JPS6126163Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a temperature control device for a thermoplastic film heat sealing machine, and particularly relates to a heat sealing machine in which heat sealing is performed not by hot air but by a heat sealer heated by hot air. This invention relates to a device for controlling the temperature of supplied hot air.

In this type of heat sealing machine, it is customary to control the optimal heat sealing by measuring the temperature of supplied hot air, rather than directly measuring the temperature of the heat sealer. In this case, the supplied hot air temperature is the temperature of the heat sealer that is continuously performing heat sealing work.
℃, it needs to be higher than that, about 180℃. If only the heat sealing operation is interrupted while the hot air supply continues, the temperature of the heat sealer will rise from 150°C to the supplied hot air temperature (approximately 180°C). When the heat-sealing operation is restarted, the film is heat-sealed with the heat-sealer that has been heated to the hot air temperature. Naturally, the film is heated above the proper heat-sealing temperature, causing the film to melt and create holes. On the other hand, if the supply of hot air was completely stopped every time the supply of the packaged objects was interrupted due to a relatively short temporary interruption of the heat sealing operation or an unexpected cause, it would be difficult to proceed with the next normal operation. It is undesirable that it takes time to heat the heat sealer to an appropriate temperature when it is used, and that defective products occur before stable heat sealing is achieved.

Therefore, in the conventional apparatus, when there is no supply of objects to be packaged, a method has been adopted in which the temperature of the hot air is controlled to some extent proportionally using a slider resistance. However, this method often relies on the experience and intuition of the worker, which not only puts a mental burden on the worker, but also
It is unavoidable that the amount of control is too large or too small, resulting in drawbacks such as holes in the film due to overheating of the heat sealer or poor heat sealing due to insufficient heat at the start of the next operation.

The present invention was developed in view of the above points, and is a heat sealer that lowers the temperature of the hot air in situations where the supply of packaged objects is interrupted and can constantly maintain the optimum temperature for heat sealing the heat sealer. The present invention provides a supply hot air control device for a machine.

The present invention is a control device for a heat sealing machine that seals a thermoplastic film using a heat sealer heated by hot air, and includes a heat-sensitive resistor whose resistance value decreases as the temperature of the hot air increases. , a resistor having a resistance value provided so as to form a parallel circuit with the heat-sensitive resistor, and a signal from a means for detecting the presence or absence of supply of the packaged object to ensure that the supply of the packaged object is continued. a hot air temperature detection means having a switch means for disconnecting the resistor and the heat-sensitive resistor when the supply of the packaged body is interrupted and for connecting the resistor and the heat-sensitive resistor when the supply of the packaged body is interrupted; It is characterized by comprising a temperature controller that compares the temperature indicated as a resistance value in the hot air temperature detection means with a set reference temperature of the hot air and outputs a control signal to the hot air supply means. This invention relates to a temperature control device for a heat sealing machine.

Fig. 1 is a diagram showing a flow sheet of the control device of the present invention, Fig. 2 is a block diagram showing an embodiment of the device of the present invention and a part thereof is shown as a circuit, and Fig. 3 is a diagram showing the hot air flow by the device of the present invention. and a temperature diagram of a heat sealer.

As can be understood from Figure 1, the basic configuration of the present invention is to continuously detect the hot air temperature during normal heat sealing operation, and to constantly compare the detected temperature with the reference temperature of the hot air. In addition to maintaining the supplied hot air at the optimum temperature for heat sealing, when the supply of the packaged object is interrupted and the external situation changes, specific conditions are automatically added to the hot air temperature detection means, and a specific condition is automatically added to the hot air temperature detection means. Therefore, the temperature of the hot air from the hot air supply means is controlled to the optimum temperature even though the initially set reference temperature remains unchanged.

Next, a more detailed explanation will be given with reference to FIG. Second
The figure shows an embodiment featuring a hot air temperature detection means 2; a heat sensitive resistor 4 installed near the hot air outlet in the packaging section 8 of the heat sealing machine.
, a resistor 5 provided to form a parallel circuit with the heat-sensitive resistor 4, and a resistor 5 connected in series with the resistor 5 and installed at another appropriate location of the heat sealing machine to form a packaged object. a hot air temperature detecting means 2 comprising a switch 6 which connects the resistor 5 to the circuit in response to a signal from the packaged object supply detection means 3, 3' which detects whether or not the packaged object is supplied; a temperature regulator 1 that compares the temperature indicated as a resistance value in the hot air temperature detection means 2 with a reference temperature of the hot air and outputs a control signal; controlled by the control signal from the temperature regulator 1; a hot air supply means 7; a supply detection means 3, 3' for detecting whether or not the packaged object is being supplied, which is composed of a photoelectric conversion element or a self-holding relay for a fixed period of time connected thereto;
It is made up of.

The resistance value of the heat sensitive resistor 4 changes with temperature changes, and in this case a thermistor with a negative characteristic is used, whose resistance value decreases as the temperature rises. When the articles to be packaged are continuously supplied and heat sealing is continuous, the temperature change of the supplied hot air is detected only by the heat sensitive resistor 4 and the hot air supply means 7 is controlled by the temperature regulator 1, but as mentioned above, if the supply of the articles to be packaged is interrupted, the temperature of the heat sealer rises to the supplied hot air temperature, so the supplied hot air temperature must be kept constant at a temperature considerably lower than the reference temperature.
The constant temperature here means the optimum temperature of the heat sealer when heat sealing. In order to achieve the above object, in this invention, when the supply of the packaged material is interrupted, the temperature of the supplied hot air drops to the heat sealer temperature suitable for heat sealing (150
When the temperature reaches the reference temperature (180° C.) of hot air set in the temperature controller, the hot air temperature detection means 2 detects a high virtual air temperature different from the actual temperature as if it were the reference temperature (180° C.) of hot air set in the temperature controller.
Configure.

That is, if the resistor 5 is connected in parallel to the heat-sensitive resistor 4, the combined resistance value will be lower than the resistance value of the heat-sensitive resistor 4 alone, and if the resistance value of the resistor 5 is selected appropriately. Even if the heat sensitive resistor 4 detects a temperature of 150℃, the temperature of the hot air temperature detection means 2 as a whole is 180℃.
It shows the resistance value in °C and outputs it to the temperature controller 1.

Therefore, when continuous heat sealing is interrupted, the switch 6 connects the resistor 5 in parallel with the heat sensitive resistor 4, and at that moment the hot air temperature decreases.
Since the temperature is 180°C, the temperature indicated by the hot air temperature detection means 2 is 210°C. Since this temperature is higher than the standard temperature of 180℃ instructed to temperature controller 1, temperature controller 1
sends a control signal to the hot air supply means 7 to stop or reduce the supply of hot air to lower the temperature detected by the heat sensitive resistor 4. And the hot air temperature is 150
It becomes stable when the temperature reaches ℃. Note that the resistor 5 has an appropriate value depending on the type of film, etc.

In addition, in the above explanation, in order to make it easier to understand, the reference temperature and the temperature of the supplied hot air to be controlled are described as completely matching, but in reality, it is within a certain allowable temperature range above and below the reference temperature. control.

Furthermore, if two stages of heat generating bodies are prepared as the hot air supply means 7, one of which is used as the main body to constantly supply hot air, and the other is used as a sub-stage, and control is performed on this sub-stage, more accurate control can be achieved. It can be done.

[Brief explanation of the drawing]

Fig. 1 is a flow sheet for explaining the principle of the invention, Fig. 2 is a block diagram showing an example of the invention, and Fig. 3 is a diagram showing the temperature curves of hot air and heat sealer in each situation. be. In the figure, 1 is a temperature controller, 2 is a hot air temperature detection means,
Reference numerals 3 and 3' indicate means for detecting whether or not a packaged object is supplied, 4 a heat-sensitive resistor, 5 a resistor, 6 a switch, 7 a hot air supply means, and 8 a packaging section, respectively.

Claims (1)

[Claims for Utility Model Registration] A control device for a heat sealing machine that seals a thermoplastic film using a heat sealer heated by hot air, which is a heat-sensitive device whose resistance value decreases as the temperature of the hot air increases. a resistor having a resistance value provided to form a parallel circuit with the heat-sensitive resistor, and a signal from a means for detecting whether or not the packaged object is supplied. hot air having a switch means for disconnecting the resistor and the heat-sensitive resistor when the supply of the packaged body continues and for connecting the resistor and the heat-sensitive resistor when the supply of the packaged body is interrupted; Comprised of a temperature detection means and a temperature controller that compares the temperature indicated as a resistance value in the hot air temperature detection means with a set reference temperature of the hot air and outputs a control signal to the hot air supply means. A temperature control device for heat sealing machines featuring: