals of the strain gages and the temperature-sensing elements may penetrate outside the housing and the base.

In an embodiment, the processing unit respectively obtains the deformation amount information of the strain structure and the strut temperature information, and further estimates an actual mold cavity pressure value after estimating an effect on the deformation amount of a material of the strain structure in the strut temperature.

In an embodiment, the processing unit respectively obtains the deformation amount information of the strain structure, a real-time temperature of the strain structure and the strut temperature information at a same time, and further estimates an actual mold cavity pressure value after converting an effect of the real-time temperature of the strain structure on the deformation amount of a material of the strain structure.

Features of the present invention are: the present invention may provide a change process curve of process pressure and temperature of the mold cavity in a process stage, to achieve a purpose of determining finished product quality and verifying equipment functions, and injection molding process parameters may be measured to develop a quality detection system, thereby providing great help for the determining of the finished injection product quality. Previously, limited by sensing structure designs, many different sensors are used in different locations to perform a mold state monitoring, so that an installation and a configuration of a system are complicated, and sensing cannot be performed from a same location. A sensor established by the present invention may be used to measure a temperature and pressure change of the mold in real time. By using the sensor provided by the present invention to measure the pressure and temperature in the mold, the verification of the current injection molding equipment functions and determining of on-line finished product quality may be integrated. The sensing device of pressure and temperature in a mold provided by the present invention may measure the pressure and temperature of the mold in real time, to resolve system complication and low mold integration of an existing mold sensing technology.

DETAILED DESCRIPTION

The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The accompanying drawings are mainly simplified schematic diagrams and a basic structure of the present invention is merely schematically described. Therefore, merely elements related to the present invention are marked in the drawings, and the shown elements are not drawn in numbers, shapes, scales and the like during implementation. Dimensions of the elements during actual implementation are actually an optional design, and layouts and forms of the elements may be more complicated.

Referring toFIG. 2toFIG. 7, a sensing device1of pressure and temperature of this embodiment is applied to a mold A, and the sensing device1of pressure and temperature includes: a housing11, a base12, a strut13, a strain structure14, a strain gage15and a temperature-sensing element16. The housing11is disposed in the mold A and exposes a top surface111of the housing11to a mold cavity B of the mold A, the housing11includes a channel112hollowly disposed in the top surface111and an accommodating space113also disposed in the housing11and in communication with the channel112, and a bottom surface114of the housing11includes an open end1141in communication with the accommodating space113. The base12is disposed in the open end1141of the bottom surface114of the housing11. Specifically, as the embodiments shown inFIG. 3,FIG. 6andFIG. 7, a section of male threads123may be disposed on a peripheral wall of the base12, and a section of female threads1142may be correspondingly disposed on an inner wall of the open end1141of the housing11. The male threads123and the female threads1142are screwed to each other, so that the base12is separately disposed on the bottom surface114of the housing11(certainly, if there is no need to disassemble the base12, manners such as welding and bonding may be used to combine the base12with the open end1141of the bottom surface114of the housing11), to close the accommodating space113. A mesa121is disposed on a top of the base12, and a through hole122is disposed in a center of the base12through a central shaft of the base12. The strut13is disposed in the accommodating space, and a front end131of the strut13is extended into the channel112and exposed to a space of the mold cavity B. As shown inFIG. 7, when the mold cavity B generates pressure F, the front end131of the strut13transfers the pressure of the mold cavity B, so that the strut13performs an axial displacement in the channel112to a direction of the accommodating space113. The strain structure14is disposed between the mesa121and a back end132of the strut13and located on the mesa121, and is configured to transform the pressure transferred by the displacement of the strut13into a deformation amount of the strain structure14. The strain gage15is disposed on the strain structure and configured to transform the deformation amount of the strain structure14into deformation amount information151. Certainly, if there is a plurality of deformation members (for example, support beams143shown inFIG. 6) of the strain structure14, the strain gage15may be disposed on the deformation members one by one, or on a chosen one. The temperature-sensing element16(that is, a strut temperature-sensing element16a) is disposed in the strut13(for example, as shown inFIG. 3andFIG. 6, a blind hole1322may be hollowly disposed in an end surface center of the back end132of the strut13) and configured to measure a real-time temperature of the strut13and transform the temperature into strut temperature information16a1(because the front end131of the strut13is exposed to the mold cavity B, the strut temperature information16a1may obtain a more accurate actual temperature value of the mold cavity B). The processing unit17is electrically connected to the strain gage15and the temperature-sensing element16respectively to obtain the deformation amount information151and the strut temperature information16a1as a basis for transforming the deformation amount information151into pressure information.

In an embodiment, as shown inFIG. 6, the top surface111of the housing11is flush with a mold cavity surface B1, and an end surface of the front end131of the strut13remains flat with the top surface111when the strut13is not under the pressure F of the mold cavity B in an initial installation state. As shown inFIG. 7, when an injection molding process and the like is performed, the mold cavity B performs a pressure increase change because of injection molding of liquid C, the pressure F of the mold cavity B pushes the strut13to a top (a platen section141) of the strain structure14. Because the strain structure14is located on the fixed mesa121of the based12by a bottom (a base plate section142), the base plate section142of the strain structure14is fixed, so that pressure from the platen section141causes the support beam143to deform, and the strain gage15disposed on the support beam143may measure a deformation value.

In an embodiment, as shown inFIG. 3, the strut further comprises a strut body133connected to the front end131and a back end platform1321connected to the strut body133and located in the back end132, the back end platform1321is located in the accommodating space113and abutted against the strain structure14, a diameter of the back end platform1321is greater than a diameter of the channel112, and an elastic part18(for example, a compression spring or a taper washer) is sleeved on the strut body133, so that moving ranges of two ends of the elastic part18are respectively limited by a top surface of the back end platform1321and an end surface of the channel112in communication with the accommodating space113, and the elastic part18is configured to, after the strut13relieving an external force (the mold cavity pressure), and when the strain structure14reverts and pushes the strut13back, make the platen section141of the strain structure14abutted against the back end132(that is, a bottom surface of the back end platform1321) of the strut13.

In an embodiment, the temperature-sensing element16may be the strut temperature-sensing element16aand a strain structure temperature-sensing element16b, where the strut temperature-sensing element16ais disposed on the strut13, the strain structure temperature-sensing element16bis disposed on the strain structure14, and the strut temperature-sensing element16aand the strain structure temperature-sensing element16bmay respectively measure the strut temperature information16a1and strain structure temperature information16a2of the strain structure14, and return the strut temperature information16a1and the strain structure temperature information16a2to the processing unit17.

In an embodiment, as shown inFIG. 6andFIG. 7, the strain structure14includes the platen section141, the base plate section142and a pair of elastic support beams143respectively connected to the platen section and the base plate section at two ends, the base plate section142is located on the mesa121(specifically, a locating manner of the base plate section142is to form a hollow locating slot1421in a central position of the base plate section142, and dispose a bump1211matching the locating slot1421on the corresponding mesa121), the platen section141is adjacent to the back end132of the strut13, the pair of support beams143is disposed parallel to an axial moving direction of the strut13(as shown inFIG. 3), and a beam body1431of the pair of support beams143, after taking the pressure F exerted by the platen section141, respectively bends and deforms in a direction back to or facing another support beam143(that is, bending outwards or inwards the strain structure14, for example,FIG. 4andFIG. 5shows implementation forms of the pair of support beams143bending outwards the strain structure14), and the strain gage15may be disposed in one of the pair of support beams143or the beam body1431of the two support beams143. As shown inFIG. 3, thicknesses of the two support beams143may be the same, or may be different, and the two support beams143may be disposed in a same diameter or in different diameters compared to a central shaft X of the strain structure14and is based on a location or a quantity of the strain gage15disposed in one of or both the two support beams143.

Certainly, the support beams143are preferably made of metal materials, but are not limited hereto, for example, may be made of materials such as ceramic, or even may be made of plastic in a low temperature occasion, and the support beams131may be made of any material so long as the support beams143may resist a temperature of a mold process in the accommodating space113, and a deformation amount of the support beams143does not cause a permanent deformation.

It should be noted, a through hole1411is disposed in a center of the platen section141of the strain structure14, a through hole1422is disposed in a center of the base plate section142and a through hole122is disposed in a center of the base, so that transmission lines (L1, L2) of power and signals of the strain gages15and the temperature-sensing elements16may penetrate outside the housing11and the base12, as shown inFIG. 6andFIG. 7. Certainly, after the transmission lines (L1, L2) are pulled out through the through hole122, sealing may be performed as needed.

Further, the processing unit17respectively obtains the deformation amount information151of the strain structure14by the strain gage15and the strut temperature information16a1by the strut temperature-sensing element16a, and further estimates an actual mold cavity pressure value after estimating an effect of the strut temperature information16a1on the deformation amount of the material of the strain structure14(the deformation amount of a same material may vary under different temperatures). Further, in addition to disposing the strut temperature-sensing element16ain the strut13, when the strain structure temperature-sensing element16bis also disposed in the strain structure14, the processing unit17may respectively obtain the deformation amount information151of the strain structure14, real-time temperature strain structure temperature information16b1of the strain structure14and the strut temperature information16a1at a same time, and further estimates the actual mold cavity pressure value after converting an effect of the real-time temperature of the strain structure14on the deformation amount of the strain structure14. In this embodiment, because the real-time temperature of the strain structure14may be obtained directly, a more accurate deformation amount effect may be obtained, and the actual mold cavity pressure value may be more correctly estimated, so as to provide a change process curve of process pressure and temperature of the mold cavity in a process stage, to achieve a purpose of determining finished product quality and verifying equipment functions.

The foregoing embodiments are merely exemplary descriptions of principles, characteristics and effects of the present invention, and are not intended to limit the scope of the present invention. Any person skilled in the art can make some modifications or variations to the foregoing embodiments without departing from the spirit and the scope of the present invention. Any equivalent change or modification made based on the disclosed content of the present invention shall fall within the scope of the following claims. Therefore, the scope of protection of present invention shall be subject to the following claims.