阅读说明：本技术 专用于生产pbt塑料棒的工艺方法 (Special process method for producing PBT plastic rod ) 是由 刘福华 于 2020-07-04 设计创作，主要内容包括：本发明提供一种专用于生产PBT塑料棒的工艺方法,所述工艺包括：烘干,去除水分：塑化挤出,采用特定温度分三区加热机筒,采用特定结构的PBT炮筒螺杆以及特定挤出速度；均化分流,主模分四区以使熔体进一步均化；成型/定型,直线流动的熔体通过主模出口被均匀流入导流板,通过导流板进行分流,分别进入多棒成型模的成型管,熔体在成型管内的压缩成型区成型；裁切。本发明克服了棒材内应力过大造成的收缩变形或开裂报废,棒材耐冲击力更好,表面光滑,几乎没有熔悍缝。(The invention provides a special process method for producing a PBT plastic rod, which comprises the following steps: drying and removing water: plasticizing and extruding, namely heating a barrel in three zones at a specific temperature, and adopting a PBT barrel screw with a specific structure and a specific extrusion speed; homogenizing and shunting, and dividing the main mold into four regions to further homogenize the melt; molding/shaping, wherein the melt flowing in a straight line uniformly flows into a guide plate through an outlet of the main mold, is shunted by the guide plate and respectively enters a molding pipe of a multi-rod molding mold, and the melt is molded in a compression molding area in the molding pipe; and (6) cutting. The invention overcomes the shrinkage deformation or cracking scrap caused by overlarge internal stress of the bar, and the bar has better impact resistance, smooth surface and almost no weld seam.)

1. A special process method for producing PBT plastic rods is characterized by comprising the following steps:

drying: drying the PBT plastic granules by circulating hot air at 100 ℃ to ensure that the water content of the PBT plastic granules is lower than 0.2%;

plasticizing and extruding: the PBT plastic granules are converted into uniform continuous melt with certain fluidity by the action of the temperature of a machine barrel and an extrusion screw rod and are extruded; wherein, divide into three district and heat to the barrel around:

the temperature of the feeding section in the first area is 240 ℃ and 250 ℃;

the temperature of the second-zone melting compression section is 250-260 ℃;

The temperature of the three-zone homogenizing section is 250-270 ℃;

the joint temperature is 260 ℃ and 270 ℃;

the extrusion screw is a special PBT gun barrel screw with the equidistant gradual change type, the length-diameter ratio of the screw is 25: 1, the compression ratio is 3.3, and the extrusion speed is 30-35 r/min;

homogenizing and shunting: under the rotary extrusion of the extrusion screw, the melt enters a main die through a material nozzle, is further homogenized in the main die, and is converted into linear motion from spiral motion; the master mold is divided into four regions to set constant temperature:

the temperature of the former zone is 260 ℃ and 270 ℃;

the temperature of the first two areas is 250-260 ℃;

the temperature of the latter zone is 250-260 ℃;

the temperature of the second zone is 240 ℃ and 250 ℃;

molding/shaping: the melt flowing in a straight line uniformly flows into a guide plate through the outlet of the main die, is shunted by the guide plate and respectively enters a forming pipe of a multi-rod forming die, and the melt is formed in a compression forming area in the forming pipe; wherein

The homogenization temperature of the guide plate is 250-260 ℃;

the shaping temperature of the shaping area of the shaping pipe is 140-160 ℃;

cutting: and cutting the formed bar into a preset length.

2. The process method special for producing the PBT plastic rod according to claim 1, which further comprises a post heat treatment step after cutting:

Carrying out heat treatment on the stacked PBT bars, and dividing the heat treatment into eleven sections:

3. the process for producing PBT plastic rod according to claim 2, wherein after the shaping/fixing, further comprising:

traction: the shaped bar is drawn by the drawing mechanism, so that the melt is in the compression molding area to form certain pressure, and the structural compactness of the bar is improved.

Technical Field

The invention relates to a special process method for producing a PBT plastic rod.

Background

PBT (polybutylene terephthalate) molding is that granular materials are added into a machine barrel of an extruder from a hopper, the materials are conveyed forward and compacted under the extrusion pushing action of the rotation of a screw rod through the friction action of the inner wall of the machine barrel and the surface of the screw rod, and are melted and plasticized under the conditions of high temperature and high pressure through a heating device and friction preheating outside the machine barrel. Then, the continuously rotating screw pushes the molten material into a head die, and the molten material extruded from the head die is cooled and shaped into the required PBT product.

The PBT rod forming process comprises the following steps: feeding, drying, plasticizing and extruding, molding and shaping, cutting/stacking and the like.

At present, in the process of preparing the PBT rod, plasticizing extrusion is divided into three zones to heat a machine barrel:

the temperature of the feeding section in the first area is 260 ℃ and 270 ℃;

the temperature of the second-zone melting compression section is 260-270 ℃;

the temperature of the three-zone homogenizing section is 270-280 ℃;

the joint temperature is 250 ℃ and 260 ℃;

the length-diameter ratio of the screw is 30: 1, the compression ratio is 3, and the extrusion speed is 25-30 r/min.

In the molding and shaping process, the mixture enters a machine head body (the temperature of the machine head body is 250-260 ℃) under the rotating and shearing action of a screw rod and then enters a single rod mold for direct molding, the temperature is continuously reduced under the action of cooling water after molding, and finally the mixture is solidified, crystallized and shaped to be extruded out of the single rod mold.

The subsequent heat treatment is divided into eleven sections:

a first stage: the heating temperature is 45 ℃ and the heating time is 100 minutes;

and a second stage: the constant temperature is 50 ℃ and the constant temperature time is 3 x 70 minutes in thickness;

a third stage: the heating temperature is 75 ℃, and the heating time is 20 minutes;

a fourth stage: keeping the temperature at 90 ℃ for 200 minutes;

a fifth stage: the heating temperature is 100 ℃, and the heating time is 30 minutes;

a sixth stage: keeping the temperature at 130 ℃ for 150 minutes;

A seventh stage: the heating temperature is 100 ℃, and the heating time is 10 minutes;

an eighth stage: keeping the temperature at 60 ℃ for 180 minutes;

a ninth stage: the heating temperature is 60 ℃, and the heating time is 60 minutes;

a tenth stage: keeping the temperature at 60 ℃ for 180 minutes;

an eleventh stage: the temperature is reduced to 60 ℃ for 20 minutes.

The problems of the above process are: 1. the bar has low impact resistance; 2. the surface is not smooth and has welding and welding seams; 3. the internal stress of the bar is large; 4. the processing is easy to crack.

Disclosure of Invention

In view of the above, it is necessary to provide a special process for producing PBT plastic rod to solve the above technical problems.

The invention provides a special process method for producing a PBT plastic rod, which comprises the following steps:

drying: drying the PBT plastic granules by circulating hot air at 100 ℃ to ensure that the water content of the PBT plastic granules is lower than 0.2%;

plasticizing and extruding: the PBT plastic granules are converted into uniform continuous melt with certain fluidity by the action of the temperature of a machine barrel and an extrusion screw rod and are extruded; wherein, divide into three district and heat to the barrel around:

the temperature of the feeding section in the first area is 240 ℃ and 250 ℃;

the temperature of the second-zone melting compression section is 250-260 ℃;

The temperature of the three-zone homogenizing section is 250-270 ℃;

the joint temperature is 260 ℃ and 270 ℃;

the extrusion screw is a special PBT gun barrel screw with the equidistant gradual change type, the length-diameter ratio of the screw is 25: 1, the compression ratio is 3.3, and the extrusion speed is 30-35 r/min;

homogenizing and shunting: under the rotary extrusion of the extrusion screw, the melt enters a main die through a material nozzle, is further homogenized in the main die, and is converted into linear motion from spiral motion; the master mold is divided into four regions to set constant temperature:

the temperature of the former zone is 260 ℃ and 270 ℃;

the temperature of the first two areas is 250-260 ℃;

the temperature of the latter zone is 250-260 ℃;

the temperature of the second zone is 240 ℃ and 250 ℃;

molding/shaping: the melt flowing in a straight line uniformly flows into a guide plate through the outlet of the main die, is shunted by the guide plate and respectively enters a forming pipe of a multi-rod forming die, and the melt is formed in a compression forming area in the forming pipe; wherein

The homogenization temperature of the guide plate is 250-260 ℃;

the shaping temperature of the shaping area of the shaping pipe is 140-160 ℃;

cutting: and cutting the formed bar into a preset length.

Further, the method also comprises a post heat treatment step after cutting:

carrying out heat treatment on the stacked PBT bars, and dividing the heat treatment into eleven sections:

First-stage heating temperature 40 ℃ heating time: 120 minutes;

the second-stage constant temperature is 70 ℃ and the constant temperature time is as follows: thickness 3 x 60 minutes;

the third-stage heating temperature is 70 ℃ and the heating time is as follows: 20 minutes;

the fourth constant temperature is 100 ℃ for constant time: 180 minutes;

the fifth stage heating temperature is 120 ℃ for heating time: 20 minutes;

the sixth constant temperature is 100 ℃ for constant time: 180 minutes;

the seventh stage heating temperature is 70 ℃ for heating time: 20 minutes;

the eighth constant temperature is 40 ℃ constant temperature time: 180 minutes;

heating temperature of the ninth section at 40 ℃ for a heating time: 40 minutes;

the constant temperature of the tenth section is 40 ℃ for a constant time: 180 minutes;

the eleventh stage of cooling temperature is 40 ℃ cooling time: for 150 minutes.

Further, after the forming/shaping, the method further comprises the following steps:

traction: the shaped bar is drawn by the drawing mechanism, so that the melt is in the compression molding area to form certain pressure, and the structural compactness of the bar is improved.

According to the invention, through the selection of the process steps and the setting of the process parameters, the shrinkage deformation or cracking scrappage caused by overlarge internal stress of the bar is overcome, the bar has better impact resistance and smooth surface, and almost no welding seam exists.

Drawings

Fig. 1 is a schematic structural view of a production apparatus according to an embodiment of the present invention.

Detailed Description

The special process method for producing the PBT plastic rod is produced by the special production equipment for PBT shown in FIG. 1. As shown in fig. 1, the equipment comprises a motor 1, a reduction gearbox 2, a hopper 4, a dryer 3, a control cabinet 5, a PBT special barrel screw 6, a flange joint 7, a connecting square plate 8, a feeding hole 9, a main mold 10, a mold frame 12, a guide plate 11, a forming pipe 13, a tractor 14, a cutter 15, an oven and the like.

The motor 1, the reduction gearbox 2, the hopper 4, the dryer 3, the control cabinet 5, the PBT special gun barrel screw 6 and the like can form a main machine part of the equipment, and the main mold 10, the mold frame 12, the guide plate 11, the heat insulation ring 14, the forming pipe 13, the tractor 14, the cutting machine 15, the oven and the like can form an auxiliary machine part of the equipment.

The motor 1 and the reduction gearbox 2 form a rotating system, the motor 1 runs and drives the reduction gearbox 2 through belt transmission, and therefore the special barrel screw 6 for the PBT keeps a certain shearing rate. The special parameters of the PBT special gun barrel screw 6 are as follows: the length-diameter ratio is 25: 1, compression ratio of 3.3.

The control cabinet 5 can be internally provided with a control system which specifically comprises an electrical instrument and an actuating mechanism and has the main function of controlling the main machine, so that the rotating speed and the power of the operation of the main machine are normal, the temperature, the pressure, the flow and the quality of products of the main machine and the auxiliary machine are ensured, and the automatic control of the whole machine set is realized.

The master mold 10 is provided on a mold frame 12. The melt enters the main die 10 through the feed opening 9. The two sides of the flow inlet channel diversion stop block are shunted, the shunted melt enters the eight bellmouths of the guide plate 11 and the forming tube 13 under certain pressure, and is formed and shaped in the forming tube 13 under the constant-temperature shaping state of certain pressure and oil temperature.

The forming tube 13 includes a compression forming zone and a setting zone. The oil temperature machine is arranged in the shaping area of the forming pipe 13, and the products in the shaping area are shaped at constant and balanced temperature and smoothly extruded out of the die through continuous circulation of hot oil.

The tractor 14 mainly comprises a transmission device, a roller pressing device and a brake device, the main die 13 and the tractor 14 are fixed together through a connecting rod, the air control tractor 14 is connected with the square plates 8 up and down, and the speed reducer drags the rollers to enable products to keep a certain pressure in a compression area and move forward at a constant speed.

The cutter 15 is a bar cutting device installed at the rear, and the extruded product passes through a cutting support surface of the cutter 15, and the bar is cut into a desired length product by high-speed rotation of a saw blade.

The oven is of a sealed box body structure, different temperatures are set through a temperature controller, and heat treatment is carried out on the product in different time and in different sections.

The invention provides a special process method for producing PBT plastic rods, which mainly comprises the following steps: feeding, drying, plasticizing and extruding, homogenizing and shunting, forming/shaping, drawing, cutting, stacking and heat treating.

The following focuses on the specific process steps of one embodiment of the present invention.

1. Feeding: when feeding, the materials should be fed in time to ensure that the hopper 4 is not empty. Different materials can not be used in a mixed mode, the grade of the clear materials and the type of the materials are noticed, and sundries are prevented from entering the hopper 4 to cause the blockage of the feed opening.

2. Drying: because the PBT resin has larger temperature absorption, the PBT resin needs to be dried before extrusion molding to remove moisture, otherwise, the moisture content exceeds a certain limit, and the moisture can be volatilized into gas in an extruder barrel, so that air holes are contained in the product, and the strength of the product is reduced.

In the step, aiming at the characteristics of the PBT plastic granules, the PBT plastic granules are dried by 100 ℃ circulating hot air for 2-4H, so that the moisture content in the product is lower than 0.2%, and the preheating effect of the PBT plastic granules is realized while the PBT plastic granules are dried by 100 ℃ circulating hot air.

3. Plasticizing and extruding: the PBT plastic granules are converted into a uniform continuous melt with certain fluidity by the action of the temperature of a cylinder and an extrusion screw and are extruded.

The extrusion screw is a special PBT gun barrel screw with the equidistant gradual change type, the length-diameter ratio of the screw is 25: 1, compression ratio of 3.3.

Wherein, the barrel is heated by dividing the front zone and the rear zone into three zones, and the temperature of the feeding section in one zone is 240-; the temperature of the two-zone melting compression section is 250-; the temperature of the three-zone homogenization zone is 250-; the linker temperature is 260 ℃ and 270 ℃ (such as 261 ℃, 262 ℃, 263 ℃, 264 ℃, 265 ℃, 266 ℃, 267 ℃, 268 ℃ and 269 ℃); the extrusion rate is 30-35r/min (e.g., 31r/min, 32r/min, 33r/min, 34 r/min).

By selecting a specific screw length-diameter ratio, a specific compression ratio, a specific three-zone heating temperature, a specific joint temperature and a specific extrusion speed, PBT plastic granules can be more completely plasticized, melted and extruded to form a bar product, and the stress, the air holes, the mechanical properties and the like of the bar product are influenced by the setting of each parameter.

4. Homogenizing and shunting: under the rotary extrusion of the extrusion screw, the melt enters a main die through a material nozzle, is further homogenized in the main die, and is converted into linear motion from spiral motion.

The master mold is divided into four zones with constant temperature, and the temperature of the former zone is 260-; the temperature of the first two zones is 250-260 deg.C (such as 251 deg.C, 252 deg.C, 253 deg.C, 254 deg.C, 255 deg.C, 256 deg.C, 257 deg.C, 258 deg.C, 259 deg.C); the temperature of the latter zone is 250 ℃ and 260 ℃ (such as 251 ℃, 252 ℃, 253 ℃, 254 ℃, 255 ℃, 256 ℃, 257 ℃, 258 ℃ and 259 ℃); the temperature of the second zone is 240 ℃ and 250 ℃ (e.g., 241 ℃, 242 ℃, 243 ℃, 244 ℃, 245 ℃, 246 ℃, 247 ℃, 248 ℃ and 249 ℃).

5. Molding/shaping: the melt flowing in a straight line is uniformly flowed into a guide plate 11 through an outlet of the main die 10, and is divided by the guide plate 11 and respectively enters a forming tube of a multi-rod forming die, and the melt is formed in a compression forming area in the forming tube. The homogenization temperature of the flow guide plate is 250-260 ℃ (such as 251 ℃, 252 ℃, 253 ℃, 254 ℃, 255 ℃, 256 ℃, 257 ℃, 258 ℃ and 259 ℃); the shaping temperature of the shaping zone of the shaping tube is 140-160 deg.C (such as 141 deg.C, 142 deg.C, 143 deg.C, 144 deg.C, 145 deg.C, 146 deg.C, 147 deg.C, 148 deg.C, 149 deg.C, 150 deg.C, 151 deg.C, 152 deg.C, 153 deg.C, 154 deg.C, 155 deg.C, 157 deg.C, 158 deg.C.

And (4) combining the step 4, carrying out constant temperature on the main mold in four zones, carrying out flow distribution through the guide plates, and adopting the specific guide plate temperature and the forming tube forming temperature to obtain the mutual matching of melt flowability and forming requirements, so that the rod product can be smoothly extruded, and the obtained rod has high surface smoothness.

6. Traction: a brake seat is arranged at the outlet position of the main die 10 of the heat preservation device, the tightness of a brake strip is adjusted through the brake seat to clamp a bar product, and a traction mechanism 14 is used for drawing a shaped bar so as to enable a melt to form certain pressure in the compression molding area, so that the structural compactness of the bar is improved, and the thickness of the bar is adjusted to achieve eccentricity.

7. Cutting: the tape measure measures 1000MM in length, and the cutter is started to cut out the required length.

8. Stacking: hoisting the plate by using a sucker to hoist the block, and neatly stacking the plate on a specific stacking frame; stainless square steel is placed between the rod layers, and the square steel between the layers is preferably seen on the upper and lower sides in a straight line.

9. And (3) post heat treatment: carrying out heat treatment on the stacked PBT bars through an oven, wherein the heat treatment is divided into eleven sections:

first-stage heating temperature 40 ℃ heating time: 120 minutes;

The second-stage constant temperature is 70 ℃ and the constant temperature time is as follows: thickness 3 x 60 minutes;

third-stage heating temperature 70 ℃ heating time: 20 minutes;

the fourth constant temperature is 100 ℃ for constant time: 180 minutes;

the fifth stage heating temperature is 120 ℃ for heating time: 20 minutes;

the sixth constant temperature is 100 ℃ for constant time: 180 minutes;

seventh-stage warming temperature 70 ℃ warming time: 20 minutes;

the eighth constant temperature is 40 ℃ constant temperature time: 180 minutes;

ninth stage heating temperature 40 ℃ heating time: 40 minutes;

the constant temperature of the tenth section is 40 ℃ for a constant time: 180 minutes;

the temperature reduction temperature of the eleventh section is 40 ℃ for the temperature reduction time: for 150 minutes.

Through the specific later-stage heat treatment steps, the PBT bar product is subjected to specific-temperature heat treatment in specific time and multiple sections, so that the residual internal stress of the PBT bar product can be effectively eliminated, and the quality and the stability of the PBT bar are ensured.

The PBT bars were tested according to the following test items and results:

item	Standard of merit	Unit of	Numerical value
				Density of	ASTMD792	g/cm3	1.31
Tensile strength at yield	ASTMD638	Mpa	80
				Elongation at break	ASTMD638	％	4
Bending strength	ASTM790	Mpa	100
				Flexural modulus	ASTM790	Mpa	2400
Shore hardness	ASTMD2240	Mpa	90
				Impact strength	ASTMD256	J/M	70
Thermal conductivity	DIN52612-1	W/(K-M)	0.24

The specific parameters are finally determined by the inventor of the invention through repeated large amount of specific experiments and time-consuming years and are suitable for producing the PBT plastic rod, the parameters are interdependent but not isolated, the selection of the parameters is very important, the parameters are matched together to finally obtain the expected PBT plastic rod, and through the steps of the specific process method, the prepared PBT plastic rod overcomes the defects of shrinkage deformation or cracking scrap caused by overlarge internal stress, avoids the defect of serious waste, has few air hole impurities in the product, ensures the quality of the product and greatly improves the yield of qualified products.