DE1479737B2 - METHOD AND DEVICE FOR MANUFACTURING ELECTRICALLY HEATABLE WATER TANKS FROM THERMOPLASTIC PLASTIC - Google Patents

Description

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The invention relates to a method and draw without affecting the compressive strength and shape

a device for producing electrical loading stability of the container can be reduced od

heatable water tanks made of thermoplastic disadvantages of the type described above - etv

Plastic with in this embedded curved with respect to the heat transfer - arise.

Jacketed tubular heating element together with temperature sensing device 5 This object is achieved according to the invention

the associated temperature switch. solved that the Mante bent into a loop

It is known to have a tubular heating element, bent in the shape of a loop, in addition to the temperature sensing device

metallic tubular heating element together with this one before the start of the known manufacturing process

thermally connected bimetal temperature controller with an insert connected hollow body

into the bottom of a pan-shaped io by blowing a tubular preform line;

Warming device made of thermoplastic against the inner wall of a split hollow shape;

to embed material for prepared meals and the like, streaked over the preform and during d <

by placing these parts in an associated molding or blowing in a position perpendicular and concentric

Injection mold inserted at the appropriate point to the longitudinal axis of the blow space of the hollow mold ue

and the plastic after it has been through 15 in at least the wall thickness of the water

heat was transferred to the flowable state, container corresponding distance of d <on all sides

is filled into the same or placed under high pressure on the inner wall of the blow chamber,

is injected. · Lie down during the subsequent blowing process

Since the floor is at every point around a small amount at the level of the tubular heating element

thicker than the - usually about 8 mm - 20 parts of the preform not just around the same as well

send - pipe diameter of the jacket pipe heater - the temperature sensor pipe tight and tight around, soi

pers and thus the thermally insulating itself also close when the blowing pressure is high

Plastic floor practically only over that in the area is enough on the wall of the blow chamber

the highest lying surface line of the jacket-facing side of the tubular heating element zi

tubular heating element, thinner plastic layer of useful 25 together, while the one connected to it without interruption

Able to give off heat, there is one subsequent to the loss and all other parts of the Voi

heat considerably increasing, unwanted heat moldings lay on the wall of the blow chamber

delivery in the area of this diametrically located, and consequently the shape of the water container ar

Take the surface line of the facing away from the material to be heated. ;

Metal tubular radiator over the thin 30 depending on the size of the gap between Mante

It forms a plastic layer as well as a build-up of heat on the unequal tubular heating element and the blow chamber wall

larger, remaining metal tube circumference. there a longer or shorter, circulating art

That these circumstances disadvantageously lead to a larger web of material, the thickness of which is about twice that of the container]

Corresponds to thermal stresses and strongly different Temv wall thicknesses. Especially in connection

peraturverteilungen both in the plastic and 35 to the jacket tube radiator sets this web bt

lead on the tubular heating element, it goes without saying that overpressure or underpressure occurs in the water

itself. Also, when this container is transferred, the otherwise associated with it

Arrangement on electric hot water storage tank, d. H. Expansion movements or contractions de

the same arrangement of a corresponding jacket water container perpendicular to the longitudinal axis of the container

tubular heater in a plastic as before 40 reaching resistance, so that it is at de

procured flange plate or bottom wall for blown, pressureless containers usual Wane

of an electric hot water storage tank cannot be strengthened. Requirement for the Au!

Change advantage. catch the mentioned container changes bf

Furthermore, it is known that a metallic man- greater water pressure should sometimes still be a problem

Telrohrheizkörper to be covered with a plastic 45 rigid connection of the tubular heating element end

and be in the water tank of a hot water tank, so that the tubular heating element loop

Can be installed freely to close the scale and water in a ring and thus no longer follow

to avoid corrosion on the radiator. can give.

Furthermore, a method for producing a The embedding of the tubular heater is ui

Hollow body made of thermoplastic material makes it safer to walk and a perfect rope

become known, in which in the plastic body with the more flowable the preform in the area de

Distance from the inner mold wall cores inserted tubular heater is made. This leaves sic

that can be achieved with the material during the blow molding process by inserting the into the hollow mold

be completely dressed. These cores are used after tubular heating elements equal to the hollow shape

which they are removed from the mold, support webs 55 is heated. Appropriately, the Au)

to form, which is then used for the later inclusion of heating of the tubular heating element electrically,

Parts not to be mentioned here are suitable. Furthermore, the dimensional stability of the water is

are. . holder under the conditions shown bi

With the pouring of such a core, pressurization is then to be greatest, whom

an object between the water tank and the jacket tube that determines the processing operation;

work step facilitated by the stands;

been. held and at right angles to the actual hold]

The invention is based on the object of a wall running so that bending stresses

Jacketed heating element and the temperature sensor of the goods in the same and adjacent to the latter

Temperature switch with the production of 65 manure parts of the water tank or parts de

Water tank same process step with a plastic sheathing of the tubular heating element

not to be avoided to a greater extent than for resistance to corrosion,

The location and course of the bridge is also insofer

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must be controlled, i.e. not expected to do so.

it can become that the same ratursn at the narrowest point, especially as a result of the drying up of the

of the gap, which for safety reasons more than a water tank, the temperature sensor tube of the

should be twice as large as the temperature switch with the tubular heating element - like

container wall thickness, will form by itself, ins- 5 already mentioned - in a thermally conductive connection

special not arranged in case of different lengths.

Enclosing ways of adjacent preform parts A according to the proposed method with off on the tubular heating element circumference, d. H. from the first plastic compound originating from the preform over contact point between the preform and the jacket-drawn jacket-tube heater protrudes up to the im tubular heating element made of in opposite circumferential io relation to the jacket tube circumference unequal narrowing directions up to the narrowest point of the gap. There is practically free space in the interior of the bridge it is therefore proposed in addition that the man water tank into it, so that about 90% of his Telrohrheizkörper along its circumference surrounded by a thin plastic casing of water Thermal stresses protruding into the air gap, but not surmounting them, and causing disadvantages Has bridging ridge, or the temperature 15 and temperature differences in the heat sensing device to be formed as a temperature sensor tube or surrounding jacket tube sections and in place of the burr on the circumference of the jacket plastic parts do not occur. The same basic pipe radiator in the direction of the air gap, however, it can also assign in a modified form. be applied in such a way that the distance

The flowing apart of the preform is 20 by a in a manner known per se in a then arranged in the direction of the shorter of the two circumferential groove of the hollow mold and pipe enclosing paths to be encased immediately before the narrowest point to be embedded by the preform the gap is braked during the blowing process and the thick-walled plastic ring is formed, a one-sided, to unwanted changes of which before the blowing process in place of the mentioned Web guiding, free flow through the plastic air gap between the blowing chamber wall and - the deformable, solid plastic mass through the preform surrounding - Maritel tubular heating element Gap is only arranged by the throttling effect, whereby it is on the one hand itself in a very slowly, if at all, and there the corresponding groove of the blow chamber known per se which is inserted quickly from the opposite direction, on the other hand an umlaudrushing one Meet plastic compound, as well as with this, 30 fende groove for tightly fitting reception of the jacket the heated ridge or temperature sensor tubular heater with but only part of it supports, there contains an intimate, firm and enduring scope. The rest of the same size or Enter into connection. slightly larger circumferential part of the radiator along with it

The wall thickness of the blown, pressureless container adjacent temperature sensor tube then protrudes into the with contents up to about 801 it is known that the actual blowing space of the hollow mold is inside it. the normally no more than about 1.5 to 3 mm, hollow shape and expediently also the heating element So that the heat transfer from the jacket pipe body are then heated up to radiator on the water content through the plastic ring equal to the preform one Speaking thin plastic layer in no stronger intimate connection with the same permitting temperature Dimensions is hindered as comparatively by a 40 before the preform is inflated itself Approximately the same thick layer of scale, since the heat against the blow chamber wall and the free radiator conductance the same are roughly equivalent. In the pteil lays as well as with the latter adjacent, free The rest of the plastic ring parts around the tubular heating element should be dense, solid and durable The plastic layer located there must be thinner than the connection. The connection will be special those of the water tank, as the corresponding 45 will be good if for the plastic ring and the pre-mass of the preform, the same materials are used when flowing around the preform, Jacketed heating elements pull apart, their softening points at the same temperature must than on the actual blow chamber wall. lie.

It should not go unmentioned that with such water the plastic ring covers it in advantageous

containers dispensed with the otherwise usual flange 50 way not only from the radiator to the outside

due to the fact that the smooth plastic and due to its thick walls prevent un-

Container wall or the heat dissipation from the radiator that is undesirable with plastic

drawn, carried by the container wall, but it increases - as before with the

Jacketed radiators cannot form scale. Jacketed radiators described - including the over-

and consequently not removed via a hand hole to 55 and vacuum resistance as well as dimensional stability of the

needs to be. The same applies to the radiator water tank,

regarding water corrosion. In the following the invention is based on hand

As a plastic material, two examples in connection with those in

point out the figurative representations that are definitely included for water tanks

Choose from sufficient, inexpensive polypropylene. 60 clarified in more detail. The different dar-

This has an expansion at around 160 ° C. Common features are the simple

point of interest. For the sake of clarity and for the sake of clarity, this temperature is also included

Jacketed heating element even then not reached, use the same reference numerals,

when water is brought to the boil in the container F i g. 1 shows a longitudinal section of half of a

should be, because the necessary temperature gradient 65 prepared hollow shape with tubular heating element

between the jacket pipe of the radiator and in the open and temperature sensor;

heating conceived water not more than zft ~ 20 ° C Fig. 2 shows the other half of the hollow form in the

amounts to. Condition immediately after the end of the blowing process;

F i g. 3 and 4 give an alternative solution in the same way and sequence as in FIGS. 1 and 2 again, a plastic ring being arranged in a circumferential groove of the hollow mold.

In Fig. 1, a loop-shaped tubular heating element 3 is in the blow chamber 1 of the hollow mold 2 together with Temperature sensor tube 4 of a temperature switch, not shown, leaving an air gap 5 used and a preform 6 made of polypropylene inserted before the start of blowing. For the latter is now only The heating of the hollow mold 2 and the tubular heating element 3 to blowing temperature is a prerequisite. '

During the blowing, according to FIG. 2 parts of the preform 6 from FIG. 1 around the circumference of the tubular heating element 3 placed in opposite directions with pulling apart and themselves in the air gap5 (from Fig. 1) between tubular heating elements 3 and Blasraumwandung 7 joined together to form a web 8 which is continuously in the continuous wall of the water container also emerged from the preform 6 (FIG. 1) 9 passes.

In the second example according to FIG. 3 and 4 is in the prepared hollow form 2 (FIG. 3), however Jacketed tubular heating element 3 together with temperature sensor tube 4 in the cross-sectional direction on approximately half the circumference in a circumferential inner groove 10 of a thick-walled Kunststöffringes 11, which in turn is in a ' is held in the Blasraumwandung 7 circumferential groove 12.

As can be seen from FIG. 4, the preform 6 (from FIG. 3) has accumulated during the blowing process the blow chamber wall 7 of the hollow mold 2 and in front of the exposed parts facing the blow chamber 1 of the tubular heating element 3, temperature sensor tube 4 and plastic ring 11 placed and used as a water tank 9 firmly connected to the latter.

Claims (11)

Patent claims: 1. Process for the production of electrically heatable water containers made of thermoplastic Plastic with a curved tubular heating element embedded in this, along with a temperature sensor of the associated temperature switch, characterized in that the tubular heating element bent into a loop (3) together with the temperature sensing device before the start of the known production a hollow body connected to an insert by blowing a tubular The preform is streaked over the preform (6) against the inner wall of a split hollow mold and during the blowing in a position perpendicular and concentric to the longitudinal axis of the Blowing space (1) of the hollow mold (2) and in at least one of the wall thickness of the water container corresponding distance on all sides from the inner wall of the blow chamber (1) will. 2. The method according to claim 1, characterized in that the tubular heating element (3) equal to the hollow mold (2) is heated. 3. The method according to claims 1 and 2, characterized in that the heating of the Jacketed heating element (3) takes place electrically. 4. The method according to claim 1, characterized in that that the distance is formed by an air gap (5). 5. The method according to claim 1, characterized in that the distance by an in in a manner known per se in a circumferential groove (12) of the hollow mold (2) and arranged by the preform (6) to be embedded, thick-walled plastic ring (11) is formed will. 6. Process according to claims 1 to 3 and 5, characterized in that for the KunststofMng (11) and the preform (6) materials are used whose softening points lie at the same temperature. 7. The method according to claims 1 to 3, 5 and 6, characterized in that for the Plastic ring (11) and the preform (6) the same material is used. 8. Device for performing the method according to claim 1, with a divided hollow shape, characterized in that between the ends of the insertable into the hollow mold (2) Jacketed heating element (3) a rigid connection is provided. 9. Device according to claims 1, 4 and 8, characterized in that the tubular heating element (3) has along its circumference a ridge protruding into the air gap (5) but not bridging it. 10. Device according to claims 1, 8 and 9, characterized in that the temperature sensing device designed as a temperature sensor tube (4) and in place of the ridge on the circumference of the tubular heating element (3) in the direction of Air gap (5) is arranged towards. 11. Device according to claims 5 and 8, characterized in that the plastic ring (11) has a circumferential inner groove (10) for receiving the tubular heating element (3). 1 sheet of drawings