5 Reka Bentuk Kren Kilang Kertas untuk Susun Atur Bengkel Industri Kertas yang Mudah

According to years of experience in crane manufacturing maintenance and transformation, through the analysis and comparison of various layouts and types of cranes in the paper mill workshop, put forward a reasonable selection and optimal layout scheme. Preparation or technical transformation of new and old projects in paper mills, paper mill crane design or maintenance and transformation are of high reference value.

The importance of reasonable selection of cranes and optimal layout

In the paper mill workshop, the crane is an indispensable link in the papermaking process, mainly used for paper machine equipment lifting and installation, the work is quite busy. Due to the special process of papermaking, the paper workshop environment is harsh (high temperature, high humidity, air with paper dust) and crane use level and frequency of use and so on, so the paper mill crane and general bridge cranes have obvious characteristics. Therefore, the reasonable selection and layout of the crane can not only reduce the initial crane investment and plant construction costs but also reduce the crane operating costs and maintenance costs, reduce the loss of paper machine downtime, improve corporate efficiency and enhance the competitive advantage of enterprises.

The form and layout of the past paper mill crane

Previously, most paper mills paper workshops design layout of 3 cranes, cranes using electric double girder bridge structure, lifting mechanism using winch form. Among them, the wet part of the paper machine has a 3-trolley double girder bridge crane (hereinafter referred to as double girder bridge), mainly used for the maintenance of the paper machine (referred to as ‘service cranes’); paper machine cadres have two sets of the same double trolley double girder bridge, mainly used for lifting paper rolls (referred to as ‘paper roll crane ‘), 1 for the daily work, the other 1 for the backup, in order to avoid crane failure caused by the paper machine downtime, see Figure 1. 3 cranes are not fully utilised, of which 1 is basically idle, long-term use is more prone to failure, not only greatly increase the cost of investment, but also greatly increase the cost of equipment management, maintenance, spare parts and so on.

Because most of the paper mill crane working level requirements are higher, the whole machine A6, the agency M6, while the previous ordinary electric hoist working level is low (most <M5), the lifting capacity of the electric hoist either product immaturity, high failure rate, or working level is even lower (usually M3, M4), simply can not meet the requirements of the working conditions of the paper machine shop. Therefore, the past paper machine line cranes, the vast majority of the general bridge crane based on the design, that is, the hoisting mechanism using the winch structure, the size of the car running mechanism using a motor, reducer, brake independent transmission structure, this crane is not only self-importance, wheel pressure, size, resulting in track beams, columns and height of the plant and other infrastructure costs, and the whole machine power, low reliability This crane not only has a large self-importance, large wheel pressure, large size, resulting in increased infrastructure costs such as track beams, columns and plant height, but also has a large electrical power and low reliability of the whole machine, resulting in increased operating and maintenance costs. It can be seen that the past form of crane and layout has not been able to adapt to the modern paper industry management and production requirements, should be technological reform and innovation.

Modern paper mill crane form and layout

Through detailed technical analysis, rational design and selection of high-quality components, you can use 2 (or even as little as 1) electric hoist double girder bridge instead of the previous 3 electric universal bridge. In this way, the number of cranes can be reduced by 1/3, but also due to the crane wheel pressure reduction, height reduction, corresponding to reduce the track beam cross-section, column cross-section, track specifications, reduce the height of plant construction, saving the total investment of about 35%. Energy saving and power saving due to the reduction of crane power. Such a design and layout, used in many paper lines, 7 years of accumulated experience, with obvious economic benefits. The following analysis compares the advantages and disadvantages of various crane layouts and types.

Paper mill crane programme 1

Each paper workshop set up 2 sets of the same bridge, 1 is the paper machine dry end of the paper roll crane, 1 is the paper machine wet end of the service crane (according to the actual situation of the paper machine and so on, and even can only set up a crane). There are 3 trolleys on the crane bridge. The outer 2 trolleys are used for lifting paper rolls, empty paper rolls and other purposes; the middle trolley is used for the replacement of various rolls and cylinders of the paper machine and other maintenance services, and can also be used as a backup trolley for lifting paper rolls in case of failure of any of the outer trolleys. For this purpose, the lifting speed of the 3 trolleys is the same as the running speed of the trolleys.

Generally the lifting mechanism of the outer 2 trolleys has a working class of at least M6 (FEM 3m) and the centre trolley is mainly used for maintenance services, compared to the outer trolleys. It can have a lower working level, e.g. M4 (FEM 1 Am), but with a higher lifting capacity, usually twice as high as the outer one. For example: 20 t/M6 + 40 t/M4 + 20 t/M6. In this way, the centre trolley is able to lift the cylinder alone, with the following parameters.

The greatest benefits of this form of crane construction are versatility and reliability. The paper roll crane can also be used for service or as a back-up for the service crane. The high reliability is due to the fact that a failure of any of the trolleys will not affect the production process.

If a workshop layout of 2 such cranes, the reliability is very high, downtime loss is almost 0. If only a layout of 1 crane, the advantage is the minimum investment, but also to meet the daily production requirements for use, the disadvantage is that the large trolley operating mechanism failure will affect production, should strengthen the crane’s routine maintenance work.

Paper mill crane programme 2

Is a variant of programme 1, crane bridge only 2 trolleys, of which 1 trolley only 1 hoisting mechanism, another trolley has 2 hoisting mechanism, the main hook form. The hoisting mechanism with a large lifting capacity is arranged in the middle, e.g. 20 t+40/20 t. Similarly, the 20 t working class is M6 and the 40 t working class is M4. Other similarities are found in scheme 1.

The advantage of this construction programme is that the trolley is compact, simplify the electronic control control, save steel structure and electronic control materials, reduce crane manufacturing costs. The main disadvantage is that the traverse speed is not synchronised due to the different loads of the 2 trolley running mechanisms, and certain measures need to be taken.

Paper mill crane programme 3

Each paper workshop set up 2 different bridge, paper machine wet end of the arrangement of a 3-trolley service crane, paper machine dry end of the arrangement of a double-trolley paper roll crane. Paper roll crane work is relatively busy, paper roll + lifting beam weight close to the rated lifting capacity of the crane, its working level at least M6, such as: 20 t/M6 + 20 t/M6. Service crane can be the same as the design of the programme 1, such as: 20 t/M6 +40 t/M4 +20 t/M6, the outside of the 2 trolleys as a back-up for the paper roll crane, the lifting speed of the 40t hook can be designed with the same speed as the 20t hook or the same speed as the 20t hook. The lifting speed of the 40t hook can be designed to be the same or different from that of the 20t hook. If the speeds are different, the 40t hook cannot be used to replace the 20t hook for lifting paper rolls.

As the wet-end service crane is usually used less, in order to further save crane manufacturing costs, according to the actual working conditions, the service crane’s whole machine and the outer trolley’s working level can be designed to be one level lower than that of the cadre’s cranes, e.g. M5 (FEM 2m).

This layout paper roll crane with double trolleys is more economical compared to Option 1, and peripheral trolley failures do not affect production essentially. The same as programme 1, the disadvantage is that the wet part of the crane is usually low usage, if the paper machine is parked for a long time above the wet end of the crane, high temperature, humidity and paper debris, etc. on the steel structure of the crane and the electrical control system corrosion is greater, should try to park the crane away from the humid place.

Paper mill crane programme 4

Each paper workshop set up 2 different bridge machine, paper machine wet end arrangement of a service crane, paper machine dry end arrangement of a single trolley crane.

The paper roll crane is 2 hooks from two lifting points of the same trolley with the following parameters. This structure is suitable for small lifting capacity and narrow width of the paper machine. The biggest advantage of this type of crane is that the 2 hooks are mechanically synchronised, but the distance between the 2 hooks varies slightly with the lifting height. The advantage is to reduce the number of trolleys, substantial cost savings. The disadvantage is that when the trolley running mechanism fails, it will affect production, and should strengthen the daily maintenance of the crane.

Paper mill crane programme 5

Above the paper machine to set up a 3-trolley bridge for paper machine maintenance or backup lifting paper rolls, paper machine dry end of the ground layout of 1 to 2 half-leg electric hoist door machine (according to the paper machine production line to determine the number of units), door machine 2 hooks can be designed to be fixed on the bridge. The advantages of this layout is that the door machine is dedicated to the paper roll lifting, lateral alignment is accurate, high efficiency, mostly used in the same workshop layout has 2 or more paper machine line occasions. The disadvantage is that the total investment in equipment, infrastructure and other large, poor economy, the current application is less and less. Scheme 1, 2, 3, if the use of winch type lifting mechanism of the trolley, due to the left and right limit lifting point away from the centre line of the trolley track is farther away, generally need to configure 1 ~ 2 3.2 ~ 10t electric hoist, hanging in the main beam floor or main beam side of the outline track. If the hoist type trolley, due to the limit of small lifting point, sometimes can be exempted from the small hoist, which can reduce the cost of the crane.

At present, part of the European electric hoist design work level can reach M6. electric hoist trolley light weight, compact structure, high lifting point, both sides of the limit position is small, has been widely used in various occasions and various industries. A large number of practice has proved that, compared with the winch type trolley, the hoist trolley not only has the price advantage, but also the technical indicators and performance, life, reliability and other aspects, can completely replace the domestic QD type winch type trolley.

Kesimpulan

From years of design and manufacturing experience, from the point of view of economy, practicality and frequency of use, the order of priority programme is 3, 2, 1, 5, 4. The whole machine adopts the form of double girder crane with electric hoist, with priority to European electric hoist as the hoisting mechanism, and the large and small trolley running mechanism adopts the structure of three-in-one drive device. Reasonable selection and optimisation of paper mill crane layout, not only can greatly reduce investment costs, reduce crane maintenance costs and operating costs, but also improve efficiency, reduce downtime losses, and bring lucrative economic benefits for paper enterprises.

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