JPH01127141A - Mold drying furnace - Google Patents

Abstract

PURPOSE:To increase an energy efficiency and to quickly dry by providing an antenna for projecting a microwave closely opposed to one face among the opening faces of metal made outer box for flask molding which in itself is taken as a cavity. CONSTITUTION:A microwave is led into slot antenna 32c, 34c via rectangular waveguides 32a, 34a from a microwave generator. The microwave is directly projected like a plane wave toward the pattern molding after a core 12 from both sides for the opposed opening faces 16, 17 of a metal made outer box 20 for flask molding. A direct inner part heating for the core 12 contg. a moisture is caused, the quick drying of the core 12 is achieved and an uniform wide ranged heating is acted on the core 12 having a complicated contour curved face.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates in particular to a mold drying furnace for dry-smoking molds such as sand mold cores in the field of casting technology.

This invention relates to a mold drying furnace using microwave heating, which utilizes as a cavity the metal outer box itself for containing a mold for manufacturing a mold.

[Prior Art] Conventionally, as shown in FIG. 3, a mold drying oven using microwave heating of this type includes an oven l having an entrance door la and an exit door 1b that can be opened and closed in the vertical direction, , a roller conveyor 2 that transports the rollers 2a on which the metal outer box 10 containing the IX type is placed, and a microwave generator that transmits microwaves from the top of the oven l to the inside thereof. a waveguide 3 to be introduced into
and an infrared thermometer 5 attached to the top of the thermometer.

Metal outer box 1 for framing placed on roller conveyor z
0 is a split mold 11a as a silicone rubber resin mold,
It has a built-in prototype for forming the sand mold core 12 using aluminum upper frames 13a, 13b,
Aluminum lower frames 14a, 14b, aluminum front frame (not shown), and aluminum back frame (
(not shown), and the prototype is held between four front, top, and bottom frame plates, and the remaining opposing left and right sides are opened to expose the split molds 11a and llb. During curing, the metal outer box lO for framing containing the prototype is placed in the oven 1 with the entrance door 1a opened, and the sand mold core 12 is dry-molded by microwave heating.
After that, the exit door tb is opened and the product is taken out.

[Problems to be Solved] However, the above conventional mold drying furnace using microwave heating has the following problems.

■In dry molding of the core 12, it is necessary to place the entire metal outer box 10 containing mold a into the mold drying furnace, and the inner volume of the furnace is large, as well as the metal outer box for framing. The core 10 is made up of aluminum acid frame plates on four sides, front and bottom, and the core 12 itself is mostly shielded from microwaves by the aluminum acid frame plates, but the microwaves are only transmitted from the left and right sides opened by multiple reflections of the microwaves. Since the microwave is irradiated onto the child 12, the microwave loss is significant, the energy efficiency is low, and the drying speed is relatively slow.

■The roller 2a is necessary for the convenience of taking in and out the metal outer box 10 for framing that contains the prototype, but since the roller conveyor 2 is located at the bottom of the oven 1, it is exposed to microwave irradiation, so it is resistant to Special roller 2a for microwave
This increases the manufacturing cost of the mold drying oven.

■It is necessary to constantly detect the dry state by aligning the infrared thermometer 5 directly above the gas vent hole 15 of the metal outer box for framing lO, but since the internal volume of the furnace is large, the gas vent hole 15
Since the distance between the thermometer and the infrared thermometer 5 is long, it is very difficult to match the positions of the two.

[Object of the Invention] The present invention is intended to solve the above-mentioned problems, and its purpose is to achieve high energy efficiency and quick drying by compactly configuring the internal volume of the furnace, and to reduce wrinkles due to temperature control. An object of the present invention is to provide a mold drying oven in which the positioning of an infrared thermometer with respect to a mold is easy, and in addition, the manufacturing cost is low.

[Means for solving the problem] In order to achieve the above object, a mold drying oven according to the present invention has the following features:
It has the following two characteristic structural requirements.

■There must be a metal outer box with at least one side open for housing the prototype for molding the core, etc.

■The metal outer box for framing itself is used as a cavity, and there is a microwave irradiation antenna that should be airtightly opposed to at least one of its open surfaces.

The "microwave irradiation antenna" includes, for example, a case where the flange has a choke for preventing microwave leakage on the inner surface of the flange.

[Function] According to the mold drying furnace configured as described above, during n-type curing, the microwave irradiation antenna is used in close opposition to the open surface of the metal outer box for framing,
The metal outer box itself for framing is y1 yen! ! Since it is used as a cavity for drying, the microwaves emitted from the microwave irradiation antenna are irradiated directly from the open surface toward the model, coupled with multiple reflections inside the metal outer box for framing. The temperature of the mold containing moisture inside the prototype rises due to internal heating, and the internal volume of the furnace (volume inside the metal outer box for framing) is a fraction of that of conventional molds.

The heating efficiency is high, the drying speed of the mold becomes faster, and mold drying with less microwave loss is realized.

[Example] Next, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of a mold drying furnace according to the present invention, and FIG. 2 is a plan view of the same embodiment.

In the figure, 20 indicates split molds 11a and l for molding the core 12.
This is a metal outer box for framing, which contains a prototype of silicone rubber, etc. of lb., and is made of aluminum upper frames 13a and 13b.
, aluminum lower frames 14a, 14b, aluminum front frame (not shown), and aluminum rear frame (
(not shown), the prototype is sandwiched and housed by frame plates on four sides, front and back, top and bottom, and the remaining two left and right opposing sides te and t7 are open. Aluminum upper frame 13
a, 13b and aluminum lower frame 14a, 1
A flange f is provided at the side end of the aluminum upper frame 13a, 13b, and a split gas vent pipe 18 is protruded from the parting line PL of the aluminum upper frame 13a, 13b. Furthermore, a general roller truck 19 is removably mounted below the aluminum lower frames 14a and 14b.

30 is a circular microwave irradiation device, which has an inner width W that is slightly wider than the width W of the metal outer box 20 for framing, and has a right microwave irradiation section 32 and a left microwave opposite thereto. It consists of a wave irradiation section 34 and an upper arch 38 that has an infrared thermometer 38a and connects both the microwave irradiation sections 32 and 34. The right microwave irradiation section 32 includes a rectangular waveguide 32a that introduces microwaves from a microwave generator (not shown) such as a magnetron, and a large number of slots) 3.
2b... In the slot antenna 32c having a U-shaped cross section, the inner surface of the flange F, which should be closely opposed to the flange f of the metal outer box 20 for framing, is provided with a microwave leakage prevention material. chalk 32
d is formed. Similarly, the left microwave irradiation section 34
consists of a rectangular waveguide 34a that introduces microwaves from a microwave generator (not shown) such as a magnetron, and a slot antenna 34c having a large number of slots 34b, and has a U-shaped cross section. At 34c, a choke 34d for preventing microwave leakage is formed on the inner surface of the flange F which should be closely opposed to the flange f of the metal outer box 20 for framing. Note that, instead of the slot antennas 32c and 34c, a horn antenna, a surface wave transmission antenna, or the like may be used as the microwave irradiation antenna.

Next, the effects of the above embodiment will be explained. First, in the mold manufacturing process, the split molds 111L and llb for core removal are
Foundry sand is injected and filled into the master mold through the gas vent pipe 18, and the sand mold core 12 is molded.In order to cure the sand mold core 12, the metal outer box 20 for framing is used as it is in a circular shape. It is inserted between both the microwave irradiation parts 32 and 34 of the microwave irradiation device 30.

Here, the metal outer box 20 for framing is inserted in such a way that its open surface 18.17 faces both microwave irradiators 32,34. Since the inner width W of the microwave irradiation device fi30 is only slightly wider than the width W of the metal outer box 20 for framing, to the extent that it can be inserted and removed freely, both microwave irradiation units 32, 34 and the frame An airtight space is defined inside of the metal outer box 20 with a minute gap G between them. In addition, inserting the metal outer box 20 for framing,
Since this is carried out using the roller cart 18, the work efficiency is good. After insertion, the infrared thermometer 38a is set so as to be located directly above the gas venting pipe 18.

Next, from the microwave generator (not shown) to the rectangular waveguide 3
Microwaves are introduced into the slot antennas 32c and 34c via the slot antennas 2a and 34a, and the metal outer box 2 for framing is inserted.
Microwaves are directly irradiated from both sides of the opposing open surfaces 18 and 17 of the core 12 in the form of a plane wave toward the exposed master mold from which the core 12 is to be molded. slot antenna 32c,
The flange F of the slot antenna 34c and the flange f of the metal outer box 20 for framing are closely opposed to each other with a minute gap G, and the slot antennas 32c, 34c and the metal outer box 20 for framing have a micrometer inside. Since a closed space is defined as the wave irradiation space, the metal outer box 20 itself has substantial significance as a cavity for drying the core 12, and the radiated microwaves are emitted from the open surface. 18. 17 uniformly irradiates the mold directly as a substantially plane wave, causing direct internal heating to the moist core 12, thereby achieving rapid drying of the core 12 and making it suitable for framing. Aluminum upper frame 13a of metal outer box 20, 1
3b, the aluminum lower frames 14a and 14b, the aluminum front frame (not shown), and the aluminum rear frame (not shown). The microwave irradiation from the core 12, which has a complex contoured surface, uniformly heats and dries the core 12 over a wide range synergistically. Compared to conventional furnaces, the internal volume of the furnace (substantially the volume inside the metal outer box 20 for framing) is a few times smaller, so the heating efficiency is greatly improved.
The drying speed of the core 12 is faster than before.

In the above embodiment, the microwave irradiation units 32 and 34 are arranged symmetrically opposite to each other with respect to the core 12 for each of the split molds 11a and llb. It is possible to improve the drying speed and achieve uniform drying, but it goes without saying that even with a single microwave irradiation section, rapid drying can be achieved by making the furnace volume more compact. In such a case, the metal outer box 20 for framing is arranged close to and facing the single microwave irradiation unit so that it can move forward and backward, and a metal plate, etc. is placed on the remaining open surface of the metal outer box 2tl for framing. A cavity of substantially small volume can be defined by shielding with.

In the above embodiment, a circular microwave irradiation device stirrup 3 is installed.
Nakako against 0! 2 is inserted and set between the microwave irradiation parts 32 and 34 to form the minimum necessary cavity, and then the core is manufactured. This method applies direct microwave heating with high heating efficiency to the core 12, but since the irradiated microwave is directly irradiated to the core 12 in the form of a plane wave from a nearby part, it was conventionally used to cause multiple reflections. There is no need for a starter, etc., and the number of parts can be significantly reduced, and from this point of view, it is possible to reduce the manufacturing cost of the mold drying oven. Also, the minute dimensions of the minute gap G.

In particular, microwave leakage is prevented as much as possible by AIRing microwave leakage prevention chips on the inner surfaces of the flanges F of the slot antennas 32c and 34c, and the outside of the metal outer box 20 for framing is protected against microwaves. Therefore, the roller cart 19 for carrying in and out the metal outer box 20 for framing is not a special one with a microwave-resistant design.
Since a general trolley is sufficient, the manufacturing cost of the mold drying furnace itself can be reduced from this point of view as well.

The gas vent pipe 1B also functions as a molding sand inlet and a microwave leakage prevention mechanism, but since the space between the metal outer box 20 for framing and the upper arch 3B is not the furnace space, vq
The infrared thermometer 36a can be easily aimed at the opening of the gas vent pipe 18, and the adjustment for monitoring the temperature rise of the core 12 is easier than before. It is convenient. In addition, since the distance between the core 12 and the infrared thermometer 38, which is the object to be measured, is short and the area between them is a non-microwave irradiation area, it is possible to suppress fluctuations in the temperature measurement value, thereby reducing instrument errors. It can be effectively removed, the temperature increase state of the core 12, that is, the dry state can be accurately monitored, and this contributes to improving the quality of curing.

[Effects of the Invention] As explained above, the mold drying furnace according to the present invention uses the metal outer box for framing itself, which is open on at least one side and is used as a cavity, to house a master mold for forming a mold such as a core. Since it has a microwave irradiation antenna which should be airtightly opposed to at least one of the open surfaces, the following effects can be achieved.

■Since the metal outer box for framing itself is essentially a drying oven, the inner volume of the oven is significantly smaller than in the past, and the micro- Because wave heating is the main method, energy efficiency is high;
A short drying time of the mold is achieved. Furthermore, the mold drying furnace can be made more compact.

1. Since the outside of the small furnace, that is, the outside of the metal outer box for framing, is a non-microwave irradiation area, no special microwave-resistant measures are required.
It is possible to externally attach accessories such as a trolley, and furthermore, since there is no need for components such as a starter for the purpose of multiple reflection of microwaves, it is possible to provide a mold drying oven with substantially lower manufacturing costs. .

■In addition, because the internal volume of the furnace is small and the outside of the metal outer box for framing is a non-microwave irradiation area, the distance between the thermometer placed outside and the mold to be dried is reduced compared to conventional methods. This makes it possible to achieve optimal drying by making it easier to aim the thermometer and improve temperature measurement accuracy, thereby improving curing quality.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a mold drying furnace according to the present invention. FIG. 2 is a plan view of the same embodiment. FIG. 3 is a longitudinal sectional view showing an example of a conventional mold drying furnace. [Explanation of main symbols] 11a, llb...Resin split mold as a prototype, 1
2... Foundry sand core as a mold, 13a, 13
b... Aluminum upper frame, 14a, 14b...
・Aluminum lower frame, 16...Open left side, 17
...Open right side, 18...Gas vent pipe, PL...
・Parting line, 18...Roller truck, 20・
・・Metal outer box for framing for mold production, 30...
Gate-shaped microwave irradiation device, 32... Right microwave irradiation part, 32a, 34a... Rectangular waveguide, 32b. 34b...Slot, 32c, 34c...Slot antenna, 32d, 34d...Choke for preventing microwave leakage, 34...Left microwave irradiation part, F
, f...Flange, 38a...Infrared thermometer, G.
...Minute gap.

Claims (2)

[Claims] (1) A metal outer box for framing that is open on at least one side in which to house a prototype for molding a mold such as a core, and at least one of the open sides with the metal outer box for framing itself serving as a cavity. A mold drying oven characterized by having a microwave irradiation antenna which should be airtightly opposed to one side of the mold drying oven. (2) The mold drying oven according to claim 1, wherein the microwave irradiation antenna has a choke for preventing microwave leakage on the inner surface of its flange.