The range of solid materials is very wide, and can be divided into powder, granules, and lumps according to the form; according to the viscosity, it can be divided into non-adhesive, semi-viscous, and viscous three categories.
Non-sticky material. Such as dry grains, seeds, rice, sugar, coffee, granulated salt, crystalline rock sugar and various dried fruits, these materials can freely flow, dumped on the horizontal surface, can be naturally piled into a conical pile, so it is also called free flow. Material is the most easily filled type; semi-viscous materials, such as flour, powder monosodium glutamate, powdered milk, white sugar, washing powder, penicillin powder, etc., cannot flow freely. When filled, they are bridged or stacked in the storage hopper and the lower hopper. Arched, resulting in difficulty in filling, requires the use of special devices; sticky materials, such as brown sugar powder, candied fruit, and some chemical raw materials, etc., are more difficult to fill, they not only bind themselves into clumps, and even adhere to the metal wall and gather together. The surface of the vinyl fluoride coating (used to reduce the friction between the material and the metal wall and increase the abrasion resistance of the material bucket) makes the filling more difficult, and some of them cannot be automatically filled by mechanical means at all. It should be noted that some loose powders and granular materials become sticky when the temperature rises or becomes wet. Therefore, the temperature and humidity of the shop should be controlled when filling.
Solid material filling methods can be divided into three categories: one is weighing filling method, which is to measure the amount of filling material by weight; the Other is volume filling method, which is to calculate the quantity of filling material by volume; Classes are counting methods, which are commonly used for collective packaging. The filling of bulk, granular materials of solid materials is measured by the amount of bulk, granular solid material, or the number of individual packaging items.
I. Weighing filling method Weighing filling method is applicable to the filling of materials that are easy to absorb moisture, easy to agglomerate, non-uniform particle size, and have a relatively large specific gravity. This type of filling method is divided into two types: net weight filling and gross weight filling.
1. Net-filling method This method uses materials to be weighed and then filled into containers. The weighing result is not affected by changes in the weight of the container and is therefore the most accurate weighing method. As shown in Fig. 9-11, the filling result is that the material is conveyed from the hopper to the weighing hopper 3 by a feeder 2, and weighed by the scale 4 continuously. When the material in the weighing hopper reaches the prescribed weight, the material is discharged through the hopper 5 and enters the packaging container. The feed can be done with a rotary feeder, a belt, an auger, or other means, and the weighing can be controlled with a mechanical scale, an electronic scale, or a combination scale. Mechanical devices, photocells or limit switches can be used to achieve the specified weight.
Due to the high net weight weighing accuracy, such as 500g material, its weighing accuracy can reach ± ​​0.5g, that is, the accuracy can reach ± ​​0.1%, so it is widely used in precision requirements or precious free flowing solid materials, can also be used Those materials that are not suitable for volume-packed packaging, such as expanded corn, fried potato chips, fried shrimp, etc. However, the net weight filling method is slow, and the price of the machine used is high.
2. The gross weight filling method loads the material into the container and weighs it together with the container. The weight weighed is the gross weight. This method uses a simple machine with low prices. The disadvantage is that the weight change of the packaging container itself directly affects the specified weight of the filling material. As shown in Figure 9-12, the difference from the net weight is that there is no weighing bucket, but the container is placed on the scale for filling. When the specified weight is reached, the feeding is stopped, and the weight weighed is heavy.
The gross weight filling is not suitable for occasions where the weight of the packaging container varies greatly and the weight of the material accounts for a small percentage of the entire weight. For example, a glass bottle containing 25 g of pepper has a weight change of 5.9%. This variation is measured using a very accurate gross weight and must be reflected in the final package weight.
Second, volume filling method This method is based on the volume to measure the amount of filling materials, because no weighing device, the machine used is simple, the filling speed can be improved. However, the accuracy of the filling depends on the stability of the specific gravity of the material and is generally lower than that of the weighing and is ±1.0% to ±2.0%.
There are many kinds of machines that realize volume filling, but in principle, it basically belongs to two kinds.
1. Control the filling material flow rate or time to ensure the filling volume.
(1) The timing vibratory filling machine has the lowest accuracy, but the structure is the simplest and the price is cheap. The principle is shown in Figure 9-13. A vibration tray feeder 2 is connected to the lower portion of the hopper 1. The feeder oscillates at a specified time and the material is filled directly into the container. The amount of filling is controlled by the vibration time.
(3) Vacuum filling machine. During the filling process, the vacuum is maintained in the container to make the material more dense and reduce the bridge void (ie, the materials support each other to form an arch shape). Therefore, the filling accuracy is higher than that of the timing vibratory filling machine and the screw filling machine. The principle is shown in Figure 9-15. Each container is evacuated through the screen so that it must be sealed between the container and the vacuum head during filling. The material enters the container by gravity. In order to control the filling quantity, a screw feeder is installed in the storage hopper to feed the vacuum head.
2. Measure the material with the same metering container to ensure the filling volume (1) Gravity-weight cylinder filling machine. This filling machine is suitable for filling free-flowing solid materials with low price and low filling accuracy. As shown in Figure 9-16. The lower part of the supply hopper 1 is equipped with two or more metering cylinders 3 uniformly distributed on the rotating horizontal circular plate. The upper part of the measuring cylinder has a telescopic chamber 4 which can be telescoped up and down to adjust its volume. As the metering drum passes under the feed hopper during rotation, the material falls into the metering drum by gravity. Then, when the discharge opening below the metering cylinder is aligned with the round hole on the fixed tray below the cavity assembly 5, the material is discharged into the packaging container through the discharge tube 6. In order to allow the material to quickly flow into the container, the container is sometimes vibrated.
Non-sticky material. Such as dry grains, seeds, rice, sugar, coffee, granulated salt, crystalline rock sugar and various dried fruits, these materials can freely flow, dumped on the horizontal surface, can be naturally piled into a conical pile, so it is also called free flow. Material is the most easily filled type; semi-viscous materials, such as flour, powder monosodium glutamate, powdered milk, white sugar, washing powder, penicillin powder, etc., cannot flow freely. When filled, they are bridged or stacked in the storage hopper and the lower hopper. Arched, resulting in difficulty in filling, requires the use of special devices; sticky materials, such as brown sugar powder, candied fruit, and some chemical raw materials, etc., are more difficult to fill, they not only bind themselves into clumps, and even adhere to the metal wall and gather together. The surface of the vinyl fluoride coating (used to reduce the friction between the material and the metal wall and increase the abrasion resistance of the material bucket) makes the filling more difficult, and some of them cannot be automatically filled by mechanical means at all. It should be noted that some loose powders and granular materials become sticky when the temperature rises or becomes wet. Therefore, the temperature and humidity of the shop should be controlled when filling.
Solid material filling methods can be divided into three categories: one is weighing filling method, which is to measure the amount of filling material by weight; the Other is volume filling method, which is to calculate the quantity of filling material by volume; Classes are counting methods, which are commonly used for collective packaging. The filling of bulk, granular materials of solid materials is measured by the amount of bulk, granular solid material, or the number of individual packaging items.
I. Weighing filling method Weighing filling method is applicable to the filling of materials that are easy to absorb moisture, easy to agglomerate, non-uniform particle size, and have a relatively large specific gravity. This type of filling method is divided into two types: net weight filling and gross weight filling.
1. Net-filling method This method uses materials to be weighed and then filled into containers. The weighing result is not affected by changes in the weight of the container and is therefore the most accurate weighing method. As shown in Fig. 9-11, the filling result is that the material is conveyed from the hopper to the weighing hopper 3 by a feeder 2, and weighed by the scale 4 continuously. When the material in the weighing hopper reaches the prescribed weight, the material is discharged through the hopper 5 and enters the packaging container. The feed can be done with a rotary feeder, a belt, an auger, or other means, and the weighing can be controlled with a mechanical scale, an electronic scale, or a combination scale. Mechanical devices, photocells or limit switches can be used to achieve the specified weight.
Due to the high net weight weighing accuracy, such as 500g material, its weighing accuracy can reach ± ​​0.5g, that is, the accuracy can reach ± ​​0.1%, so it is widely used in precision requirements or precious free flowing solid materials, can also be used Those materials that are not suitable for volume-packed packaging, such as expanded corn, fried potato chips, fried shrimp, etc. However, the net weight filling method is slow, and the price of the machine used is high.
2. The gross weight filling method loads the material into the container and weighs it together with the container. The weight weighed is the gross weight. This method uses a simple machine with low prices. The disadvantage is that the weight change of the packaging container itself directly affects the specified weight of the filling material. As shown in Figure 9-12, the difference from the net weight is that there is no weighing bucket, but the container is placed on the scale for filling. When the specified weight is reached, the feeding is stopped, and the weight weighed is heavy.
The gross weight filling is not suitable for occasions where the weight of the packaging container varies greatly and the weight of the material accounts for a small percentage of the entire weight. For example, a glass bottle containing 25 g of pepper has a weight change of 5.9%. This variation is measured using a very accurate gross weight and must be reflected in the final package weight.
Second, volume filling method This method is based on the volume to measure the amount of filling materials, because no weighing device, the machine used is simple, the filling speed can be improved. However, the accuracy of the filling depends on the stability of the specific gravity of the material and is generally lower than that of the weighing and is ±1.0% to ±2.0%.
There are many kinds of machines that realize volume filling, but in principle, it basically belongs to two kinds.
1. Control the filling material flow rate or time to ensure the filling volume.
(1) The timing vibratory filling machine has the lowest accuracy, but the structure is the simplest and the price is cheap. The principle is shown in Figure 9-13. A vibration tray feeder 2 is connected to the lower portion of the hopper 1. The feeder oscillates at a specified time and the material is filled directly into the container. The amount of filling is controlled by the vibration time.
(3) Vacuum filling machine. During the filling process, the vacuum is maintained in the container to make the material more dense and reduce the bridge void (ie, the materials support each other to form an arch shape). Therefore, the filling accuracy is higher than that of the timing vibratory filling machine and the screw filling machine. The principle is shown in Figure 9-15. Each container is evacuated through the screen so that it must be sealed between the container and the vacuum head during filling. The material enters the container by gravity. In order to control the filling quantity, a screw feeder is installed in the storage hopper to feed the vacuum head.
2. Measure the material with the same metering container to ensure the filling volume (1) Gravity-weight cylinder filling machine. This filling machine is suitable for filling free-flowing solid materials with low price and low filling accuracy. As shown in Figure 9-16. The lower part of the supply hopper 1 is equipped with two or more metering cylinders 3 uniformly distributed on the rotating horizontal circular plate. The upper part of the measuring cylinder has a telescopic chamber 4 which can be telescoped up and down to adjust its volume. As the metering drum passes under the feed hopper during rotation, the material falls into the metering drum by gravity. Then, when the discharge opening below the metering cylinder is aligned with the round hole on the fixed tray below the cavity assembly 5, the material is discharged into the packaging container through the discharge tube 6. In order to allow the material to quickly flow into the container, the container is sometimes vibrated.
Wity Machinery Co., Ltd. , http://www.raprintingmachine.com