JPH04412Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a temperature control device for a dummy impulse heater used in a silicone wrapper packaging machine, a bagging machine, a pouch filling machine, a pack filling machine, etc.

In an impulse sealing machine for plastic sheets in an automatic packaging machine, if pulse electricity is applied to the heater at a constant voltage and at a high frequency over a certain period of time, the temperature of the heater and the seal bar to which the heater is attached will remain. The heater temperature gradually increases due to the heat, making it impossible to obtain the optimum heater temperature, resulting in problems such as melting of the seal portion of the plastic sheet and shortening of the heater life due to red heat of the heater.

For this reason, in general, there are forced water cooling methods that pass water through the heater bars to saturate the residual heat at the lowest possible temperature, and forced air cooling methods that blow air onto the heater bars. For impulse sealing machines, it is mechanically difficult to use a forced water cooling method, and using a forced air cooling method increases air consumption, leading to increased costs.

In order to solve the above-mentioned problems, the present invention aims to provide an impulse heater temperature control device that can automatically obtain the optimum heater temperature when the heater is energized in pulses without using forced water cooling or forced air cooling.

The temperature control device of the present invention will be described below, but first an impulse sealing machine to which the present invention is applied will be described. Figure 1 shows this schematic configuration, which mainly consists of an upper rotating device Ru and a lower rotating device Rd, which are mechanically connected to the same drive source M and rotate synchronously. .

The upper rotating device Ru has multiple heater bars B (B ₁ to _{B 10} in the figure) that are manufactured with the same specifications and perform actual work.
(10 pieces) are provided on the circumferential surface of the rotating body. On the other hand, a heater receiving bar R is provided on the circumferential surface of the rotating body of the lower rotating device Rd at a position corresponding to the heater bar B.
A plurality of (10 R ₁ to R ₁₀ in the figure) are provided. And the upper and lower rotating devices Ru, Rd
The upper plastic sheet Fu and the lower plastic sheet Fd are sandwiched between them, and the articles to be packaged W ₁ to _{W 6} are individually sealed and cut as shown in FIG.

As shown in FIG. 3, the heater bar B is equipped with a seal heater Hs and a cutting heater Hc.
On the other hand, the power supply portion of the heater bar B has a power supply unit Q as shown in FIG. 4, and power is supplied from the power supply bar pedestal Qb via a brush Bu provided on the power supply unit Q.

When the upper rotating device Ru rotates, the heater bar B attached to it begins to descend as it approaches the heater energized position, and is configured with a cam mechanism so that it completely sandwiches the upper and lower plastic sheets Fu and Fd at the heater energized position. When the upper rotating device Ru is further rotated, the heater bar B gradually rises and moves away from the heater receiving bar R.

Incidentally, when the upper and lower rotating devices Ru, Rd rotate, the plastic sheets Fu, Fd and the packaged object W are automatically fed.

At the heater energization position, if the optimum voltage and energization time are given to the sealing heater Hs and the cutting heater Hc, respectively, the plastic sheets Fu and Fd are bonded and cut by heat, and the packaged object W is formed as shown in Fig. 2. is now wrapped in plastic sheets Fu and Fd.

In this way, the optimum pulse energization time (in this example, the heater applied voltage is fixed and the energization time is controlled, but the energization time is fixed and the applied voltage may be controlled) to obtain a sealing heater
Hs can be obtained by actually measuring the temperature immediately before the energization timing of the cutting heater Hc. However, in this invention, one dummy heater Dd is installed in addition to the sealing heater Hs and cutting heater Hc that perform actual work.
The heater for the dummy seal installed and included in this
By measuring the temperatures of Hds and the dummy cut heater Hdc, the optimum energization time for the heaters Hds and Hdc is obtained. As shown in Fig. 5, this dummy heater Dd is connected to the dummy seal heater Hds.
and a dummy cut heater Hdc, which are arranged at fixed positions other than the upper and lower rotating devices Ru and Rd driven by the drive source M shown in FIG.

When manufacturing the dummy seal heater Hds and the dummy cut heater Hdc included in the dummy heater Dd, they must be of the same size or have the same thermal time constant as the seal heater Hs and the cut heater Hc included in the heater bar B. It needs to be made in a similar shape.

Next, the temperature control device of the present invention will be explained with reference to FIG. The drive source M consists of a motor 101 and a reduction gear 102. The upper rotating device
As mentioned above, Ru is equipped with the heater bar 103, that is, a sealing heater and a cutting heater. 10
Reference numeral 4 denotes a timing cam that rotates once per pitch of movement distance of the heater bar 103. A timing detector 105 is turned on when the timing cam 104 is able to energize the heater.

106 is a thyristor into which power is input from the heater power source and supplies pulsed power to the power supply bar 100 (indicated as Qb in FIG. 4) and a dummy heater 110 (described later); 107 is a power supply control unit that receives power from a calculation unit 118 (described later); An energization command is given to the thyristor 106 at the timing of the timing detector 105 by the "heater energization time" value.

Reference numeral 108 denotes an electromagnetic contactor contact, which is turned on in response to a command from a heater bar rotation time measuring section 117, which will be described later, and supplies power to the transformer 109. 110 is a dummy heater to which the output voltage of the transformer 109 is applied, and 111 is a temperature detector made of, for example, a thermocouple, so that the output voltage changes as the temperature rises. 112 is an amplifier that amplifies the output voltage of this temperature detector 111. Reference numeral 113 denotes a reference value setting unit for setting a reference value for the heater energization time. 114 is an analog comparator for comparing the output voltages of the amplifier 112 and the reference value setting section;
14 is designed such that when the output voltage of the temperature detector 111 increases, the output voltage decreases, and when the output voltage of the temperature detector 111 decreases, the output voltage increases, and this output voltage is applied to the reference value setting section 11.
It is designed so that the output voltage does not exceed the output voltage of No. 3. 115 is an A/D converter that converts the output of the analog comparator 114 into digital; 116 is the input of the output of this A/D converter 115; This is an energization time storage unit that stores an energization time value t ₁ and changes the reading when the reference bar rotates once. 117 is the heater bar rotation time measuring section, which measures the time required for one rotation of the reference bar and each other bar based on the timing signal from the timing detector 105, and calculates the reference bar and other bar numbers (No.). A contact closing command is output to the electromagnetic contactor contact 108 at the energization timing of the reference bar, and a command to change the heater energization time value of the reference bar is output to the energization time storage section 116. A correction value for the energization time to the heater is outputted to the calculation unit 118, which will be described later, based on the time for one rotation. This calculation section 118 subtracts the heater energization time value t ₁ and the output value of the heater bar rotation time measurement section 117 from the energization time storage section 116 . Reference numeral 120 denotes a cut heater control circuit configured similarly to the seal heater control circuit described above (specifically, the upper portion surrounded by the two-dot chain line in FIG. 6).

Next, the operation of the temperature control device configured as above will be explained.

[Reference bar control operation]

(1) Based on the signal from the timing detector 105, the heater bar rotation time measurement unit 117 detects the reference heater bar 1 among the heater bars B ₁ to B ₁₀ in FIG.
(The reference heater bar is shown as B ₁ in FIG. 1) and the magnetic contactor contact 108.
Since the closing command is issued, the seal heater
Hs ₁ , only when cutting heater Hc ₁ is energized,
Dummy seal heater for dummy heater bar Db
Hds and dummy cut heater Hdc are also energized. Since the thyristor 106 is conductive, the voltage from the heater power source is applied through the thyristor 106.

(2) In this case, the time width for energizing the sealing heater Hs ₁ and the cutting heater Hc ₁ is for the sealing of the dummy heater bar Dd immediately before energizing the sealing heater Hs ₁ of the reference bar B ₁ and the cutting heater Hc ₁ . Temperature is detected by temperature detectors 111 attached to cut heaters Hds and Hdc, and an output voltage is generated from an amplifier 112 according to the detected temperature, and this output voltage and the reference value of the reference value setting section 113 are analog The comparison is made by the comparator 114, and this deviation value is converted into a digital signal by the A/D converter ₁₁₅ to determine the energization time _t1.The energization time _t1 is determined from FIG.
is proportional to heater temperature _θ1 .

Here, the heater Hsl for sealing and the heater Hcl for cutting are used as dummy heaters for sealing, respectively, because heat is absorbed during actual work.
The temperature is lower than Hds and cut dummy heater Hdc. Therefore, it is necessary to lower the temperature of the dummy heater, and for this purpose, the voltage applied to the dummy heater can be adjusted using the transformer 109.

Here, in order to simplify the explanation, it is assumed that the sealing heater Hs and the cutting heater Hc have the same cooling characteristics. The determined energization time t ₁ is stored in the energization time storage unit 116 according to a command from the heater bar rotation time measuring unit 117, and is updated every time the reference bar B ₁ rotates once.

[Heater temperature control operation other than reference bar]

When each heater is at a constant temperature during the first operation (normal temperature), heater bar B ₂ other than reference bar B ₁
The energization time of ~ _B10 is the same as the value determined in (2) above.

For the second and subsequent rotations, each heater bar B ₁ to _{B 10}
If the time for each rotation is constant, the heater temperatures immediately before the energization timing of each heater bar B ₁ to B ₁₀ are considered to be the same, and the heater energization time value of the reference bar B ₁ and the heater temperature of the heater bars B ₂ to B ₁₀ are considered to be the same. It suffices if the energization time is the same, but in reality, the heater bar may be energized just before the heater is energized due to a temporary stop during the speed change operation of the drive source M, etc.
B ₁ to B ₁₀ seal heater Hs, cut heater
Since the temperature of Hc is not all the same, it is controlled as follows.

That is, in order to set the heater temperature to the optimum temperature θ ₀ for sealing (or cutting) in FIG. 7, heating is performed at different temperatures from θ ₁ to _{θ o depending} on T ₁ to T There must be.

Here, T ₁ : energize the heater of heater bar B ₁ once and
Time until it comes to the re-energization position after rotation T ₂ : energize the heater of heater bar B ₂ once.
Time until it reaches the re-energized position after rotation = Tn: 1 time after energizing the heater of heater bar Bn once
Time to reach the re-energization position after rotation θ ₁ : Temperature increase value to bring the heater temperature of reference bar B ₁ to θ ₀ θ ₂ : Temperature increase value to bring the heater temperature of heater bar B ₂ to θ _0〓 θn: Temperature increase value for setting the heater temperature of heater bar Bn to θ ₀ Regarding heater bars B ₂ to _Bo , since dummy heaters are not provided, the energization time cannot be determined by actually measuring the dummy heater temperature. Therefore, the heaters of heater bars B ₂ to _{B o} have the energization time of the reference bar B ₁ ,
One rotation time and the time required for one rotation of each heater bar B ₂ to _{B o} are measured and calculated to determine the energization time of the heater of each heater bar.

That is, in FIG. 8, (1) seal heater
Create an arithmetic circuit with characteristics that are the same as or similar to the cooling characteristics of Hs. This characteristic is shown in FIG.

(2) Measure the time T ₁ required for one rotation of the reference bar B ₁ (the time from when the heater was energized last time until it starts energizing again; the same applies to other heater bars), and fit it to the curve to determine the temporary energization time td ₁ . Find it and remember it.

(3) The heater energization time of the heater bar _B2 is as follows: (a) Measure the time _T2 required for one revolution of the heater bar _B2 , and calculate _td2 from the heater cooling characteristics.

(b) Find Δt ₂ using (td ₁ − td ₂ ).

The value obtained from the above is (t ₁ −Δt ₂ ).

Here, t ₁ : Time to energize the heater to raise the temperature of the reference bar B ₁ to the heater temperature θ ₁ , t ₂ : Time to energize the heater to raise the temperature to the heater temperature θ ₂ of the heater B ₂ 〓 tn: Heater energization time to raise the temperature of heater bar Bn to heater temperature θn td ₁ : Heater energization time based on the heater cooling characteristics of heater bar (reference bar) B ₁ td ₂ : Heater cooling characteristics of heater bar B ₂ Heater energization time for above = tdn: Heater energization time for heater bar Bn heater cooling characteristics (4) For heater bars Bn other than heater bar B ₂ , use the same method as above to calculate Δtn from (td ₁ − tdn). The required heater energization time is (t ₁ −Δtn).

(5) When heater bar B ₁ rotates once, t ₁ and td ₁ are canceled, the temperature of the dummy heater is actually measured, and a new
The values of t ₁ ′ and td ₁ ′ are determined, and at t ₁ ′, the heater of heater bar B ₁ is energized. At the same time, T ₁ ' from the previous energization point to the current energization position is determined, and the heater energization time of heater bars B ₂ to _{B o} is determined in the same way as in (3) above.

According to the embodiment of the present invention described above, since the heater energization time width is automatically controlled, it is possible to prevent melting or poor adhesion of the seal portion of the plastic sheet, and since the heater does not generate red heat, the life of the heater is extended. According to the above, it is possible to provide an impulse heater temperature control device that can automatically obtain an optimum heater temperature when the heater is pulse-energized without using a forced water cooling method or a forced air cooling method.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a schematic configuration of an impulse sealing machine, Fig. 2 is a perspective view of an item packaged by the impulse sealing machine of Fig. 1, and Figs. 3 and 4 are a diagram showing the heater bar of Fig. 1. FIG. 5 is a perspective view showing a schematic configuration of the dummy heater bar in FIG. 1, and FIG. 6 is an implementation of the impulse heater temperature control device according to the present invention. A block diagram showing an example, Fig. 7 is a characteristic diagram showing the heater cooling characteristics and the required heater energization time of the same example, and Fig. 8 shows the elapsed time after heater overheating and the necessary heater energization time correction value of the same example. It is a characteristic diagram. 101...Motor, 102...Reducer, 103
...Seal heater Hs and cut heater Hc
104... timing cam, 105... timing detector, 106... thyristor, 107... heater energization control unit, 108
...Magnetic contactor contact, 109...Transformer, Dd...
...Dummy heater bar with heater Hds for dummy seal and heater Hdc for dummy cut, 110
...Dummy heater, 111 ...Temperature detector, 11
2...Amplifier, 113...Reference value setting section, 114
...Analog comparator, 115...A/D converter,
116... Energization time storage section, 117... Heater bar rotation time measurement section, 118... Calculation section.

Claims (1)

[Claims for Utility Model Registration] A sealing heating device that has an electric heater and heats a sealing material of a packaged object by passing current intermittently to the electric heater, the thermal time constant being approximately the same as that of the electric heater. a dummy heater; a temperature detector for detecting the temperature of the dummy heater; switching means for energizing or de-energizing the electric heater and the dummy heater; An impulse heater temperature control device including a computing unit that determines the amount of electricity applied to the impulse heater.