JPH07100380B2 - Method for manufacturing platen for impact printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an impact printer platen, and more particularly to a method for manufacturing an impact printer platen suitable for high strength and light weight against a printing impact force. Regarding

[Background of the Invention]

Most commonly used platens for impact printers are made of rubber. Therefore, since the steps of kneading, casting, vulcanization, release, and outer peripheral surface grinding are required to manufacture this, not only the number of steps is large and the cost is high, but also the weight is large.

Further, as disclosed in Japanese Patent Laid-Open No. 58-5821, for example, a low moment of inertia platen made of foamed resin is known.

The foamed resin platen has a specific gravity of the foamed resin of about 0.5g.
Since it is as small as / cm ³ , the driving torque of the platen can be reduced. This has advantages such as (1) high responsiveness and (2) small overshoot.

However, since the platen formed of only the foamed resin has a small strength on the outer peripheral surface of the platen body, when used as a platen for an impact type printer, a dent may occur on the outer peripheral surface of the platen body. Therefore, the conventional foamed resin is considered to be effective as a platen for non-impact printers, but there is a problem in adopting it as a platen for impact printers. On the other hand, in FIG. 10 of JP-A-59-182760, an outer layer and an intermediate layer of a platen having a cored bar are made of the same material, the outer layer is a hard dense elastic layer, and the intermediate layer is a foamed elastic layer. However, an example is shown. However, in this example, the mechanical bond strength between the core metal and the foam layer is not considered, and when the intermediate layer is the foam elastic layer, the physical contact area between the intermediate layer and the core metal is There was a concern that the mechanical bond strength could not be satisfactory because of the small amount of the metal, and the bond between the two was weakened when the platens were used repeatedly, and the peripheral edge of the core metal might not be peeled off.

[Object of the Invention]

The object of the present invention is to solve the above-mentioned problems of the prior art, to increase the strength of the outer peripheral surface of the platen body with respect to the printing striking force, to have good relaxation of the printing striking force, and to reduce the weight. It is an object of the present invention to provide a method for manufacturing a platen for a printer that can strongly bond with gold.

[Outline of Invention]

The present invention is a manufacturing method for forming a platen body,
Position the core metal of the platen in the center of the cavity of the mold, set the mold temperature to 40-70 ° C, and adjust the core temperature.
At 20 to 30 ° C, a polyether polyol obtained by adding an alkylene oxide to an aliphatic or aromatic amine or alcohol and an isocyanate together under high pressure collision mixing is injected into the cavity to foam. Then, in the surroundings of the molding die and the core metal, the foaming of the mixed liquid is suppressed by the molding die and the core metal having a temperature lower than the temperature of the reaction heat, and a non-foamed layer is formed. In a distant place, the foaming layer is formed by eliminating the foaming suppression effect of the above-mentioned mixed liquid by the mold and the cored bar lower than the reaction heat temperature, and the outer layer and the layer around the cored bar are the non-foaming layer and the inner layer is foamed. It is characterized in that it is adapted to obtain a layered platen.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the platen for an impact type printer of the present invention, and FIG. 2 shows an enlarged portion II in FIG.

The impact type printer platen shown in these figures is
The platen body 1 and the cored bar 5 provided at the center of the platen body 1 are provided.

The platen body 1 is made of foam resin,
The outer peripheral layer 2 of the platen body 1 and the layer 4 around the cored bar 5 are solid non-foamed layers, and the other portion 3 is a foamed layer.

Then, the platen body 1 is formed by a reaction injection molding method.
For example, it is molded as follows.

That is, as the material, a mixed liquid obtained by collision-mixing a composition containing polyol as a main component and an isocyanate under a high pressure of 100 to 200 kg / cm ³ is used.

This mixed liquid is injected into a molding die to be described later to which the cored bar 5 is fixed in advance to foam it at a foaming ratio of 2 to 3 times, and this is cooled in the molding die to be cured by reaction.

As a result, the portion in contact with the inner wall of the foam molding die,
That is, the outer peripheral layer 2 of the platen body 1 and the layer 4 in contact with the outer peripheral surface of the cored bar 5 are formed into a solid non-foamed layer having a thickness of 1 to 2 mm and a density of 0.7 to 1.2 g / cm ³ . Part 3 has a density of 0.1
Formed in a foam layer of ~ 0.4 g / cm ³ .

In order to form the outer peripheral layer 2 of the platen body 1 and the layer 4 around the core metal 5 as a high-strength solid non-foamed layer and the other portion 3 as a foamed layer, the composition containing a polyol as a main component is
A polyether polyol obtained by adding an alkylene oxide to an aliphatic or aromatic amine or alcohol, and a reaction accelerator (catalyst) composed of a tertiary amine and a tin compound, water, and a low boiling point alkyl halide. Etc., a foaming agent such as alkylene oxide-modified polydimethylsiloxane, and a pigment such as carbon black.

The isocyanate is 4,4'-diphenylmethane diisocyanate, polyphenylene polymethyl isocyanate or carbodiimide MDI, the composition containing the polyol as a main component is 100 wt%, the isocyanate is 110 to 190 wt%, the 100 Collide and mix at a pressure of ~ 200 kg / cm ² .

The temperature of the mold is 40-70 ℃, and the temperature of the core metal 5 is 20-30.
C. and the temperature of the mold and the core metal 5 is adjusted to be lower than the reaction temperature of 100 to 120.degree. C. after mixing the composition containing the polyol as a main component with the isocyanate, and the cavity 11 in the mold is
Then, a mixed liquid of the composition containing the above-mentioned polyol as a main component and an isocyanate is injected and reacted and cured.

Next, FIGS. 3 and 4 show an example of a molding die and a process of molding the platen for the impact printer shown in FIGS. 1 and 2 by using this molding die.

The mold includes a mold body 10, an upper mold 12, a lower mold 13, a mold clamping machine upper plate 18, a mold clamping machine lower plate 19, and a mixing head 24.
It has and.

A cylindrical cavity 11 for seamless printer molding is formed inside the mold body 10. A band heater (not shown) is attached to the outside of the die body 10 so that the temperature of the forming die can be adjusted to a predetermined temperature.

The upper mold 12 is connected to the mold body 10 via a connecting pin 14, and has a structure in which it is divided when the mold is opened. In addition, an air vent 20 is provided between the upper mold 12 and the mold body 10 when the mold is closed.
Are formed. The upper mold 12 is fixed to the upper mold mounting plate 16, and the upper mold mounting plate 16 is fixed to the upper plate 18 of the mold clamping machine. Further, the upper die 12 is provided with a support hole 23 for supporting the other end of the core metal 5.

The lower mold 13 is attached to a lower mold mounting plate 17 via a spacer 15, and the lower mold mounting plate 17 is fixed to a lower plate 19 of the mold clamping machine. Further, one end of the cored bar 5 can be supported on the lower die 13 via a stopper plate 21 and a nut 22. Further, the lower mold 13 has a runner 26 communicating with the cavity 11 and a gate 27 on the mating surface with the mold body 10.
Are formed.

The mixing head 24 is installed so as to be movable with respect to the lower mold 13, and is connected to the lower mold 13 with the injection port 25 facing the runner 26.

To mold the platen for impact type printer using this mold, first of all, close the mold on the lower mold 13 before closing the mold.
One end of the cored bar 5 is fixed via the 21 and the nut 22, and the cored bar 5 is set so as to be located at the center of the cavity 111.

Next, the upper die 12 and the die body 10 are lowered, the die is closed while the other end of the core metal 5 is inserted into the support hole 23 provided in the die 12, and a die clamping machine (not shown) ) Is operated in the mold clamping direction, and the mold is clamped via the mold clamping machine upper plate 18 and the mold clamping machine lower plate 19.

Further, the temperature of the mold is heated and maintained at 40 to 70 ° C. by the band heater, and the temperature of the core metal 5 is set to 20 to 30 ° C. The temperature of the cored bar is lower than that of the mold because the volume of the cored bar 5 is smaller than that of the main body 10 as shown in FIG. This is because it is easy to reach the temperature of. If the mold temperature is lower than 40 ° C, the molded product becomes brittle, and if it exceeds 70 ° C, voids may occur in the molded product.

In the meantime, the composition containing the polyol as the main component and the isocyanate are collision-mixed by the mixing head 24 under a high pressure of 100 to 200 kg / cm ³ . This mixing head 24
13 and close the runner 26, as shown in FIG.
After inserting 25, a mixed solution of the composition containing polyol as a main component and isocyanate is injected from the injection port 25 into the cavity 11 in the mold body 10 through the runner 26 and the gate 27.

The material injected into the cavity 11 has a foaming ratio of 2
It foams up to 3 times and foams and hardens in the cavity 11. This foam hardening progresses from the lower side to the upper side in the cavity 11, whereby the air in the cavity 11 is pushed out of the mold from the air vent 20 formed between the mold body 10 and the upper mold 12.

When the material foams and hardens, it self-heats and foaming pressure is generated. These become more remarkable as the expansion ratio is increased. The expansion ratio increases as the amount of material injected increases and as the content of a foaming agent such as a low boiling point alkyl halide in the polyol composition increases. The expansion ratio can be freely adjusted, but in the platen for impact printer according to the present invention, it is preferably 2 to 3.
Doubled. The self-heating temperature in the cavity 11 is
The maximum is about 90 ℃, and the foaming pressure is about 8kg / cm.
^{Is 2} .

The foaming pressure presses the inner wall of the mold body 10 and the outer peripheral surface of the cored bar 5, and at the same time, the temperature of the molding die and the cored bar 5 is lower than the temperature of reaction heat, so that foaming of the material is suppressed. As a result, the outer peripheral layer 2 of the platen body 1 and the core metal 5
The surrounding layer 4 is a solid non-foamed layer. Here, the polyether polyol obtained by adding an alkylene oxide to an aliphatic or aromatic amine or alcohol used in the present invention has high thermal conductivity, which is a non-foamed layer and a core in contact with the mold body 10. This means that the self-heating of the molded product is easily transmitted to the mold body 10 and the core metal 5 through the non-foaming layer in contact with the gold 5, and a non-foaming layer having an appropriate thickness can be obtained. The density of this non-foamed layer is 0.7-1.2 g /
cm ³ and the thickness is 0.7-2.0 mm. On the other hand, inside the platen body 1, the cooling effect by the mold body 10 and the cored bar 5 is small, and there is no factor to suppress foaming, so the foaming agent is completely vaporized and becomes a foamed layer.

After foaming and curing, the molded product is held in the molding die for a predetermined time (about 3 to 5 minutes) and completely cooled and cured.

Next, as shown in FIG. 4, lower the mixing head 24
Move away from 13. Then, the mold clamping machine is operated in the mold clamping releasing direction, the upper mold 12 is raised through the mold clamping upper plate 18 and the upper mold mounting plate 16, and the mold body 10 is pulled up through the connecting pin 14, as shown in FIG. Mold opening is performed as shown.

At the time of this mold opening, the flash 28 formed at the position of the air vent 20 is removed from the molded product.

Next, the nut 22 and the stopper 21 that fix the core metal 5
And remove the platen for impact printer.

In the impact-type printer platen molded by the reaction injection molding method described above, the platen body 1 made of foam resin and the core 5 are integrated.

Further, since the outer peripheral layer 2 of the platen main body 1 is formed of a solid non-foamed layer, it has a high strength against a printing striking force, and moreover, the outer peripheral layer 2 of the platen main body 1 and the core metal 5 are provided inside the platen main body 1. Since the other portion 3 excluding the layer 4 around is formed in the foamed layer, the print striking force is satisfactorily relaxed.

Further, since the layer 4 around the cored bar 5 is formed as a solid non-foamed layer, the platen body 1 and the cored bar 5 are strongly bonded.

Next, FIG. 5 shows another embodiment of the present invention.

As shown in FIG. 5, the cored bar 30 is a solid shaft intermediate part 31.
And flanges 32 and 33 integrally formed at both ends, and support shafts 34 and 35 projecting from the ends of the flanges 32 and 33, respectively, through the flanges 32 and 33. The platen body 1 and the cored bar 30 are strongly joined together.

The other structure of the embodiment shown in FIG. 5 is the same as that of the embodiment shown in FIGS. 1 and 2.

〔The invention's effect〕

As described in detail above, the present invention is a manufacturing method for molding a platen body, in which the core metal of the platen is located in the center of the cavity of the mold and the temperature of the mold is set to 40
To 70 ° C, the temperature of the core metal is 20 to 30 ° C, and a polyether polyol obtained by adding an alkylene oxide to an aliphatic or aromatic amine or alcohol.
A mixed solution obtained by high-pressure collision mixing with isocyanate is injected into the cavity to foam, and in the surroundings of the molding die and the core metal, a mixture of the mixed liquid is formed by a molding die and a core metal having a temperature lower than the temperature of reaction heat. Suppresses foaming to form a non-foaming layer, and at a location away from the mold and the core metal, foams by eliminating the foaming suppressing effect of the mixed liquid by the mold and core metal lower than the temperature of reaction heat. By forming a layer, a platen is obtained in which the outer peripheral layer and the layer around the core metal are non-foamed layers and the inner layer is the foamed layer. Especially, the non-foamed layer around the core metal strongly bonds the platen body to the core metal. And a highly reliable platen can be obtained.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the platen for impact type printer of the present invention, FIG. 2 is an enlarged view of a portion II in FIG. 1, and FIG. 3 is a platen for impact type printer shown in FIG. Longitudinal cross-sectional view of the mold closed state of the molding die for forming
FIG. 4 is a view showing a mold opening state of the molding die, and FIG. 5 is a vertical sectional view showing another embodiment of the platen for impact printer of the present invention. 1 ... Platen body, 2 ... Peripheral layer that is a non-foaming layer of the platen body, 3 ... Foaming layer inside the platen body, 4 ...
… Layers around the core, 5,30… Core,

Claims (1)

[Claims] 1. A manufacturing method for molding a platen body, wherein a cored bar of the platen is located at a central portion of a cavity of a mold, the mold temperature is 40 to 70 ° C., and the core bar temperature is 20 ° C. ~
30 ° C., aliphatic or aromatic amine, or a polyether polyol obtained by adding an alkylene oxide to an alcohol, and a high pressure collision mixed isocyanate, a mixture solution is injected into the cavity to foam, Around the molding die and the core metal, the foaming of the mixed liquid is suppressed by the molding die and the core metal having a temperature lower than the temperature of reaction heat to form a non-foamed layer, and the mold and the core metal are separated from each other. In place, a foam layer is formed by eliminating the foaming suppression effect of the above-mentioned mixed liquid by the mold and the core metal having a temperature lower than the heat of reaction, and the outer peripheral layer and the layer around the core metal are the non-foaming layer and the inner layer is the foam layer. A method for manufacturing a platen for an impact type printer, which is characterized in that a platen made is obtained.