CN111283978B

CN111283978B - Heating device, peripheral apparatus and method of controlling such peripheral apparatus

Info

Publication number: CN111283978B
Application number: CN201811494616.3A
Authority: CN
Inventors: 迈克·达布瑞兹
Original assignee: Vareplest Co ltd
Current assignee: Vareplest Co ltd
Priority date: 2018-12-07
Filing date: 2018-12-07
Publication date: 2022-03-01
Anticipated expiration: 2038-12-07
Also published as: CN111283978A

Abstract

The invention relates to a heating device for heating at least a part of the surface of at least one tool half (60, 62) of an injection molding tool. The heating device comprises at least one gas heater (8) having an inlet (11) and an outlet (12). Furthermore, at least one hot air feedback device is provided having an inlet opening (41) and an outlet opening (46), the outlet opening (46) of which is in fluid communication with the inlet opening (11) of the gas heater (8). In order to design the heating device so as to be maintenance-free, the hot air feedback device has, between its inlet opening (41) and outlet opening (46), an injection pump (42), which injection pump (42) is provided with a pressure gas connection (43), so that, in operation, air is sucked in at the inlet opening (41) and a mixture of sucked-in air and gas supplied through the pressure gas connection is discharged at the outlet opening (46). In addition, the invention also relates to a peripheral device with the heating device and the robot, and a method for controlling the peripheral device.

Description

Heating device, peripheral apparatus and method of controlling such peripheral apparatus

Technical Field

The invention relates to a heating device for heating at least a part of the surface of at least one tool half of an injection molding tool; a peripheral device for an injection molding machine; and a method for controlling such a peripheral device.

Background

From the prior art DE 102013014313 a1, the concept is known that, in order to improve the quality of injection-molded parts produced using a plastic injection-molding machine, at least a part of the surface of the tool half of the injection-molding tool is preheated for the open tool by means of a hot-air flow generated by a heating device, wherein the hot-air flow delivers a part of its thermal energy to the tool. In order to achieve rapid heating and high energy efficiency, it is proposed in particular to guide the air flow at least partially in a circulating manner, for which purpose a hot air feedback device is provided, and for which purpose a bell-shaped member is further used. This concept has proven to function well in practice.

Disclosure of Invention

Starting from this, the object of the invention is to further develop a generic heating device in order to further increase its utility and, in particular, to enable maintenance-free operation as possible. Furthermore, a compact design should be possible.

This object is achieved by a heating device according to the invention. In addition, a peripheral device for an injection molding machine having a heating device is also provided in the present invention, and a preferred method for driving such a peripheral device is provided.

As with conventional heating devices, the air used to heat the tool is directed in a circulating manner. That is, a hot air feedback device (Warumluft-Ru ckf u hreinrichtung) is provided. The hot air feedback device necessarily has a circulation device

According to the invention, the circulation device is configured as a jet pump which generally operates according to the venturi principle. Ordinary compressed air can be used as the driving jet. For this purpose, compressed air can be used which is normally already present in the production environment. This means that the ejector pump has a pressure gas connection. As will be seen later, in this way the hot air feedback device can be realized very compactly in the form of a heating head, and in particular without movable parts, thereby being able to operate substantially maintenance-free even if it is exposed to high temperatures.

As in the prior art, the heating device preferably has a bell-shaped member, since very high efficiencies can be achieved thereby.

Since the heating device is to be supplied with air continuously during operation, depending on the system requirements, an exhaust device should be provided, which can be achieved in particular by providing an exhaust opening. This can lead to predictable hot air losses. However, the advantages provided by using the hot air feedback device according to the invention are much greater than the losses of such hot air.

According to the peripheral device of the invention, which has the aforementioned heating device, the element with poor thermal conductivity (for example in the form of a layer of refractory clay) outside the region of the tool half preferably has a contact surface on which a bell-shaped member of the heating device can be arranged when the bell-shaped member is located outside the tool half. The heating device can thereby maintain the temperature during the injection molding process (Spritzvorgang), so that on the one hand a high energy efficiency and on the other hand a short cycle time is achieved. It is advantageous here that the thermal power of the heating device is smaller in the state in which the bell-shaped member is placed on the contact surface than in the state in which the bell-shaped member is placed on the surface of the tool half. It is particularly preferred here that both the amount of pressurized gas supplied and the electrical heating power are reduced in the state in which the bell-shaped member is placed on the contact surface.

Preferred embodiments and further advantages are obtained by the embodiments described in detail with reference to the accompanying drawings.

Brief Description of Drawings

The present invention will now be described in detail according to embodiments with reference to the accompanying drawings. Shown in the attached drawings:

FIG. 1 is a heating tip shown in perspective view;

FIG. 2 is a view of the heating tip of FIG. 1 from another perspective;

FIG. 3 is a view of the heater head shown in FIG. 2 partially planed;

FIG. 4 is a plan view of the heating tip of FIG. 1, as viewed in the direction R1 shown in FIG. 1;

FIG. 5 is a plan view of the heating tip of FIG. 1, as viewed in the direction R2 shown in FIG. 1;

figure 6 is a plan view of the heating tip of figure 1, looking in the direction R3 shown in figure 1;

FIG. 7 is a cross-sectional view along the plane A-A in FIG. 4;

FIG. 8 is a cross-sectional view along the plane B-B in FIG. 5;

FIG. 9 is a detail view of D1 in FIG. 8;

FIG. 10 is a detail view of D2 in FIG. 8;

FIG. 11 is a diagrammatic sectional view through an injection molding machine in a first operating condition;

FIG. 12 is a view of the injection molding machine of FIG. 11 in a transition state;

FIG. 13 is a view of the injection molding machine of FIGS. 11 and 12 in a second operating condition;

FIG. 14 is a view of the injection molding machine of FIGS. 11-13 in a third operating condition;

FIG. 15 is another embodiment of the peripheral device shown in FIGS. 11-14;

fig. 16 to 20 show various variants of the bell-shaped element nozzle unit.

List of reference numerals

5. 5' heating head

8 gas heater

9 protective sleeve

10 heating element

11 inlet

12 outlet

20 nozzle element

22 inner space

24 discharge opening

26 air guide plate

30 Bell-shaped member

32 exhaust port

34 side cover

40 tubes of a hot air feedback device

41 inlet opening of a hot air feedback device

42 jet pump

43 pressure gas joint

44 annular duct with discharge nozzle

45 ring-shaped opening

46 exit of first hot air feedback device

47 connecting chamber

48 heating body

50 robot

52 connecting plate

54. 54' spring unit

60 stationary tool half

62 removable tool halves

64 plasticizing unit

66. 66' elements with contact surfaces

66a, 66 a' contact surface

70 bell-shaped member-nozzle-unit

Detailed Description

Fig. 1 to 10 show an embodiment of a heating device according to the invention in the form of a heating head 5 in different views and illustrations. In describing the heating tip 5, reference is made to all of the accompanying drawings. Preferably, the heating device is constructed in the form of a compact, inherently rigid heating head 5, as shown in the drawings herein.

As mentioned above, the heating head 5 is used to heat at least a part of the surface of the tool half of the injection molding tool. The heating head 5 has a gas heater 8, which gas heater 8 is composed of a hollow cylindrical sheath 9 and an electric heating element 10 (which is also referred to as a heating cartridge) accommodated in the sheath. The gas heater 8 has an inlet 11 and an outlet 12 (these inlets and outlets coincide with the inlets and outlets of the heating element 10).

A nozzle element 20 is provided which is mounted on the jacket 9 of the gas heater 8. The outlet 12 of the gas heater 8 opens into the inner space 22 of the nozzle element 20. In the embodiment shown, the inner space 22 is surrounded by a conically extending jacket and ends at the discharge opening 24. In the embodiment shown, the nozzle element 20 preferably also has an air guide plate 26, in which air guide plate 26 the discharge opening 24 is located. In the embodiment shown, the gas guide plate 26 is designed to be planar and perpendicular to the longitudinal extent of the gas heater 8. In the illustrated embodiment, the air guide plate 26 has the shape of a circular disk (kreisscheib).

The gas heater 8 also carries a bell member 30. If the base of the bell member 30 is composed of a hard material, such as steel, it is preferred that the bell member have a skirt 34 composed of a relatively soft material, such as aluminum, carried by the base. The (here circular) edge of the bell-shaped member defined by the sideshield 34 is planar. As can be seen from fig. 10, the bell-shaped element is spaced apart from the gas guide plate 26 in the axial direction of the gas heater 8 by an edge defined by the edge skirt 34, preferably by a distance a of a few millimeters. In the absence of a sideshield, the spacing a is then defined by the edge position of the base of the bell-shaped member. It follows that when the bell-shaped member 30 is placed on a planar surface, the air guide plate 26 is spaced from the surface, and the spacing is a.

In the bell member 30, preferably in a side region thereof, an exhaust port 32 is provided. In principle, only one air outlet 32 can be provided, but it is generally still preferred to provide a plurality of air outlets 32. The function of such exhaust ports 32 will be explained below.

Finally, the heating head 5 has a hot air feedback device. The hot air feedback device serves to return and reuse a portion of the heated air (which is introduced into the space surrounded by the bell member 30 by the gas heater 8) in order to save energy. In the embodiment shown, two such hot air feedback devices are provided, however in principle only one such hot air feedback device may be provided or more than two such hot air feedback devices may be provided. For the sake of simplicity of language, the expression hot air feedback device is also used hereinafter only.

The hot air feedback device extends between the bell member 30 and a hollow body 48 surrounding the connection chamber 47. The inlet 11 of the heating element 10 is delimited on the connection chamber 47 such that air flows from the connection chamber 47 into the heating element if appropriate pressure conditions exist. The hot air feedback device has a tube 40 extending from the bell member 30 and an ejector pump 42. The bell member 30 has a tube opening (Durchbrechung) defining an inlet opening 41 for the hot air feedback device. The tube can also extend to the inside of the bell member 30, but this is not the case in the embodiment shown. An outlet 46 of the hot air feedback device, which is arranged downstream of the ejector pump 42, opens into a connecting chamber 47. The jet pump is a rigid component.

The construction of the jet pump 42 will now be described with particular reference to fig. 9. Jet pumps of this type are known in the art and generally operate according to the venturi principle or the Bernoulli (Bernoulli) principle. The ejector pump 42 has a pressure gas connection 43 adapted to be connected to a source of standard pressure gas at the production site. Generally, a regulating valve is connected between the pressure gas source and the pressure gas connection 43, which regulating valve is however not shown in the figures. The basic principle of the ejector pump 42 is that a directed pressure gas beam is generated, which has a moving component in the direction of the outlet. To achieve this, a number of different configurations known in the art can be used. In the embodiment shown, the annular line 44 connected to the pressure gas connection 43 is provided with an annular opening 45, the annular opening 45 forming a discharge nozzle. In the axial direction, the annular opening 45 is offset in the direction away from the opening 46 towards the centre of the annular duct 44, so that a flow direction indicated by the arrow is generated. In accordance with known fluid mechanics principles, the pressurized gas thus directed "entrains (mitrei β en)" ambient air, so that an overpressure occurs at the outlet 46 and a vacuum occurs at the inlet 41. That is, the hot air feedback device draws in hot air from the bell member 30 and presses a mixture of the drawn-in hot air and the supplied pressure gas (pressurized gas) into the connection chamber 47, which mixture flows from this connection chamber 47 into the bell member 30 through the heating element 10 of the gas heater 8 due to the existing overpressure.

During heating of the surface, in particular of the injection-molding tool, the edge of the bell-shaped member, which can be configured in particular by the sideshield 34, rests on the surface, thereby forming a closed space. Since the fresh air is continuously introduced into the system in the form of pressurized gas (or in principle also other pressurized gases), it is necessary to provide a venting device, if not the overall pressure of the system would continue to increase. For this purpose, the exhaust port 32 is used.

It can be seen that the hot air feedback device 40 can be implemented completely without movable parts and can therefore work maintenance-free. Furthermore, it can resist high temperatures, which makes it possible for the heating head 5 to be constructed very compactly.

A preferred manner of the intended use of the foregoing heating device will now be described with reference to figures 11 to 14. It should also be noted here that, in principle, a heating device which is otherwise designed (and which does not use a jet pump) can also be operated accordingly, but the combination of the heating device according to the invention and the method according to the invention described so far is particularly advantageous in use.

Fig. 11 shows, in high-level overview, a cross-sectional view through an injection molding machine having a stationary tool half 60 and a movable tool half 62. The plasticizing unit 64 is used to inject liquefied plastic into the openings of the stationary tool halves.

A heating device, i.e. a heating head 5, is provided for heating at least a part of the surface of the stationary tool half 60 prior to the injection molding process. Of course, it is also possible to arrange the heating head 5 in such a way that it heats a part of the surface of the movable tool half 62. In the illustrated embodiment, heating tip 5 is configured in the manner previously described. In order to be able to move heating head 5 between tool halves 60, 62 and in order to be able to bring the edge of bell-shaped member 30 into contact with the surface of stationary tool half 60, robot 50 is provided. Such robots 50 are also commonly referred to as "treatment devices". Robot 50 carries an attachment plate 52, which attachment plate 52 carries heating head 5 by means of a spring unit 54. Furthermore, an element 66 having a contact surface 66a is provided, which element 66 is arranged outside the region of the two tool halves 60, 62. The element 66 is preferably composed of a heat resistant material having poor thermal conductivity and/or large heat capacity. Thus, the element 66 can be, for example, a heat-resistant clay element.

Fig. 1 shows the tool just opened, for example because a previously injection molded part has just been removed (not shown). In this state, the bell-shaped member 30 is placed on the contact face 66a, and the heating head 5 is in a ready state in which the heating element 10 is operated with reduced power. Generally, in this case, the pressure gas supply is also adjusted downward to the ejector pump 42. However, since the bell member 30 is in contact with the contact surface 66a, no heat energy is unnecessarily lost.

In a subsequent method step (fig. 12), the heating head 5 is moved between the two tool halves 60, 62 and subsequently (fig. 13) the edge of the bell-shaped member is brought into contact with the surface of the stationary tool half 60. In this case, the spring unit 54 serves as a force limiting means. In this state, the operation of the heating head 5 is normally adjusted upward, that is, the power consumption of the heating element 10 rises, and the amount of the pressure gas to be supplied rises. By means of the hot air stream discharged from the outlet opening 24, a part of the surface of the tool half 60 is heated, in particular in the region of the air guide plate 26, wherein only a narrow gap exists between the air guide plate 26 and the tool surface. After the heating process is completed, the heating tip is removed from the region between the two tool halves.

The tool is now closed and the injection process is started. During this time, heating tip 5 is again in the position shown in figure 11. That is, the bell member 30 is placed on the contact surface 66 a. After the injection process is completed, portions of the tool halves 60, 62 are cooled by means of cooling channels, as is known in the art. This is not shown in the drawings.

As shown in fig. 15, it is possible to move the two heating heads 5, 5' into the region between the two tool halves by means of a robot 50. In order to keep the robot-heating head assembly as simple as possible, in this case the movement capability of the movable tool halves can be utilized in order to be able to bring the two bell members 30 into contact with the tool surface. In this case, the two elements 66, 66 ' with the contact surfaces 66a, 66a ' should be realized to be movable in order to enable the two heating tips 5, 5 ' to be in a state corresponding to fig. 11. Alternatively, at least one of the two heating heads may be arranged on the connecting plate 52 so as to be actively movable — in the tool closing direction — for example, by means of at least one pneumatic piston-cylinder unit.

The desired shape of the bell-shaped member 30 and the desired shape of the nozzle element 20 can vary greatly depending on the injection-molded part to be produced. It is therefore preferred to manufacture the element at least in sections in a heat-resistant material using a 3D printing method, so that a plurality of different heating heads suitable for solving the above-mentioned problems can be formed using a basic element consisting of the hollow body 48 and the gas heater 8. In this case, it is particularly advantageous if the bell-shaped element and the nozzle form a bell-shaped element nozzle unit 70, which can be fastened to the gas heater 8 in a simple manner, wherein the fastening can be achieved, for example, by simple snap-on and latching.

Fig. 16 to 20 show examples of such bell-shaped member-nozzle-units 70. The bell-shaped member nozzle unit 70 shown in fig. 16 is essentially constructed such that, after it is arranged on the gas heater 8, a heating head 5 as shown in fig. 1 to 10 results. If desired, a sideshield can also be provided on the base of the bell member.

The embodiment shown in fig. 17 has two discharge openings 24, as does the embodiment shown in fig. 20. As can be seen, for example, from fig. 18, some applications are also possible in which the nozzle element 20 projects deeper into the respective tool half than the bell-shaped member 30.

Claims

1. A heating device for heating at least a portion of a surface of at least one tool half (60, 62) of an injection molding tool, the heating device comprising:

at least one gas heater (8) having an inlet (11) and an outlet (12),

at least one hot air feedback device having an inlet (41) and an outlet (46), the outlet (46) of the hot air feedback device being in fluid communication with the inlet (11) of the gas heater (8),

characterized in that the hot air feedback device has an ejector pump (42) between its inlet opening (41) and outlet opening (46), the ejector pump (42) being provided with a pressure gas connection (43) such that, in operation, air is sucked in at the inlet opening (41) and a mixture of sucked in air and gas supplied through the pressure gas connection is discharged at the outlet opening (46).

2. The heating device as claimed in claim 1, characterized in that the gas heater (8) and the jet pump (42) are rigidly coupled to one another and form a part which can be moved into the heating head (5, 5') between the opened tool halves (60, 62).

3. A heating device as claimed in claim 2, characterized in that the heating head (5, 5') further has a bell-shaped member (30), wherein the bell-shaped member (30) has an opening which forms the inlet opening (41) of the hot air feedback device or through which a portion of the hot air feedback device passes, such that the inlet opening (41) of the hot air feedback device is located in the area enclosed by the bell-shaped member.

4. A heating device as claimed in claim 3, wherein said bell-shaped member (30) further has at least one air outlet (32).

5. A heating device as claimed in claim 3 or 4, characterized in that a nozzle element (20) is arranged downstream of the at least one gas heater (8), through which nozzle element (20) the air flowing out of the gas heater (8) flows.

6. A heating device according to claim 5, characterized in that the nozzle element (20) has an air guide plate (26).

7. The heating device according to claim 5, characterized in that the bell-shaped member (30) and the nozzle element (20) form a bell-shaped member-nozzle-unit (70) which is exchangeably arranged on the gas heater (8).

8. The heating device according to claim 6, characterized in that the bell-shaped member (30) and the nozzle element (20) form a bell-shaped member-nozzle-unit (70) which is exchangeably arranged on the gas heater (8).

9. Heating device according to claim 7, wherein the bell-shaped member-nozzle-unit (70) is constructed in one piece.

10. Heating device according to claim 8, wherein the bell-shaped member-nozzle-unit (70) is constructed in one piece.

11. Heating device according to claim 7, wherein the bell-shaped member-nozzle-unit (70) is at least partially manufactured in a 3D printing method.

12. Heating device according to any one of claims 8 to 10, wherein the bell-shaped member-nozzle-unit (70) is at least partially manufactured in a 3D printing method.

13. A peripheral apparatus for an injection molding machine, comprising:

heating device for heating at least a part of a surface of at least one tool half (60, 62) of an injection molding tool, the heating device having:

at least one gas heater having an inlet and an outlet,

at least one hot air feedback device having an inlet and an outlet, the outlet of the hot air feedback device being in fluid communication with the inlet of the gas heater, an

A bell-shaped member, wherein the bell-shaped member has an opening forming an inlet opening of the hot air feedback device, or wherein a portion of the hot air feedback device passes through the opening such that the inlet opening of the hot air feedback device is located in an area surrounded by the bell-shaped member,

and

a robot (50) on which the heating device is coupled such that the robot can bring the bell-shaped member into contact with one of the two surfaces and at a location outside the area between the two tool halves,

characterized in that the peripheral device also has an element (66), the element (66) having a contact face (66a), the bell-shaped member being contactable with the contact face (66a) by means of the robot (50).

14. The peripheral device of claim 13, wherein the heating means are designed according to at least one of claims 1 to 12.

15. The peripheral device according to claim 13, wherein the heating means are connected to a connection plate (52) by means of spring units (54, 54'), the connection plate (52) being coupled to the robot.

16. The peripheral device according to claim 14, characterized in that the heating means are connected to a connection plate (52) by means of spring units (54, 54'), the connection plate (52) being coupled to the robot.

17. The peripheral device of any of claims 13 to 16, wherein two oppositely oriented heating means are coupled with the robot such that part of the surface of both tool halves can be heated.

18. A method of controlling a peripheral device as claimed in any one of claims 13 to 17, wherein the heating means are driven such that the thermal power is less when the bell member is placed on the contact face than when the bell member is placed on the tool half face.