CN219381399U - Screw thread drawing device for injection mold - Google Patents

Abstract

The application relates to the technical field of injection molding, and discloses a screw thread drawing device for an injection mold, which comprises a bracket, a nut, a screw, a driving motor and a torque limiter, wherein the bracket is fixed relative to the injection mold; the nut is arranged on the bracket; the screw rod can penetrate the nut in a rotating way, and moves along the axial direction of the screw rod in a two-way when the screw rod rotates in a two-way; the driving motor is arranged on the bracket and is connected with the screw rod through a transmission mechanism in a transmission way; the torque limiter set up in drive mechanism uses the screw thread device that draws disclosed in this application, can avoid screw rod fracture or screw thread damage when the adhesion between screw rod and the material of moulding plastics is too big.

Description

Screw thread drawing device for injection mold

Technical Field

The application relates to the technical field of injection molding, for example, to a thread drawing device for an injection mold.

Background

In the injection molding process, an injection molding product is formed into an internal thread through a screw rod, and the screw rod needs to be unscrewed after an injection molding material is solidified to finish demolding. In the case where the adhesion between the screw and the injection molding material is large, the screw is easily stuck and difficult to unscrew.

In order to avoid the screw rod from being blocked, a screw thread removing die mechanism of a gear motor with a chain sprocket is disclosed in the related art, wherein a B plate, a C plate, a gear fixing plate and a backing plate are sequentially and fixedly connected through screw locking, the backing plate is connected with the backing plate through a limit screw, a movement distance S is arranged between the limit screw and the backing plate, and the movement distance S is larger than the length B of threads on a product, namely S > B; the ejector rod is fixed on the ejector pin backing plate through screws, the first graphite self-lubricating guide sleeve and the second graphite self-lubricating guide sleeve are respectively fixed on the gear fixing plate and the backing plate, a first gasket and a second gasket are arranged at the rear part of the second graphite self-lubricating guide sleeve, a linear spring is arranged between the two gaskets, a clamp spring is arranged at the rear part of the second gasket, a chain and a motor sprocket are connected with a main rotating shaft, a first deep groove bearing and a second deep groove bearing are respectively arranged at the front and rear of the main rotating shaft, the main rotating shaft is meshed with a main gear, the main gear is meshed with a slave gear, the slave gear is meshed with a forming inlay shaft, a positioning block is arranged at the rear part of the second graphite self-lubricating guide sleeve, and a speed reducing motor is fixed on the gear fixing plate and the backing plate through a connecting block and screws. The clamping phenomenon at the moment when the forming insert shaft starts to move is prevented by the gasket, the linear spring and the positioning block.

In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:

the linear spring applies an outward thrust force to the screw rod along the axial direction of the screw rod, so that screw rod fracture or thread damage is easy to occur under the condition of high rotation resistance of the screw rod.

It should be noted that the information disclosed in the foregoing background section is only for enhancing understanding of the background of the present application and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview, and is intended to neither identify key/critical elements nor delineate the scope of such embodiments, but is intended as a prelude to the more detailed description that follows.

The embodiment of the disclosure provides a screw thread drawing device for an injection mold, so as to avoid screw fracture or thread damage during demolding.

In some embodiments, the screw thread extracting device for the injection mold comprises a bracket, a nut, a screw, a driving motor and a torque limiter, wherein the bracket is fixed in position relative to the injection mold; the nut is arranged on the bracket; the screw rod can penetrate the nut in a rotating way, and moves along the axial direction of the screw rod in a two-way when the screw rod rotates in a two-way; the driving motor is arranged on the bracket and is connected with the screw rod through a transmission mechanism in a transmission way; the torque limiter is arranged on the transmission mechanism.

In some embodiments, the transmission mechanism comprises a first transmission gear and a second transmission gear, wherein the first transmission gear is sleeved on the output shaft of the driving motor and rotates together with the output shaft of the driving motor; the second transmission gear is sleeved on the screw and rotates along with the screw, and the second transmission gear is in transmission connection with the first transmission gear.

In some embodiments, the transmission mechanism further comprises a speed reducing structure, wherein the input end is in transmission connection with the first transmission gear, and the output end is in transmission connection with the second transmission gear.

In some embodiments, the speed reducing structure comprises a rotating shaft, a first speed reducing gear and a second speed reducing gear, wherein the rotating shaft is rotatably arranged on the bracket and is parallel to the screw; the first reduction gear is arranged on the rotating shaft and is in transmission connection with the first transmission gear; the second speed reducing gear is arranged on the rotating shaft and rotates along with the rotating shaft, and the second speed reducing gear is meshed with the second transmission gear.

In some embodiments, the thickness of the second reduction gear is greater than the thickness of the second drive gear, and the second drive gear is always meshed with the second reduction gear as it moves in the axial direction of the screw.

In some embodiments, the transmission mechanism further comprises a belt provided with tooth grooves, and the first reduction gear is in transmission connection with the first transmission gear through the belt.

In some embodiments, the torque limiter comprises a first torque limiter disposed between the output shaft of the drive motor and the first transfer gear.

In some embodiments, the torque limiter further comprises a second torque limiter disposed between the second drive gear and the screw.

In some embodiments, the thread drawing device further comprises a first limiting table fixed on the bracket, and the first face of the second transmission gear abuts against the first limiting table when the screw moves to the first position in the first direction.

In some embodiments, the thread drawing device further comprises a second limiting table fixed on the bracket, and the second face of the second transmission gear abuts against the second limiting table when the screw moves to the second position in the second direction.

The screw thread drawing device for the injection mold provided by the embodiment of the disclosure can realize the following technical effects:

the torque force born by the screw rod can be effectively limited through the torque limiter, and when the adhesive force between the screw rod and the injection molding material is large, the drive connection between the drive motor and the screw rod is interrupted through the disconnection of the torque limiter, so that the screw thread damage or the screw rod fracture is avoided.

The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which like reference numerals refer to similar elements, and in which:

FIG. 1 is a schematic view of a screw-threaded device for an injection mold according to an embodiment of the present disclosure;

FIG. 2 is a schematic view of an embodiment of the present disclosure after removing a portion of the structure of a screw extractor for an injection mold;

FIG. 3 is an enlarged partial schematic view at C in FIG. 2;

FIG. 4 is a schematic structural view of another thread-extracting apparatus for an injection mold provided in an embodiment of the present disclosure;

FIG. 5 is a schematic cross-sectional view taken along line A-A of FIG. 4;

fig. 6 is a schematic structural view of another thread drawing device for an injection mold according to an embodiment of the present disclosure.

Reference numerals:

100: a bracket; 110: a first substrate; 120: a second substrate; 140: a first limit table; 150: the second limiting table; 200: a driving motor; 210: a nut; 220: a screw; 310: a first torque limiter; 320: a second torque limiter; 410: a first transmission gear; 420: a second transmission gear; 431: a first reduction gear; 432: a second reduction gear; 433: a rotating shaft; 440: a belt.

Detailed Description

So that the manner in which the features and techniques of the disclosed embodiments can be understood in more detail, a more particular description of the embodiments of the disclosure, briefly summarized below, may be had by reference to the appended drawings, which are not intended to be limiting of the embodiments of the disclosure. In the following description of the technology, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may still be practiced without these details. In other instances, well-known structures and devices may be shown simplified in order to simplify the drawing.

The terms first, second and the like in the description and in the claims of the embodiments of the disclosure and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe embodiments of the present disclosure. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

In the embodiments of the present disclosure, the terms "upper", "lower", "inner", "middle", "outer", "front", "rear", and the like indicate an azimuth or a positional relationship based on that shown in the drawings. These terms are used primarily to better describe embodiments of the present disclosure and embodiments thereof and are not intended to limit the indicated device, element, or component to a particular orientation or to be constructed and operated in a particular orientation. Also, some of the terms described above may be used to indicate other meanings in addition to orientation or positional relationships, for example, the term "upper" may also be used to indicate some sort of attachment or connection in some cases. The specific meaning of these terms in the embodiments of the present disclosure will be understood by those of ordinary skill in the art in view of the specific circumstances.

In addition, the terms "disposed," "connected," "secured" and "affixed" are to be construed broadly. For example, "connected" may be in a fixed connection, a removable connection, or a unitary construction; may be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements, or components. The specific meaning of the above terms in the embodiments of the present disclosure may be understood by those of ordinary skill in the art according to specific circumstances.

The term "plurality" means two or more, unless otherwise indicated.

In the embodiment of the present disclosure, the character "/" indicates that the front and rear objects are an or relationship. For example, A/B represents: a or B.

The term "and/or" is an associative relationship that describes an object, meaning that there may be three relationships. For example, a and/or B, represent: a or B, or, A and B.

It should be noted that, without conflict, the embodiments of the present disclosure and features of the embodiments may be combined with each other.

Referring to fig. 1-6, an embodiment of the present disclosure provides a screw thread drawing device for an injection mold, including a bracket 100, a nut 210, a screw 220, a driving motor 200, and a torque limiter, wherein the bracket 100 is fixed in position with respect to the injection mold; a nut 210 disposed on the bracket 100; a screw 220 rotatably penetrating the nut 210, the screw 220 being bidirectionally moved along an axial direction thereof when bidirectionally rotated; the driving motor 200 is arranged on the bracket 100 and is connected with the screw 220 through a transmission mechanism in a transmission way; the torque limiter is arranged on the transmission mechanism.

The mould is provided with an inner cavity with a certain shape, and the injection molding material is injected into the mould to be shaped to be matched with the inner cavity of the mould, so that the injection molding product is formed. The screw, i.e., the molding insert, is threaded into the cavity of the mold prior to injection of the injection molding material, which is shaped and threaded out of the screw 220 to construct an internal thread in the injection molded product.

The screw thread drawing device for the injection mold can be integrated with the mold, and can be in a split form with the mold, and the screw thread drawing device and the mold are required to be fixed respectively or connected into a whole before injection molding during split setting.

The screw-threaded device comprises a bracket 100, the bracket 100 being adapted to secure the screw-threaded device and to provide a mounting location for the rest of the screw-threaded device.

The nut 210 is fixed to the bracket 100, and the screw 220 penetrates the nut 210 and is engaged with the nut 210. When the screw 220 rotates, the screw 220 moves in the axial direction of the screw 220 with respect to the bracket 100. Specifically, when the screw 220 is rotated in the first direction, it moves toward the cavity of the mold to penetrate into the interior of the mold; when the screw 220 is rotated in the second direction, it moves away from the cavity of the mold, thereby completing demolding. The driving motor 200 is provided to the bracket 100 and is connected to the screw 220 through a transmission mechanism. The screw 220 is driven to bidirectionally rotate by the bidirectional rotation of the driving motor 200. The transmission mechanism is provided with a torque limiter, specifically, the torque limiter includes a drive side and a load side, and the drive side and the load side are disconnected when the driving force exceeds a preset load value. In the case where the rotational resistance of the screw 220 is large, the torque limiter can prevent damage to the threads or breakage of the screw due to the excessive rotational resistance of the screw 220.

By using the thread drawing device provided by the embodiment of the disclosure, the torque of the screw 220 can be effectively limited by the torque limiter, so that thread damage or screw breakage can be avoided under the condition that the adhesion force between the screw 220 and an injection molding material is large.

Optionally, the transmission mechanism includes a first transmission gear 410 and a second transmission gear 420, where the first transmission gear 410 is sleeved on the output shaft of the driving motor and rotates together with the output shaft of the driving motor; the second transmission gear 420 is sleeved on the screw 220 and rotates along with the screw 220, and the second transmission gear 420 is in transmission connection with the first transmission gear 410.

The first transmission gear 410 is fixed to an output shaft of the driving motor, and when the driving motor 200 rotates, the first transmission gear 410 rotates coaxially with the output shaft of the driving motor. The second driving gear is fixed to the screw 220, and the second driving gear rotates coaxially with the screw 220. This form of gear engagement facilitates controlling the angle of rotation of the screw 220 and thus the distance of axial movement of the screw 220 along the screw 220. Specifically, in the case of a certain transmission ratio, the number of turns or the angle of rotation of the screw 220 can be controlled by controlling the number of turns or the angle of rotation of the output shaft of the motor.

Alternatively, the driving motor 200 is a stepping motor.

The rotation angle can be precisely controlled by the stepper motor, and the accuracy of the movement of the control screw 220 can be further improved by the stepper motor.

Optionally, the transmission mechanism further includes a speed reducing structure, the input end is in driving connection with the first transmission gear 410, and the output end is in driving connection with the second transmission gear 420.

A reduction structure is provided, and a driving motor using a smaller power can provide a larger torque for the rotation of the screw 220. The use of a lower power drive motor reduces the cost and size of the screw-down device. In addition, be provided with the speed reducing structure, the speed reducing structure realizes the transmission between driving motor 200 and the screw 220, and driving motor need not set up in the position that is close to the screw, has made things convenient for driving motor's setting.

Alternatively, the output shaft of the drive motor is parallel to the screw 220, and the output shaft of the drive motor faces the unscrewing direction of the screw 220.

The output shaft of the driving motor faces the unscrewing direction of the screw 220 with the first driving gear as a parting line, i.e., the body of the driving motor 200 is located at the same side as the mold. The size of the die is larger along the length direction of the screw 220, and the driving motor 200 is also arranged along the length direction of the screw 220, so that the integrated arrangement of the screw thread drawing device and the die is facilitated, and the integral volume of the screw thread drawing device and the die can be reduced.

Alternatively, the speed reducing structure includes a rotating shaft 433, a first speed reducing gear 431 and a second speed reducing gear 432, wherein the rotating shaft 433 is rotatably disposed on the bracket 100 and parallel to the screw 220; the first reduction gear 431 is arranged on the rotating shaft 433 and is in transmission connection with the first transmission gear 410; the second reduction gear 432 is disposed on the rotating shaft 433 and rotates together with the rotation, and the second reduction gear 432 is engaged with the second transmission gear 420.

The rotation shaft 433 is parallel to the output shaft of the driving motor and the screw 220. The first reduction gear 431 and the second reduction gear 432 each rotate with the rotation shaft 433. The first transmission gear 410 is in transmission connection with the first reduction gear 431, and when the driving motor 200 rotates, the first transmission gear 410 drives the first reduction gear 431 to rotate, thereby driving the rotating shaft 433 to rotate. The second reduction gear 432 is meshed with the second transmission gear 420, and when rotating, the second reduction gear 432 is driven to rotate, so that the second transmission gear 420 is driven to rotate, and further, the screw 220 is driven to rotate. The diameter of the first reduction gear 431 is larger than the diameter of the second reduction gear 432, the angular speed of the first reduction gear 431 is the same as that of the second reduction gear 432, and the linear speed of the first reduction gear 431 is larger than that of the second reduction gear 432. The first transmission gear 410 rotates by a larger angle and the second transmission gear 420 rotates by a smaller angle, which increases the torque force to the screw 220 on the one hand and facilitates more accurate control of the rotation of the screw 220 on the other hand. The first reduction gear 431 and the second reduction gear 432 are fixed on the rotating shaft 433, and the structure is simple and the operation is reliable.

Alternatively, the thickness of the second reduction gear 432 is greater than the thickness of the second transmission gear 420, and the second transmission gear 420 is always meshed with the second reduction gear 432 when moving in the axial direction of the screw 220.

The second transmission gear 420 fixed to the screw 220 moves along the axial direction of the screw 220 as the screw 220 rotates. The relative position to the rotating shaft 433 remains unchanged when the second reduction gear 432 rotates. The thickness of the second reduction gear 432 is greater than that of the second transmission gear 420, and the second transmission gear can always remain engaged with the second reduction gear 432 even if it moves in the axial direction of the screw 220. With such an arrangement, a reliable transmission between the screw 220 and the driving motor 200 can be ensured in the case where the linear movement distance of the screw 220 is large.

Alternatively, the thickness of the second transmission gear 420 is greater than the thickness of the second reduction gear 432, and the second transmission gear 420 is always meshed with the second reduction gear 432 while moving in the axial direction of the screw 220.

The second transmission gear 420 fixed to the screw 220 moves along the axial direction of the screw 220 as the screw 220 rotates along the axial direction of the screw 220. The relative position to the rotating shaft 433 remains unchanged when the second reduction gear 432 rotates. The thickness of the second transmission gear 420 is greater than that of the second reduction gear 432, and the second transmission gear is always maintained in engagement with the second reduction gear 432 even if it moves in the axial direction of the screw 220. With such an arrangement, a reliable transmission between the screw 220 and the driving motor 200 can be ensured in the case where the linear movement distance of the screw 220 is large.

Optionally, the transmission mechanism further includes a belt 440 provided with tooth grooves, and the first reduction gear 431 is in transmission connection with the first transmission gear 410 through the belt 440.

Belt 440 is toothed with a gear engaged by the toothed slot. Specifically, the belt 440 is sleeved on the first reduction gear 431 and the first transmission gear 410 and is engaged with the first reduction gear 431 and the first transmission gear 410 through tooth grooves. When the driving motor 200 rotates, the first transmission gear 410 drives the first reduction gear 431 to rotate through the belt 440. By adopting a belt transmission mode, a part of impact load can be absorbed through the belt, so that the screw fracture caused by overlarge instant impact force applied to the driving motor or the screw is avoided. The toothed grooves formed in the belt 440 can also make the belt 440 drive mode have the drive proportion, which is beneficial to accurately controlling the movement of the screw 220.

Optionally, the torque limiter includes a first torque limiter 310 disposed between an output shaft of the driving motor and the first transmission gear 410.

A first torque limiter 310 is provided between an output shaft of the drive motor and the first transmission gear 410, the output shaft of the drive motor is connected to a driving side of the first torque limiter 310, and the first transmission gear 410 is connected to a load side of the first torque limiter 310. Whether the rotation resistance of the screw 220 is too large or the speed reducing structure is blocked, the first torque limiter 310 can be timely disconnected, so that the too high current of the driving motor 200 is avoided, and the breakage or the thread damage of the screw 220 is also avoided.

Optionally, the torque limiter further includes a second torque limiter 320 disposed between the second transmission gear 420 and the screw 220.

A second torque limiter 320 is provided between the second transmission gear 420 and the screw 220, the screw 220 is connected to the driving side of the second torque limiter 320, and the second transmission gear 420 is connected to the load side of the first torque limiter 310. Although the second drive gear 420 serves as a drive for the movement of the screw 220. The connection of the screw 220 to the driving side of the second torque limiter 320 not only can also serve as a torque limiter, but also facilitates the installation and placement of the second torque limiter 320. The second torque limiter 320 is provided, and in case that the rotation resistance of the second driving screw 220 is too large, the second torque limiter 320 can be timely disconnected, thereby avoiding breakage or thread damage of the screw 220. In the case that the first torque limiter 310 and the second torque limiter 320 are simultaneously provided, the torque limiting function can be achieved at both the screw rod 220 end and the driving motor 200 end, the driving motor 200 and the screw rod 220 are protected, and the use reliability of the screw thread drawing device is improved.

Optionally, the screw thread extracting device further includes a first limiting table 140 fixed to the bracket 100, and when the screw 220 moves to the first position in the first direction, a first surface of the second transmission gear 420 abuts against the first limiting table 140.

The screw moves linearly between a first position and a second position, which are extreme positions in both directions when the screw moves. The first limiting stage 140 is used for mechanically limiting the linear motion of the screw 220. The screw 220 extends into the mold when moving in the first direction, and when moving to the first position, the first surface of the second transmission gear 420 abuts against the first limiting table 140. This effectively controls the depth of penetration of the screw 220, further facilitating control of the depth of the internal threads of the injection molded product.

Optionally, the screw thread extracting device further includes a first proximity switch that is triggered when the screw 220 moves to the first position in the first direction, and a control part configured to control the driving motor 200 to stop rotating if the first proximity switch is triggered.

This allows for automatic control of the insertion of the screw 220 and prevents the screw 220 from continuing to rotate after it has moved into place.

Optionally, the first face of the second drive gear 420 or the first stop 140 is lined with an elastomeric material.

When the second transmission gear 420 is abutted against the first limiting platform 140, the elastic material can absorb impact energy, so that the screw thread drawing device is prevented from deforming due to impact. In addition, the elastic material may linearly increase the load of the driving motor 200, thereby allowing a reaction time for the first moment limiter 310 or the second moment limiter 320, which is advantageous for smooth operation of the screw thread drawing device.

Optionally, the screw thread extracting device further includes a second limiting table 150, fixed on the bracket 100, and when the screw 220 moves to the second position in the second direction, the second face of the second transmission gear abuts against the second limiting table 150.

The second limiting stage 150 is used for mechanically limiting the linear motion of the screw 220. The screw 220 protrudes from the mold to complete demolding when moving in the second direction, and the second face of the second transmission gear 420 abuts against the second limit table 150 when the screw 220 moves in the second direction to the second position. The extension length of the screw 220 can be effectively controlled, and the screw drawing device is further convenient for controlling the demolding of the screw 220.

Optionally, the screw thread extracting device further includes a second proximity switch, the second proximity switch is triggered when the screw 220 moves to the farthest position in the second direction, and the control part is configured to control the driving motor 200 to stop rotating if the second proximity switch is triggered.

This allows for automatic control of the demolding of the screw 220 and avoids the continued rotation of the drive motor 200 when the screw 220 is in place.

Optionally, the second face of the second drive gear 420 or the second stop 150 is lined with an elastomeric material.

When the second transmission gear 420 abuts against the second limiting platform 150, the elastic material can absorb impact energy, so that the screw thread drawing device is prevented from deforming due to impact. In addition, the elastic material may linearly increase the load of the driving motor, thereby allowing a reaction time for the first moment limiter 310 or the second moment limiter 320, which is advantageous for smooth operation of the screw thread drawing device.

Optionally, the bracket 100 includes a first substrate 110 and a second substrate 120, where the first substrate 110 and the second substrate 120 form an interlayer, and the first transmission gear 410 and the second transmission gear 420 are located in the interlayer.

The first base plate 110 serves as a bottom plate of the screw-thread drawing device, and the second base plate 120 serves as a mounting plate of the screw-thread drawing device. The nut 210 is fixed on the second base plate 120, the second base plate 120 is provided with a through hole, and the screw 220 penetrates into the nut 210 through the through hole. With such arrangement, when the driving motor 200 is driven, the moving part is located in the interlayer, so that the safety of the screw thread drawing device in use can be improved.

Optionally, the deceleration structure is located within the interlayer.

With this arrangement, the belt 440, the first transmission gear 410 and the second transmission gear 420 are all positioned in the interlayer, which can further improve the safety of the screw thread drawing device in use.

Optionally, the stand 100 further includes a motor fixing plate fixed to the first substrate 110 or the second substrate 120, and the driving motor 200 is fixed to the motor fixing plate.

With such a configuration, the configuration of the driving motor 200 is facilitated.

The above description and the drawings illustrate embodiments of the disclosure sufficiently to enable those skilled in the art to practice them. Other embodiments may include structural and other modifications. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in, or substituted for, those of others. The embodiments of the present disclosure are not limited to the structures that have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims (10)

1. A thread drawing apparatus for an injection mold, comprising:

the bracket is fixed relative to the injection mold;

the nut is arranged on the bracket;

the screw rod can penetrate the nut in a rotating way, and can move in the axial direction of the screw rod in a two-way when rotating in the two-way;

the driving motor is arranged on the bracket and is connected with the screw rod through a transmission mechanism in a transmission way;

the torque limiter is arranged on the transmission mechanism.

2. The thread extraction device of claim 1, wherein the transmission mechanism comprises:

the first transmission gear is sleeved on the output shaft of the driving motor and rotates along with the output shaft of the driving motor;

the second transmission gear is sleeved on the screw and rotates along with the screw, and is in transmission connection with the first transmission gear.

3. The thread extraction device of claim 2, wherein the transmission mechanism further comprises:

and the input end of the speed reducing structure is in transmission connection with the first transmission gear, and the output end of the speed reducing structure is in transmission connection with the second transmission gear.

4. A thread extraction device according to claim 3 wherein the speed reduction structure comprises:

the rotating shaft is rotatably arranged on the bracket and is parallel to the screw rod;

the first reduction gear is arranged on the rotating shaft and is in transmission connection with the first transmission gear;

the second speed reducing gear is arranged on the rotating shaft and rotates along with the rotating shaft, and the second speed reducing gear is meshed with the second transmission gear.

5. The thread-drawing device of claim 4, wherein the thread-drawing means comprises a thread-drawing means,

the thickness of the second reduction gear is larger than that of the second transmission gear, and the second transmission gear is always meshed with the second reduction gear when moving along the axial direction of the screw rod.

6. The thread extraction device of claim 4, wherein the transmission mechanism further comprises:

and the belt is provided with tooth grooves, and the first reduction gear is in transmission connection with the first transmission gear through the belt.

7. The thread-extracting apparatus of claim 2, wherein the torque limiter comprises:

the first torque limiter is arranged between the output shaft of the driving motor and the first transmission gear.

8. The thread-extracting apparatus of claim 7, wherein the torque limiter further comprises:

the second torque limiter is arranged between the second transmission gear and the screw rod.

9. The thread extraction device according to any one of claims 2 to 8, further comprising:

the first limiting table is fixed on the support, and when the screw moves to a first position in a first direction, the first surface of the second transmission gear is abutted to the first limiting table.

10. The thread extraction device of claim 9, further comprising:

the second limiting table is fixed on the support, and when the screw rod moves to a second position in a second direction, the second face of the second transmission gear is abutted to the second limiting table.