CN201792462U - Injection machine screw rod with reversely-connected screw rod head - Google Patents

Abstract

The utility model relates to an injection molding machine screw with reversely connected screw heads. The screw is mainly composed of a screw body, a thrust ring, a non-reverse ring and a screw head. The front end of the screw body has a section of smooth small-diameter cylinder and a section of stud in turn. The stud cooperates with the internal thread hole on the screw head to connect the two parts, which can have high straightness and coaxiality. The smooth small-diameter cylindrical section is covered with a thrust ring. The front end surface and the rear end surface of the thrust ring are respectively attached to the rear end surface of the screw head and the front end surface of the screw rod. When the front stud of the screw rod is screwed into the internal thread hole of the screw head to a certain depth, the thrust ring It is axially fixed, and the thrust ring can choose different outer diameters according to different materials and process requirements, so that different back pressures can be generated. The annular non-return ring is installed on the screw head cylinder between the thrust ring and the screw head, and can rotate freely, and can also move forward and backward. The plasticized melt in the tank is pressed into the storage section through the gap, the gap formed between the screw head cylinder and the barrel, and the screw head groove; when they are fitted together, the melt in the storage section is prevented from flowing back to the screw groove for sealing , the screw can be injected.

Description

Injection molding machine screw with screw head reverse connection

technical field

The utility model relates to an injection molding screw used in an injection molding machine.

Background technique

Injection screw is one of the key parts of injection molding machine. It rotates in the barrel of the injection molding machine. Its main function is to melt and plasticize the solid polymer particles or powder, store and measure, and then inject a certain amount of melt stored into the mold. After the mold is cooled, it is ejected to obtain plastic products.

The screw with ring check screw head in injection molding screw consists of the following parts: screw head, check ring, thrust ring and screw body. The non-return ring is located between the screw head and the thrust ring, and is wrapped on the cylindrical section of the screw head; the inner diameter of the anti-reverse ring and the outer diameter of the screw head cylinder form the flow path of the material, and the outer diameter forms the inner diameter of the barrel. seal. When plasticizing, the molten material in the screw groove is conveyed forward and pushes the closed non-return ring to open the flow channel, so that the melt can pass smoothly into the material storage section; when injecting, the screw head moves forward, and the non-reverse ring is The action of the material in the material storage section makes a reverse movement backward until it contacts with the tapered surface of the thrust ring to achieve a closed seal.

Traditionally, the screw head is connected with the internal thread hole in the front section of the screw through the external thread at the rear end. Generally, the screw is longer and must have a good straightness so as not to directly rub against the barrel; most of the length of the screw is processed with a screw groove, and the formed screw flight is a kind of external thread, and the screw groove and the screw flight have inverted Rounded corners and high finish require precision machining and grinding. In these processing processes, the center line of the front and rear end faces of the screw and the unthreaded smooth section of the rear section of the screw are generally used for positioning. The internal threaded hole at the front end of the conventional screw must be coaxial with the screw as a whole, so as to ensure the smooth non-friction rotation and forward and backward movement of the screw head in the barrel. In actual processing, the requirement of this coaxial line is often not easy to guarantee: the straightness of the neutral line of the internal threaded hole has a large error when drilling, and the processed internal threaded hole will be eccentric. Although the screw head and the stud have a fairly accurate straightness after grinding, once they are connected with the inner screw hole on the screw, the overall straightness is not easy to guarantee. The finished product has a high rate of deflection after the screw is connected to the screw head. And a non-straight screw will have greater wear and tear during the high temperature working process, so the durability of the injection molding machine is low.

Contents of the invention

In the traditional screw injection machine, the connection between the external thread of the rear section of the screw head and the internal thread hole of the front end of the screw is not easy to ensure the coaxiality and straightness of the screw body. To improve this problem, the internal thread hole of the screw head and the front end of the screw are used. The connection method of the external thread segment, thus forming a new type of injection molding machine screw system with reverse connection of the screw head.

Chinese utility model patent 95203759.6 also mentions a screw system of an injection molding machine with the screw head reversely connected. A stud protrudes from the front end of the screw. Set a non-reverse ring (the original text is "thrust ring" should be revised), and the end of the non-reverse ring and the screw rod are matched with each other, and a groove is made to accommodate the ball. This invention has three disadvantages completely. One is that there is no thrust ring between the screw head and the screw rod. replace. If the thrust ring is added, the thrust ring can be replaced directly, and the back pressure can be adjusted by changing the outer diameter of the thrust ring. The second is that the gap between the front end of the screw/the back end of the non-return ring, the inner cavity of the non-return ring/the small cylindrical section of the screw and the gap between the balls form a melt circulation channel that is too sudden, easy to block, and the melt flow is not smooth. This problem can be solved if the transition cylindrical section on the common screw head is kept. Third, the use of the sliding structure of the groove/ball on the end face of the screw head does not enhance the rotational freedom of the cylindrical non-return ring. On the contrary, if the balls or grooves are worn unevenly, it is easy to cause deflection. Therefore, the problem can be solved by adopting methods such as inclined end surface transition and slotting at the front end of the screw head. The specific content of the present invention will be described in detail below.

The injection molding machine screw system in the utility model is mainly composed of a screw rod, a thrust ring, a check ring, and a screw head.

In addition to the multi-stage distribution of the screw grooves of the traditional screw, the front end of the new screw body has a smooth small-diameter cylinder and a stud in turn. This stud mates with an internally threaded hole in the screw head, threading the two parts together. During processing, this section of studs can use the clamping positioning reference for screw groove processing, and even the entire screw and studs can be processed with one clamping, so as to ensure that they have high straightness and coaxiality. The screw head is short, and the straightness of the internal thread hole, the coaxiality with the maximum outer circle of the screw head and the main body section, and the perpendicularity with the rear end surface for positioning are easy to ensure and correct during processing. In this way, compared with the screw in the traditional technology, the straightness and coaxiality of the connection between the screw head and the screw body are obviously easy to ensure, which can be very accurate, and the wear of the screw and the screw head and the barrel is fundamentally reduced, and the use is more convenient. Durable and more precise.

A thrust ring can be placed on the smooth small-diameter cylindrical section at the front end of the new screw body. When the threaded hole reaches a certain depth, the thrust ring is axially fixed, and the thrust ring can be selected with different outer diameters according to different materials and process requirements, so that different back pressures can be generated.

The annular non-return ring is installed on the screw head cylinder between the thrust ring and the screw head, and can rotate freely, and can also move forward and backward. The plasticized melt in the tank is pressed into the storage section through the gap, the gap formed between the screw head cylinder and the barrel, and the screw head groove; when they are fitted together, the melt in the storage section is prevented from flowing back to the screw groove for sealing , the screw can be injected.

The front end of the screw head can be conical or cylindrical or even threaded. It can also be grooved to guide the flow. It can also be further combined with check balls, pins or static mixers to form a variety of screw head forms to meet different processes. need.

Description of drawings

Figure 1 is a schematic diagram of the structure of the screw of the injection molding machine when the forward injection check ring is closed

Figure 2 is a schematic diagram of the structure of the injection molding machine when the screw is receding and plasticized, and the check ring is fully open

Figure 3 is a schematic diagram of the screw body structure of the injection molding machine screw

Figure 4 is a schematic diagram of the structure of the thrust ring of the screw of the injection molding machine

Figure 5 is a schematic diagram of the screw head structure of the injection molding machine screw

Figure 6 is a schematic diagram of the anti-reverse ring structure of the screw of the injection molding machine

Detailed ways

The utility model injection molding machine screw is mainly composed of the following parts: screw head 1, check ring 2, thrust ring 3, screw body 4. The front end of the screw body has a section of smooth small-diameter cylinder 6 and a section of stud 8 in turn, and 7 is a stepped surface, and the thrust ring and the screw body are positioned on the contact surface 5 . The external screw thread 8 of the stud matches the internal screw hole of the screw head to connect the two parts, which can have higher straightness and coaxiality.

As shown in Figure 1, when the screw of the injection molding machine injects the material forward. The non-return ring and the thrust ring are closed at the contact surface 9. Since the material is sealed in the storage section in the barrel 0, the screw moves forward, the nozzle 16 is opened, and the material is injected into the mold through the flow channel.

As shown in Figure 2, when the screw of the injection molding machine retreats to plasticize the material. Under the action of melt pressure, the non-return ring moves forward until it contacts the screw head at the stepped surface 10 . The plasticized material in the screw groove passes through the gap 11 between the thrust ring and the inner cavity of the barrel, the gap between the non-reverse ring and the thrust ring on the contact surface 9, and the gap 12 between the non-reverse ring and the cylindrical part of the screw head. , 13, the longitudinal groove 14 on the screw head, and then enters the storage section 15 at the front of the screw head. As the pressure in the storage section increases, the check ring is pushed to move backward, and the gap between the step surface 10 increases, while the gap between the check ring and the thrust ring on the contact surface 9 decreases continuously. Since the nozzle is closed when the material is plasticized, the material will not leak through 16, and the injection is only performed when 16 is opened.

Fig. 3 is the screw body part, the front end cylinder part is composed of two parts, the front end is the external thread part matched with the screw head internal thread hole, and the other part is the smooth cylinder part, and the smooth cylinder is sleeved on the thrust ring.

As shown in Figure 4, for the thrust ring part, different outer diameters can be selected according to different materials and different processing techniques, and then different clearances between the thrust ring and the barrel can be obtained. The rear end surface of the thrust ring is positioned in close contact with the step of the large front end of the screw rod, and the front end surface of the thrust ring is positioned in close contact with the end surface of the inner hole of the screw head.

Fig. 5 is the screw head part. The cylinder part of the screw head has an internal screw hole, which is connected with the external thread of the screw body stud through the internal thread, and its large rear end surface is fitted and positioned with the front end surface of the thrust ring. In the cone part of the screw head, there is a longitudinal groove, which can guide the molten material and increase the flow space. The outer cylindrical section is fitted with a non-return ring, and the rear flange of the conical head prevents the non-return ring from passing over.

As shown in Figure 6, the non-return ring part, the ring-shaped non-return ring installed on the cylinder of the screw head can rotate freely, and can also move forward and backward. When the back side of the anti-reverse ring and the front inclined side of the thrust ring are not fully fitted, the melt in the screw groove is pressed into the storage section during plasticization; when they are fitted together, the melt in the storage section is prevented from flowing back into the screw groove. Sealing action allows for injection.

Claims (2)

1. The screw of the injection molding machine with reverse connection of the screw head is mainly composed of a screw body, a thrust ring, a check ring and a screw head. It is characterized in that the front end of the screw body has a smooth small-diameter cylinder and a stud in sequence. The internal threaded holes on the head cooperate to connect the two parts, which can have high straightness and coaxiality. 2. The injection molding machine screw according to claim 1, wherein the screw head is reversely connected, characterized in that: the smooth small-diameter cylindrical section at the front end of the screw body is covered with a thrust ring, and the front end surface and the rear end surface of the thrust ring are respectively connected to the rear end of the screw head. The end face and the front end of the screw fit together. When the stud at the front end of the screw is screwed into the internal threaded hole of the screw head to a certain depth, the thrust ring is axially fixed. The thrust ring can choose different outer diameters according to different materials and process requirements, so that Different back pressures can be generated. The annular non-return ring is installed on the screw head cylinder between the thrust ring and the screw head, and can rotate freely, and can also move back and forth, so that the plasticized melt in the screw groove flows into the storage section or prevents the storage section from melting. Body countercurrent injection.

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