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基于IGBT 多電源模塊的創新加熱技術
 1. 簡述
現代生產對鍛造工藝不斷提出新的技術要求：高產能，高精度以及高度的靈活性。這迫使人們以新的策略和思維來滿足技術要求。
加熱工藝的優劣以及重復精度對鍛壓成形工藝有重要影響。首先，必須確保坯料具有成形所需的合理熱焓值。其次，軸/徑向溫度分布均勻。但是這與氧化皮與粘接問題降低的要求相矛盾。另外一個引起高度重視的是與日益上升的能耗成本背景相關的節能問題。再有，加熱系統的長度也受到廠房的空間約束。因此，根據客戶要求以及適應加熱工藝是獲取高可靠性和高效率的關鍵。
2. 模塊化加熱系統的概念 加熱效果與加熱線的總長度，線圈的數量和功率，以及頻率都有重要關系。對于單一電源加熱的加熱系統，只能實現對某一特定規格，特定產量條件下的坯料加熱單獨設計與之相適應的最優化溫度分布，最小氧化皮以及最低的粘接率和能耗。這可以通過選擇合適的線圈匝數以及工作頻率（單一電源，單一頻率）來實現，由于頻率單一，無法采用最優化的頻率加熱不同加熱工藝階段的坯料。比如對于坯料最初預熱階段，此時坯料還處于鐵磁體狀態，比較適合采用低頻率加熱以便不僅僅加熱坯料的表層，同時也深入加熱坯料內部。在加熱的中間階段，坯料表面溫度介于居里溫度和所需的鍛造溫度之間，此時適合采用比預熱階段高的頻率加熱以降低能耗。在最后階段，主要目的是彌補表面與中心溫度之間的溫差以獲得理想的軸/徑向溫度分布。這時需要最高的工作頻率以補償表面散熱。采用獨立控制，以不同頻率向各個線圈獨立供電的新技術后，盡管各個階段所需功率不同，我們仍能采用匝數相仿的線圈。這樣，同一線圈可以用于任何加熱階段，從而有效減少備用線圈數量要求。
ABP多電源概念基于IGBT變頻電源技術。在模塊化變頻電源中，每個IGBT單元是一個250KW的變頻電源裝置。
各個模塊可以根據加熱工藝要求自由組合以便每個線圈獲得所需的功率。通常情況下，每個線圈可以由最多3個模組的IGBT向該加熱區間提供所需功率。在其后的加熱區間一般要求較低的功率，因此所用的IGBT模組也較少。加熱最后階段的保溫由單個250KW的IGBT模塊。設計思路是每個加熱階段的加熱能力獨立于線圈設計。各模組由連接主板整合，從而獲得加熱工藝所需的功率大小。功率控制由IGBT 控制板完成，帶獨立CPU，光纖連接。此項技術具有很好的穩定性并已經在世界范圍內的客戶得到廣泛的應用。
3. THERMPROF©加熱工藝控制軟件包 由于可以單獨控制每個線圈的供電，用戶需要一個有力的工具，借助這個工具可以毫不費力地根據自己的生產要求，使鍛溫度分布均勻，低能耗，少粘接與氧化皮問題，避免過熱現象和坯料熔化現象，從而獲得最佳的加熱效果。
THERMPROF©正是適應這樣要求而開發的工具。這是一款針對熱焓控制加熱系統中多電源技術加熱工藝的預先計算客戶軟件包。客戶可以輸入所需加熱坯料的直徑，長度大小和所需產量，生產節奏。
同時定義坯料離開每個線圈時的截面平均溫度（熱焓值），從而獲得坯料中心，表面，平均溫度圖表以及氧化皮情況。用戶可以自行定義每個線圈允許的最高區域溫度，監控變頻電源的負荷值與溫度從而避免過載或坯料的局部熔化。如果其中某個變頻電源出現故障，在THERMPROF©中可以關閉該區間并計算出剩余部分可能達到的最高產量。
欲了解溫度的詳細信息，可以打開另一個窗口，它可以三維圖示坯料內的溫度分布情況。并且可以顯示坯料在加熱移動過程任一點位置的溫度分布情況。通過確定從坯料離開加熱系統到鍛壓成形中間的時間間隔，可以通過相似的方法監控這期間冷卻前后的坯料溫度分布。因而，用戶可以對坯料從加熱開始到成形過程至始至終的完整監控。
THERMPROF©另外一個特征是成本分析功能。它充分考慮能耗，材料成本，氧化皮損耗，以及由于溫度分布問題在成形過程中可能對鍛模造成的磨損。這樣，利用THERMPROF©用戶可以借助成本分析工具修改加熱工藝從而優化單件成本。
另一個多電源變頻技術模塊化熱焓控制加熱系統的優點在于任意產量和坯料規格條件下平滑的坯料截面平均溫度加熱曲線。有效避免在產量低的條件下的過熱現象，同時在產量變化時加熱系統加熱的坯料溫度波動小。
4.加熱變頻控制系統 PRODAPT®-FX是專門針對鍛造車間使用環境的加熱程序處理系統。它能有效幫助工作人員為每種坯料尋找最理想的設定參數并且貯存參數供反復調用。其硬件基于工業應用的AC800 軟PLC，無旋轉部件。該處理系統可以從THERMPROF軟件包獲取參數后獨立運行相關功能。這是一款在其它工業領域廣泛使用的成熟技術。
用戶友好的可視操作界面面板適合鍛造工廠環境。在面板上操作人員無需鼠標通過觸模面板和功能鍵進行操作。控制器本身無易損壞件，防震設計。
在控制面板上顯示工藝過程，因此用戶可以全過程監控工藝過程。同時還可以在生產過程中修改相關參數。一旦鍛造生產線上游或下游設備出現故障，立即將功率輸入調整到最小值以降低廢料量（保溫功能）冷啟動功能用于減少開機過程可能產生的廢料。在冷態線圈條件下，調低功率輸入以達到較好的預熱過程。“循環操作”用于向坯料提取機構準確經過加熱的坯料，循環控制根據循環時間設定精確控制。
英文版如下:
Innovative heating concept using IGBT multi-converter technology
1. Introduction
The technological requirements for the forging process are forced by the needs of a modern production cycle. So high productivity, accuracy in quality and very high flexibility of different parts force the production process to come up with new strategies and ideas to recover the different technical needs.
The whole forming process is strongly influenced by the quality and repeatability of the heating process. So the first target is to obtain the desired enthalpy content in the billets. Furthermore the axial and radial temperature differences in the billets should be as small as possible. However this conflicts with a low scaling and sticking rate. Another important aspect under the view of increasing energy costs is an energy consumption optimized production. Furthermore the length of the equipment is limited by the space of the production facility. So it is very important that the heater respectively the heating process is well adapted to the customers’ requirements in order to get reliable production and high productivity.
2. The concept of a modular heater system
The quality of the heating process strongly depends on the total length of the installation, the number and power rates of the coils as well as their frequencies. For a single converter installation the coils can only be optimized for a single throughput and billet dimensions with respect to small temperature differences in the billet with a low scaling and sticking rate and at low energy consumption. This optimum results from the right choice of the winding number for each coil and the operation frequency
which must the same for all coils, since they are fed only by a single converter. So this frequency also can only be a compromise. At the heater inlet, where the billets are still cold and therefore ferromagnetic, a low frequency is appropriate to heat up not only the billet surface but also its inside.
For the centre section of the heater where the surface temperature of the billets is approximately between curie temperature and the desired forging temperature a higher frequency is necessary to keep the energy consumption small. In the last section basically a temperature compensation between the surface and the centre should be effected to get a homogeneous axial and radial temperature distribution within the billets. The highest frequency is necessary in order to compensate the thermal losses on the billet surface in essence. Due to that new technology with separately fed coils at different frequencies by separately controlled converter units it is possible to make the winding numbers of all coils mostly equal in spite of different required power rates for the respective heater sections. Therefore every coil can be placed at any position so that the number of required spare coils can be reduced substantially.
This multi converter concept is based on IGBT converter technology. Therefore modular converters are designed in such a way, that every IGBT unit is a single converter of 250kW.
The modules can be combined in such a way that each coil gets the necessary power for the specially designed heating process. Mostly a combination of maximum 3 modules per heating region is combined to supply the power to that coil for the heating region. The heating task leads to a reduction of the needed power in the following regions so that there an installation of fewer modules is required.
In the end of the heater the holding zone is fed with 250kW or in fact with one converter for the power supply. The principle is designed to scale the heating process in the different regions independently from the coil design.
The modules are integrated in the converter board. Therefore a combination of the single modules to the power supply is adapted to the overall heating process.
The power control is realized with an IGBT control board with an own CPU via fibre cable connectors.
That system is very reliable and well proofed in different heating installations world wide.
3. THERMPROF© – a software package for controlling the heating process
Since it is possible to control separately every single coil respectively every single converter unit the user needs a tool to find out how to do this to avoid overheating or melting of the billets and to get the best heating process as possible for his special task without any time and cost intensive attempts for an optimal heated billet with respect to uniformity of temperature, low energy consumption and low sticking and scaling rate.
For that task THERMPROF© has been created. It is an end user software package designed for the pre-calculation of the heating process of multi-converter technology heaters for an enthalpy controlled zone heating. The user can quote the desired billet diameter and the throughput or the billet length and its cycle time. Furthermore the averaged temperatures (enthalpy) of the billet cross section area at the ends of every separately controlled coil or coil unit must be defined. The result is a chart for the core, surface and averaged temperature of the billets and the scaling within the heater.
Converter load and temperature are supervised in order to avoid converter overload or local overheating of the billets where the admissible maximum local temperature for each separately controlled coil or coil unit section can be defined by the user. If a converter unit fails this unit can be switched off in THERMPROF© to find out the highest throughput which is still possible.
For more details about the temperature another window can be opened where the temperature distribution within the billet is shown in a coloured 3D visualization. That can be done for any position of the billet by moving the billet along the heaters length. Since it is possible to define the time from leaving the heater to the first forming the temperature within the billet during and after that cooling down time can also be monitored in that way. So the user has the total control about the billet temperature from the beginning of the heating process up to the first forming.
Another feature of THERMPROF© is the cost calculator. It considers the energy consumption, the material costs with respect to the scale losses and the die wear against the uniformity of the temperature distribution within the billets at the first forming. Now with THERMPROF© the user is able to modify the heating process in order to optimize it respectively to minimise the piece costs with the help of the cost calculator.
A further advantage of the enthalpy controlled zone heating by IGBT multi-converter technology is an
even heating up curve of the averaged temperatures of the billet cross section area independent of throughput and billet dimensions. This avoids overheating within the heater at low throughputs and leads only to small billet temperature fluctuations at the heater outlet after throughput changes.
3. PRODAPT-FX - Heating processor for converter control system
The heater processor PRODAPT®-FX is designed for the use in the environment of a forging shop. It helps the blacksmith to find the optimum setting values for the heater for the respective billet programs and to store the values once they have been found, so that they can be reproduced any time.
The hardware is based on the industry controller AC800 soft PLC without any rotating parts. The processor is able to take over the parameters from the software package THERMPROF and to control all the necessary functions out of that information. It has proved its value many times over in other industrial sectors.
Operation and visualization are performed by an operator panel which is user-friendly and suitable for the forge environment. By means of the panel, the heater can be operated via a touch screen and function keys without a mouse. The controller itself has no vulnerable hard disk or active ventilation system and is insensitive to vibrations.
The control during the process is visualized on the control panel. So the user can follow the process all the time and the process can be controlled in a very short time. Also changing of parameters can be done online during the process is in operation in different steps.
In the events of faults in upstream or downstream installations of the forging line, the feed is slowed down to the minimum possible value to reduce the scrap (Holding function). To reduce the scrap when starting up the installation the “Cold Start-up Function” is used. If the coil lining is still cold, the feed is initially reduced to ensure heat-soaking of the coil lining.
The “Cycle Operation” is used to supply the heated billets to the extraction unit with accurate cycle-timing. The feed is controlled in such a way that there are no undefined cycle times if changes are made to the cycle time. |