Japanese English

Aluminum extrusion press

Constant velocity extrusion / isothermal extrusion

Control system

RcdWin

RCDIGITAL,Inc.
November  2022

Latest information on 20181204 version program You can download constant velocity extrusion (RcdWin) brochure. (Japanese)
(Right-click-> Save to file, you can download it.)
The latest information on the 20181205 version program You can download the isothermal extrusion (RcdWin) brochure. (Japanese)
(Right-click-> Save to file, you can download it.)

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1 High speed extrusion

1-1High speed extrusion

If the control voltage is feed back so that the error between ram speed and setting speed is zero, constant speed control can be realized. Here, the control voltage determined from the characteristics of the extruder is added as a feedforward to the voltage determined from the feedback. This makes the ram speed rise faster. This feedforward control voltage can be used as a responsive control voltage for overshoot.


With the automatic adjustment of the ram speed rise adjustment of Chapter 19, the rise is made even faster. Optimization by automatic adjustment of ram speed rise

Examples of high-speed extrusion are shown in Figures 1-2 to 1-4.

1-2 Characteristics of extruder

The properties of the extruder referred to here are the relationship between the ram speed and the control voltage in the steady state of extrusion (the state where the ram speed maintains the set speed). This can be expressed by a linear equation. By effectively utilizing this relationship, the rise can be made faster and overshoot can be reduced.

The problem is that this relationship changes. Dynamically correct the equation for small changes (eg seasonal, equipment related hydraulic anomalies etc). However, if phenomena such as overshoot or noticeable rise occur, it is possible to change the equation with a simple operation. Usually, there is no problem if the calculation of equations is made automatic. RcdWin has a function to calculate relational expressions from the latest data and display as shown in Figure 1-1.




Figure 1-1 Graph of extruder characteristics Press Machine


Fig. 1-2 With feed forward The set speed is 6.2 mm / sec. It is an extrusion die that is difficult to rise.


Fig. 1-2 With feed forward The set speed is 6.2 mm / sec. It is an extrusion die that is difficult to rise.


Fig. 1-2 With feed forward The set speed is 6.2 mm / sec. It is an extrusion die that is difficult to rise.

1-3Control theory


1-3-1Ram-torque(flow rate) relation

In the steady state, the ram speed and the output torque are in the linear relationship as shown in Figure 1-1. The control torque (flow rate) is predicted and calculated using that relation. Therefore, stable constant-speed control can be performed from low speed to high speed.





1-3-2Feedback + feed forward

According to the following equation, feedback by PID and feedforward by relational equation are simultaneously executed. Therefore, stable high-speed extrusion is possible.

Torque (flow rate) = Kp x e + Ki ∫ edt + Kd de / dt + f (ref)

here, Torque (flow rate): Control voltage (torque) Kp: proportional gain Ki: Integral gain Kd: differential gain e: Deviation f (): Ram-torque relation ref: setting voltage




1-3-32 degrees of freedom PID

The parameter of PID can be set by separating start-up mode and constant speed mode.
Therefore, even if you decrease the control gain to suppress the overshoot of the rising edge, it does not affect the constant speed control.




1-3-4Pressure consideration

Even if the ram speed reaches the set speed, it can not be said steady when the main pressure of the press is suppressed by the relief valve set value. Therefore, the rise mode and the constant velocity mode are judged in consideration of pressure.

When the relief valve is blowing, the load on the hydraulic motor is reduced by suppressing the torque signal.

The hydraulic pump stops when the relief valve blows and high pressure continues for a long time.

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2 Overshoot prevention

Since the feedback gain at ram speed startup and the feedback gain at constant speed are separated, adjustment for overshoot prevention can be performed independently of the constant speed part.

Also, in feedforward, control signals are calculated to prevent overshoot and prevent hunting, taking into consideration ram speed gradients, errors and extruder characteristics.

The left side is RcdWin constant velocity extrusion, and the right side is PID constant velocity extrusion. RcdWin does not overshoot, but PID overshoots a lot.


The left side is RcdWin constant velocity extrusion, and the right side is PID constant velocity extrusion. RcdWin does not overshoot, but PID overshoots a lot.

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3 Energy Conservation

Even if the control voltage is increased more than necessary as the ram speed increases, the flow rate becomes invalid, leading to oil temperature rise and power loss. To prevent this, the relationship between ram speed and pressure prevents the control voltage from becoming unnecessarily large. If the overload condition continues for a long time, the hydraulic pump will stop.

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4 Pressure limit

Control so that the pressure of the press does not exceed the pressure limit value as much as possible. This value can be set interactively from the computer keyboard.

The following purposes are effective.

Fig. 4-1 Example of pressure limit and inclined extrusion. The set speed is 2.2 mm / sec.



Explanation> The torque (flow rate) is reduced because the pressure exceeds the relief valve value. In the second half, the ram speed is ramped so that the product temperature does not rise and become defective.

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5 Ram speed inclined extrusion

In the second half of the billet, depending on the material, the speed is inclined. This is to prevent the temperature of the product from rising. RcdWin can set a slope pattern as shown in Figure 5-1.

Figure 5-1 Pattern of Inclined Extrusion


Fig. 5-2 Inclined extrusion parameter input screen


Fig. 5-3 Inclined extrusion setting speed is 6.1 mm / sec, final speed is 5 mm / sec.


Fig. 5-4 Inclined extrusion setting speed is 9.7 mm / sec final speed 5.4 mm / sec.

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６ Control screen

When controlling with RcdWin, the display will show the screen as shown below.
The display in the center of the graph shows the extrusion control status.
The display of numerical values etc. outside the graphs is the display of measurement data and control parameters when extrusion is finished.


Figure 8-1 RcdWin Control Screen

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７ Extrusion data search

RcdWinMoni searches by date and time, and displays 20,000 extrusion data registered by rcdWin.



図9-1 RcdWinMoniの制御画面

RcdWinMoni searches by date and time, and displays 20,000 extrusion data registered by rcdWin.
Spectrum analysis of ram speed data

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８ Remote maintenance

Install programs, adjust control parameters, and maintain programs using the Internet. Remote support (click here).

Figure 10-1 Explained> Remote maintenance in three countries using TeamViewer

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９ PC screen

Figure 11-1 Constant velocity extrusion (RcdWin) and extrusion management (EM)

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１０ Distributed control of PC and network PLC

 

PC control of the aluminum extruder can now be decentralized using a PC connected to the LAN and a network PLC.
The role of the PC is to execute the extruder control logic. The role of the network PLC is to exchange signals with the equipment.

The advantages of PCs with distributed control are as follows

The merits of PLC by distributed control are as follows.

The PC will be able to concentrate on work in areas such as computing and databases. Although PLCs are mainly for exchanging signals with equipment, it is also possible to incorporate simple control logic.

Note> Network PLC: PLC with Ethernet function (Programmable Logic Controller). A small computer in the palm of a hand developed as an alternative to relay circuits. Used for sequence control of factory automated machines.

15-1 Distributed control diagram of personal computer and network PLC

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１１ Real-time monitor of aluminum extrusion

 

We made a real-time monitor as one screen of extrusion data analysis (EDA). Instead of displaying extrusions one by one, multiple extrusions are displayed continuously.
Unlike RcdWind, EDA can be installed on multiple PCs. EDA can also view the history of what kind of speed previously extruded on the extrusion die unit. It is a useful tool for workers.

Figure 17-1 Partial screen of extrusion data analysis (EDA). It can be installed on multiple computers.

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１２ Spectrum analysis of ram speed data

 

The spectrum analysis was performed on the CSV file of constant velocity extrusion 12.7 [mm / s] and constant velocity extrusion 1.9 [mm / s] output by RcdWinMoni program. It was found that the slower the ram speed, the faster the vibration cycle and the larger the amplitude.

When the ram speed is fast, it vibrates at ± 0.10 [mm / s], and the cycle is about 1 second.
When the ram speed is slow, it vibrates at ± 0.15 [mm / s], and the cycle is about 0.5 seconds.

Conducting analysis regularly helps maintain the machine.
It is useful as analysis data when a defect occurs.

The spectrum analysis of ram speed data of another factory is shown in 18-3. You can see that the ram speed data differs depending on the machine.

18-1 Spectral analysis of constant velocity extrusion 12.7 [mm / s]

Figure 18-1 There are three peaks in the spectrum. The ram speed is vibration (± 0.105 [mm / s]) at 4.39 [V]-4.32 [V] = 0.07 [V] ± 0.035 [V] and the vibration cycle is about It is one second.

18-2 Spectrum analysis of constant velocity extrusion 1.9 [mm / s]

Fig. 18-2 There are three peaks in the spectrum. The ram speed vibrates at 0.83 [V]-0.73 [V] = 0.1 [V] ± 0.05 at vibration (± 0.15 [mm / s]) The cycle is about 0.5 seconds

18-3 Spectrum analysis of constant velocity 1.9 [mm / s] at another factory

Figure 18-4 There is no mountain in the spectrum. The ram speed vibrates at 1.16 [V] -1.19 [V] = 0.03 [V] ± 0.015 (± 0.045 [mm / s])

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１３ Optimization by automatic adjustment of ram speed rise

 

The main goal of constant velocity extrusion is to start as quickly as possible without overshooting. There are start-up factor and start-up time for parameters. Optimized them.

19-1 Automatic adjustment when overshooting

図19-1 説明＞設定速度５.9[mm/sec]　立上係数１．０でオーバーシュートしました。そのため、係数が０．９になりました。

Fig. 19-2 Description: Setting speed 5.9 [mm / sec] Extrusion with extrusion coefficient of 0.9, there is no problem, so the coefficient remains at 0.9.

19-2 Automatic adjustment when the rise is late

Fig. 19-3 Speed setting 9.7 [mm / sec] The extrusion was performed with a rising coefficient of 1.0, and the coefficient became 1.1 because it did not become uniform in 9 seconds.

Fig. 19-4 Set speed 9.7 [mm / sec] Extrusion with extrusion coefficient 1.1, there is no problem so the coefficient remains 1.1.

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１４ Automation of ram speed rise time

 

In “19. Optimization by automatic adjustment on ram speed”, we explained the rise factor. Here we will explain the start-up time.

20-1 Operation of start-up time automation

The start-up factor automation is faster for extrusion dies that start later than the start-up time. However, for extrusion dies that start earlier than the start-up time, start up later. Use launch time automation to ameliorate this disadvantage. If the rise factor does not change, do not overshoot and shorten the rise time. Conversely, if it is overshooting, make it longer. If the number of times the rising coefficient does not change is set to 2 times, the rising time changes from the third time.

20-2 Calculation of Effects of Start-up Time Reduction

Description> The shortening of extrusion time by shortening the rise time is the area of a parallelogram.

is assumed that the rising coefficient and the rising time are as follows.
If you want the rise time to be 10 seconds to 5 seconds.

Start-up factor 0.5 seconds
Start-up time 10 seconds

Start-up factor 0.5 seconds
Start-up time 5 seconds
When the ram speed setting is 6 [mm / s], the extrusion time is area of ​​speed × time, so calculate the area of ​​the parallelogram and divide by two.
The setting speed 6 [mm / s] is divided by 2 because the rise factor is 0.5. The difference in the start-up time is 5 "s", so multiply by 5.

(6 [mm / s] / 2 * 5 [s]) * 0.5 = 7.5 [s]

7.5 seconds extrusion time is reduced.
The effect of shortening the rise time is proportional to the ram speed setting.

In the case of 4 [mm / s], it is 5 seconds earlier.
When it is 10 [mm / s], it will be 12.5 seconds earlier.

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１５ Constant velocity extrusion of circular pipe 2 holes

It was told by the extrusion worker that extrusion of the circular pipe 2 hole was difficult. Constant velocity extrusion was achieved without problems by the method of pressure restriction that has been proven for over 20 years at a factory that produces industrial extruded materials in Japan. Extrusion workers were also delighted with the fact that constant velocity extrusion made the work easier. Because it was said that [set to machine] was troublesome in setting of extrusion speed, it was made to change speed immediately with [+0.1] button etc. Again, the extrusion workers were delighted.

Fig. 21-1 Description: Automatic setting of extrusion speed for constant velocity extrusion of 2 round pipe

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１６ Low speed constant velocity extrusion

 

Industrial extrusion materials often have low-speed extrusion of around 1 [mm / s]. In this example, the pressure does not exceed 210 [kg / cm2]. Some high-pressure dies last 210 [kg / cm2] for a long time.
The constant velocity extrusion setting is 1.5 [mm / s], but for manual extrusion it seems to be around 1.2 [mm / s]. In the case of manual operation, it increases by 0.3 to 0.4 [mm / s] in the second half.
In this example, the extrusion time is 386 seconds, but there are many more than 500 seconds. Set the constant velocity extrusion speed about 0.4 [mm / s] faster than manual extrusion. In that case, 0.4 * 500 = 200 seconds extrusion time is shortened.

The start-up factor is automatically adjusted. The torque (flow rate) is increased, but this is to raise the ram speed faster.

The ram speed sensor is a position sensor. Figure 19-1 is a speed sensor. It can be seen that when the constant velocity extrusion is performed by the position sensor, the puller speed tends to be inclined.
One of the causes of product failure is because the temperature rises in the second half. If the puller speed is inclined, it can prevent the temperature rise in the second half.
Constant velocity extrusion with a position sensor is difficult. Other companies do not do. However, the advantage of temperature rise prevention may be fortunate (It was hard, but there is an advantage) in the Japanese language.

The PID parameters were divided into two parts, high speed extrusion and low speed extrusion. It seems that they are quite different, so I think that 2 divisions were good. Adjustment is also easier.

Fig. 22-1 Description: 1.5 mm / s constant velocity extrusion with position sensor

Fig. 22-2 Description> PID parameter input screen divided into 2

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１７ Multilingual support of RcdWin control parameters

 

You can select a language in the Language list box. Currently, I have created language resource files for English, Japanese, Korean, and Chinese. We will also create resole files for other languages. As it is only translated by Google, it is not that much trouble.

The parameter of this Environment screen was also newly created. It can be displayed in Environment-> Environment1 of the menu bar.

Figure 23-1 Explanation> Environment Data Screen in English

Figure 23-2 explanation> Environment Data screen in Japanese

Explanation of Figure 23-3> Environment Data Screen in Chinese

Explanation of Figure 23-4> Korean Environment Data Screen

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１８ Interface PLC interface data and PLC parameter data input screen

 

We created the Plc Interface Data screen to make it easy to exchange data with equipment machines.
RcdWin exchanges data with PLC to perform constant velocity extrusion. In the example in Figure 24-1, use PLC devices D100 to D126. Adjust the scale of the data here.
RC Digital installs the program on your computer remotely or by going to the factory. However, data from 1 to 12 must be prepared at the factory. As 13 to 16 are the output of RcdWin, it is necessary to connect this to the machine of the equipment. This also has to be done by the factory. If it is difficult at the factory, it is better to ask a specialized equipment remodeling company.
The minimum data required for constant velocity extrusion is only 1, 2, 5, 6, 7, 11, 13, and 16.

I wrote the factory LAN wiring in Figure 24-3. Rc Digital remotely installs a program and adjusts program parameters. A factory or a specialized equipment remodeling company prepares a personal computer and an Interface PLC. Then connect the Interface PLC and the machine's PLC, and check the data transmission / reception. Please contact us by email for details on how to modify the equipment.
The program can be maintained remotely. However, machine maintenance and electrical work can not be done remotely. If you use a specialized equipment remodeling company, I think it is better to select a company near the factory. Figure 24-2 shows the screen for setting PLC data. Manufacturer's model of PLC, IP address and port etc. The PLC model is Mitsubishi's Q03UDE CPU. Mitsubishi, Omron and Siemens have proven results. Please contact us for other PLCs.

Figure 24-1 explanation> Interface data with PLC

Explanation of Fig.24-2> PLC data

Figure 24-3 explanation> Remote maintenance PC and RcdWin PC and interface PLC and multiple PLCs of factory machine

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