A compact injection molding machine with a transfer device

Abstract

The present application relates to the technical field of the whole moving structure of small injection molding machine, solve the problem of uneven stress and nozzle adjustment by oblique force in the prior art of the whole moving structure of small injection molding machine, and specifically disclose a whole moving device of small injection molding machine, the injection molding machine is provided with a head plate and an integral injection seat, wherein the integral injection seat is provided with a nozzle, the head plate is provided with a pouring gate, the whole moving device comprises a lead screw transmission assembly, a connecting assembly and a driving assembly, the lead screw transmission assembly comprises two lead screws which are symmetrically arranged on both sides of the integral injection seat, the driving assembly drives the two lead screws to rotate synchronously, ensures that the stress on both sides of the head plate is uniform, prevents the nozzle on the injection seat from being subjected to oblique torque, and the connecting assembly comprises a connecting rod which is used for connecting the lead screw and the head plate, when the position of the nozzle is adjusted, the connecting rod can adjust the position of the connecting assembly and the injection seat, the resistance of the nozzle movement can be eliminated, and the nozzle adjustment is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of injection molding machine whole moving device, in particular to a small injection molding machine whole moving device. BACKGROUND

[0002] In the prior art, the injection molding machine whole moving device is generally divided into two kinds, one of which is a single lead screw whole moving structure, which is more common. The single lead screw is connected to one side of the head plate, and the other side of the head plate is not stressed, resulting in the inclination of the head plate and the defects of injection and product forming. The other is a double lead screw whole moving structure, but it is generally used for injection molding machines with three-plate structure injection seats. It is not used for small injection molding machines with integrated injection seats, such as patent No. 2011205194382 and patent name injection molding machine double lead screw focus symmetrical guide nozzle contact device. The double lead screw whole moving structure is disclosed, which installs the motor at the front end of the injection seat and uses the double lead screw to abut against both sides of the head plate to make the stress uniform. However, it is only suitable for injection molding machines with three-plate structure injection seats, i.e. only suitable for medium and large injection molding machines. Otherwise, the motor and its transmission assembly will interfere with the lead screw. In addition, it is highly affected by the assembly accuracy of the lead screw. Once the assembly accuracy of the lead screw is wrong, the nozzle position needs to be adjusted. At this time, the injection seat is not moving, which often causes the injection seat to provide an inclined force to the nozzle, resulting in a resistance to the nozzle. Additional power devices are needed to adjust the position of the nozzle. The nozzle adjustment is troublesome, and even the injection accuracy may be affected. SUMMARY

[0003] The present application takes into account the foregoing problems and is made. The purpose of the application is to provide a small injection molding machine whole moving device, which is suitable for small injection molding machines and can fine-tune the injection seat in the up-down and left-right directions, avoid the nozzle being adjusted by an inclined force, facilitate the adjustment of the nozzle position, and improve the injection accuracy of the nozzle.

[0004] To achieve the above-mentioned purpose, the present application provides a small injection molding machine whole moving device, which is provided with a head plate and an integrated injection seat on the injection molding machine. The integrated injection seat is provided with a nozzle, and the head plate is provided with an inlet. The whole moving device comprises:

[0005] A lead screw transmission assembly, which comprises two lead screws symmetrically arranged on both sides of the integrated injection seat. Both lead screws are connected to the integrated injection seat, and the middle part of the lead screw is engaged with a fixed part.

[0006] A connecting assembly, which comprises two connecting rods and a compression spring. The connecting rod corresponds to the lead screw one by one. One end of the connecting rod is connected to one end of the corresponding lead screw through a connecting sleeve. The other end of the connecting rod is connected to both sides of the head plate through the compression spring.

[0007] The drive assembly is located at the tail end of the integrated injection seat and can drive the two lead screws to rotate synchronously.

[0008] When the center of the nozzle is adjusted to align with the center of the inlet, the connecting rod can move in the up-down and left-right directions to drive the integrated injection seat to move to the position corresponding to the nozzle.

[0009] According to the above-described small injection molding machine's transfer device, the connecting rod includes a transfer connecting rod and a spring connecting rod, and the connecting sleeve is located at the end of the lead screw away from the integrated injection seat; one end of the transfer connecting rod is inserted into the connecting sleeve and threadedly connected to the connecting sleeve, and the other end of the transfer connecting rod is rotatably connected to the spring connecting rod.

[0010] The compression spring is sleeved on the spring connecting rod, and the spring connecting rod is movably connected to the head plate through an anti-rotation block.

[0011] According to the above-described small injection molding machine transfer device, the spring connecting rod is provided with a first positioning hole at one end near the transfer connecting rod, one end of the transfer connecting rod is inserted into the first positioning hole, and the transfer connecting rod is connected to the front and rear sides of the first positioning hole through a rotating pin.

[0012] A gap is provided between the upper surface of the adjusting connecting rod and the top surface of the first positioning hole, and a gap is provided between the lower surface of the adjusting connecting rod and the bottom surface of the first positioning hole.

[0013] According to the above-described small injection molding machine transfer device, the anti-rotation block is fixed on the head plate, and the anti-rotation block is provided with a second positioning hole arranged in the left and right direction. One end of the spring connecting rod is provided with a protrusion, and the protrusion is movably locked in the second positioning hole.

[0014] There are gaps between the left and right sides of the protrusion and the second positioning hole.

[0015] According to the above-described small injection molding machine transfer device, the connecting assembly further includes a connecting block, the connecting block is fixed on both sides of the head plate, and the connecting block is provided with a mounting hole, the anti-rotation block is disposed in the mounting hole, and the end of the spring connecting rod that is connected to the anti-rotation block is located in the mounting hole;

[0016] The spring connecting rod is provided with a first limiting part, and the connecting block is provided with a second limiting part, wherein the second limiting part is located on the side of the first limiting part away from the head plate, and the compression spring is located between the first limiting part and the second limiting part.

[0017] According to the above-described small injection molding machine transfer device, the spring connecting rod is provided with a limiting groove, and the side wall of the limiting groove near the head plate constitutes the first limiting part; the connecting block is provided with a connecting plate, and the two ends of the connecting plate are respectively provided with an upward first limiting plate and a downward second limiting plate, and the top of the mounting hole is provided with a downward third limiting plate, wherein...

[0018] The first limiting plate can abut against the third limiting plate, the second limiting plate constitutes the second limiting part, and the second limiting plate can be inserted into the limiting groove. One end of the compression spring is connected to the side wall of the limiting groove, and the other end of the compression spring is connected to the second limiting plate.

[0019] The above-described small injection molding machine transfer device further includes a photoelectric sensor, which is mounted on the connecting block and is used to monitor the compression amount of the compression spring.

[0020] The photoelectric sensor is electrically connected to the alarm unit of the injection molding machine.

[0021] According to the above-described small injection molding machine transfer device, the drive assembly includes a drive motor and a transmission wheel set arranged on both sides of the integrated injection seat. The drive motor is fixed to the tail end of the integrated injection seat. The transmission wheel set includes a motor pulley and two lead screw pulleys. The motor pulley is connected to the output shaft of the drive motor. The two lead screw pulleys are respectively connected to the lead screw. A synchronous belt is provided between the motor pulley and the two lead screw pulleys.

[0022] According to the above-described small injection molding machine transfer device, the transmission wheel set further includes a tension wheel and two intermediate wheels, the two intermediate wheels being located between the two lead screw pulleys, and the tension wheel being located between the motor pulley and the lead screw pulley.

[0023] According to the above-described small injection molding machine's transfer device, the fixing component is a nut.

[0024] The present invention has the following beneficial effects:

[0025] 1. The connecting rod used to connect the lead screw can move in the up and down and left and right directions. When adjusting the nozzle due to assembly errors, the injection seat can be adjusted to adapt to the direction so that the nozzle is not subjected to oblique force, which facilitates nozzle adjustment and ensures injection accuracy.

[0026] 2. Dual lead screw drive ensures uniform force distribution on both sides of the head plate, resulting in uniform nozzle contact force and no bending torque;

[0027] 3. By placing the drive assembly at the rear end of the integrated injection unit, interference caused by placing the drive assembly at the front end of the injection unit in small injection molding machines can be avoided, making assembly easier.

[0028] 4. A photoelectric sensor is installed in the connecting block. The photoelectric sensor can monitor the compression amount of the compression spring caused by the contact force of the nozzle. A compression amount can be preset. If the compression amount is exceeded, the sensor can send a message to the alarm unit of the injection molding machine to improve the safety performance of the injection molding machine.

[0029] 5. The timing belt and pulley can drive the two lead screws to rotate synchronously, achieving synchronous drive of the two lead screws, and the tension of the timing belt can be adjusted by the tension wheel. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 This is a cross-sectional view of the overall structure of the present invention;

[0032] Figure 3 yes Figure 2 A magnified structural diagram at point A;

[0033] Figure 4 This is a schematic diagram of the drive component structure of the present invention;

[0034] In the diagram: 100, lead screw drive assembly; 110, lead screw; 120, lead screw nut; 200, connecting assembly; 210, connecting rod; 211, adjusting connecting rod; 211a, rotating pin; 212, spring connecting rod; 212a, limiting groove; 220, compression spring; 230, connecting sleeve; 240, anti-rotation block; 250, connecting block; 251, connecting plate; 300, drive assembly; 310, drive motor; 320, motor pulley; 330, lead screw pulley; 340, tensioning wheel; 350, intermediate wheel; 400, photoelectric sensor; 500, head plate; 600, integrated injection seat. Detailed Implementation

[0035] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solution of the present invention. However, the invention is not limited to these embodiments.

[0036] like Figures 1-4 As shown, a moving device for a small injection molding machine is disclosed. The injection molding machine is equipped with a head plate 500 and an integrated injection seat 600. The integrated injection seat 600 is equipped with a nozzle, and the head plate 500 is equipped with a sprue. During injection, the injection seat 600 moves towards the side closer to the head plate 500 until the nozzle presses against the sprue, and the injection action is performed through the sprue. The moving device includes:

[0037] The lead screw drive assembly 100 includes two lead screws 110 symmetrically arranged on both sides of the integrated injection seat 600. Both lead screws 110 are connected to the integrated injection seat 600, and the middle part of the lead screw 110 is engaged with a fixed member. The fixed member is stationary. Once the lead screw 110 rotates, due to its engagement, the lead screw 110 will move in the left and right direction, and drive the integrated injection seat 600 to move in the left and right direction, that is, the forward and backward movement of the injection seat 600.

[0038] In this embodiment, the two lead screws 110 are symmetrical about the center of the integrated injection seat 600.

[0039] The connecting assembly 200 includes two connecting rods 210 and a compression spring 220. Each connecting rod 210 corresponds to a lead screw 110. One end of each connecting rod 210 is connected to one end of the corresponding lead screw 110 via a connecting sleeve 230. The other ends of each connecting rod 210 are connected to both sides of the head plate 500 via the compression spring 220. The connecting rods 210 and the connecting sleeve 230 provide a movable support for the lead screw 110. The compression spring 220 can detect the magnitude of the nozzle contact force.

[0040] The drive assembly 300 is located at the tail end of the integrated injection seat 600 and can drive the two lead screws 110 to rotate synchronously. The two lead screws 110 rotate synchronously and together drive the injection seat 600 to perform forward and backward movements. The injection seat 600 is driven by two lead screws 110 and is connected to the opposite sides of the head plate 500 through a double connecting rod, so that the force on both sides of the head plate 500 is more uniform and the nozzle is not subjected to bending torque, resulting in better injection effect.

[0041] When the center of the nozzle is adjusted to align with the center of the inlet, the connecting rod can move in the up-down and left-right directions to drive the integrated injection seat to move to the position corresponding to the nozzle.

[0042] When the center of the nozzle is adjusted to align with the center of the inlet, the connecting rod 210 can move in the up-down and left-right directions to drive the integrated injection seat to move to the position corresponding to the nozzle. When the nozzle position is adjusted to align with the center of the inlet, the nozzle is subjected to an oblique force because the integrated injection seat has not moved. The nozzle needs an additional force to overcome this oblique force to facilitate nozzle adjustment. The connecting rod 210 drives the injection seat 600, that is, adjusts the position of the injection seat 600 to align with the nozzle. At this time, the nozzle is no longer subjected to force. With the help of the double screw drive structure, the force on the nozzle is more uniform and free from oblique force, which not only facilitates nozzle adjustment but also ensures injection accuracy.

[0043] The connecting rod 210 includes a shifting connecting rod 211 and a spring connecting rod 212. The connecting sleeve 230 is located at the end of the lead screw 110 away from the integrated injection seat 600. One end of the shifting connecting rod 211 is inserted into the connecting sleeve 230 and threadedly connected to the connecting sleeve 230. The other end of the shifting connecting rod 211 is rotatably connected to the spring connecting rod 212. The connecting sleeve 230 is fixedly connected to the lead screw 110, that is, the connecting sleeve 230 rotates together with the rotation of the lead screw 110. The rotation of the lead screw 110 is transformed into horizontal lateral movement on the shifting connecting rod 211 through the threaded connection, that is, left and right movement.

[0044] A compression spring 220 is sleeved on a spring connecting rod 212, and the spring connecting rod 212 is movably connected to the head plate 500 through an anti-rotation block 240.

[0045] A first positioning hole is provided on one end of the spring connecting rod 212 near the adjusting connecting rod 211. One end of the adjusting connecting rod 211 is inserted into the first positioning hole, and the adjusting connecting rod 211 is connected to the front and rear sides of the first positioning hole through a rotating pin 211a. There is a gap between the upper surface of the adjusting connecting rod 211 and the top surface of the first positioning hole, and there is a gap between the lower surface of the adjusting connecting rod 211 and the bottom surface of the first positioning hole. The adjusting connecting rod 211 can rotate through the rotating pin 211a. The rotating pin 211a is connected to the front and rear sides of the first positioning hole, which limits the freedom of the adjusting connecting rod 211 in the front-back and left-right directions, so that it can only rotate in the up-down direction relative to the spring connecting rod 212. The gap between the upper and lower surfaces of the adjusting connecting rod 211 and the positioning hole provides reserved space for the adjusting connecting rod 211 to rotate up and down.

[0046] The anti-rotation block 240 is fixed on the head plate 500, and the anti-rotation block 240 is provided with a second positioning hole arranged in the left and right direction. One end of the spring connecting rod 212 is provided with a protrusion, which is movably locked in the second positioning hole. There are gaps between the left and right sides of the protrusion and the second positioning hole. The second positioning hole is used to restrict the rotation of the spring connecting rod 212. The second positioning hole can be set as a square hole, and the protrusion can be set as a square shape. When the protrusion is inserted into the second positioning hole, the protrusion can only move horizontally left and right along the second positioning hole. The gap between the protrusion and the second positioning hole is used to allow the protrusion to move to the left and right. In this embodiment, the spring connecting rod 212 has a degree of freedom in the horizontal left and right direction, while the adjusting connecting rod 211 has a degree of freedom in the vertical direction and can drive the injection seat 600 to make fine adjustments along these four degrees of freedom to ensure that the center of the nozzle on the injection seat 600 is aligned with the center of the inlet.

[0047] The connecting assembly 200 further includes a connecting block 250, which is fixed to both sides of the head plate 500. The connecting block 250 has a mounting hole, and an anti-rotation block 240 is disposed within the mounting hole. One end of the spring connecting rod 212 that connects to the anti-rotation block 240 is located within the mounting hole. The spring connecting rod 212 has a first limiting portion, and the connecting block 250 has a second limiting portion. The second limiting portion is located on the side of the first limiting portion away from the head plate 500. The compression spring 220 is located at the first limiting portion. In the initial state, the compression spring 220 is already in a compressed state between the first limiting part and the second limiting part. This state is defined as the first mounting state. When the mold is closed, the nozzle will squeeze the head plate 500, and the head plate 500 will provide a reaction force to the nozzle. The nozzle is then subjected to a contact force, which drives the injection seat 600 to move to the left. At this time, the transfer linkage 211 and the spring linkage 212 move to the left together, and the first limiting part will further squeeze the compression spring 220. The nozzle contact force can be determined based on the difference in compression.

[0048] Furthermore, the spring connecting rod 212 is provided with a limiting groove 212a, and the side wall of the limiting groove 212a near the head plate 500 constitutes the first limiting part; the connecting block 250 is provided with a connecting plate 251, and the two ends of the connecting plate 251 are respectively provided with an upward first limiting plate and a downward second limiting plate, and the top of the mounting hole is provided with a downward third limiting plate, wherein the first limiting plate can abut against the third limiting plate, the second limiting plate constitutes the second limiting part, and the second limiting plate can be inserted into the limiting groove 212a, one end of the compression spring 220 is connected to the side wall of the limiting groove 212a, and the other end of the compression spring 220 is connected to the second limiting plate.

[0049] It also includes a photoelectric sensor 400, which is mounted on the connecting block 250. The photoelectric sensor 400 is used to monitor the compression amount of the compression spring 220. The photoelectric sensor 400 is electrically connected to the alarm unit of the injection molding machine. It can preset a compression amount of the compression spring 220 according to the safe range of the nozzle contact force. This preset compression amount is greater than the compression amount of the compression spring 220 in the first state. If the photoelectric sensor 400 detects that the compression amount reaches this value, it will issue an alarm through the alarm unit of the injection molding machine to realize real-time safety monitoring of the nozzle contact force.

[0050] The drive assembly 300 includes a drive motor 310 and a transmission wheel set arranged on both sides of the integrated injection seat 600. The drive motor 310 is fixed to the tail end of the integrated injection seat 600. The transmission wheel set includes a motor pulley 320 and two lead screw pulleys 330. The motor pulley 320 is connected to the output shaft of the drive motor 310, and the two lead screw pulleys 330 are respectively connected to the lead screws 110. A synchronous belt is provided between the motor pulley 320 and the two lead screw pulleys 330. The output shaft of the drive motor 310 drives the motor pulley 320 to rotate, and the pulley drives the two lead screws 110 to rotate synchronously through the synchronous belt, thereby driving the two lead screws 110 to rotate synchronously.

[0051] The transmission pulley set also includes a tensioning pulley 340 and two intermediate pulleys 350. The two intermediate pulleys 350 are located between the two lead screw pulleys 330, and the tensioning pulley 340 is located between the motor pulley 320 and the lead screw pulley 330. The intermediate pulleys 350 are used to arrange the synchronous belt and prevent the synchronous belt from interfering with other components. The position of the tensioning pulley 340 is adjustable and is used to tighten the synchronous belt.

[0052] The fixing component is set as nut 120, which is fixed on other components. During the whole process, nut 120 remains stationary. When screw 110 rotates, it engages with nut 120, and screw 110 moves horizontally through connecting sleeve 230 to facilitate the positioning of nut 120.

[0053] The technical solution of the present invention has been described in detail above with reference to the accompanying drawings. The described embodiments are used to help understand the concept of the present invention. The specific embodiments described herein are merely illustrative examples of the spirit of the present invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

[0054] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0055] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0056] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0057] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A transfer device for a small injection molding machine, said injection molding machine being provided with a head plate and an integrated injection seat, said integrated injection seat being provided with a nozzle, said head plate being provided with a sprue, characterized in that, The whole moving device comprises: a screw transmission assembly, which comprises two screws symmetrically arranged on both sides of the integrated injection seat, both of the screws are connected with the integrated injection seat, and the middle part of the screw is engaged with a fixing member; a connecting assembly, which comprises two connecting rods and a compression spring, the connecting rods correspond to the screws one by one, one end of each connecting rod is connected with one end of the corresponding screw through a connecting sleeve, and the other end of each connecting rod is connected with the two sides of the head plate through the compression spring; a driving assembly, which is arranged at the tail end of the integrated injection seat and can drive the two screws to rotate synchronously; when the center of the nozzle is adjusted to be aligned with the center of the pouring gate, the connecting rods can move in the up-down and left-right directions to drive the integrated injection seat to move to the position corresponding to the nozzle; the connecting rods comprise whole moving connecting rods and spring connecting rods, the connecting sleeve is arranged at the end of the screw away from the integrated injection seat, one end of the whole moving connecting rod is inserted into the connecting sleeve and is threadedly connected with the connecting sleeve, and the other end of the whole moving connecting rod is rotatably connected with the spring connecting rod; the compression spring sleeve is arranged on the spring connecting rod, and the spring connecting rod is movably connected with the head plate through an anti-rotation block; a first positioning hole is arranged on the end of the spring connecting rod close to the whole moving connecting rod, one end of the whole moving connecting rod is inserted into the first positioning hole, and the whole moving connecting rod is connected with the front and back sides of the first positioning hole through a rotating pin; a gap is arranged between the upper surface of the whole moving connecting rod and the top surface of the first positioning hole, and a gap is arranged between the lower surface of the whole moving connecting rod and the bottom surface of the first positioning hole, so that the whole moving connecting rod can move in the up-down direction; the anti-rotation block is fixed on the head plate, a second positioning hole is arranged on the anti-rotation block in the left-right direction, a protrusion is arranged on one end of the spring connecting rod, and the protrusion is movably clamped in the second positioning hole; a gap is arranged between the left and right sides of the protrusion and the second positioning hole; the second positioning hole is arranged in the form of a square hole, and the protrusion is arranged in the form of a square, and when the protrusion is inserted into the second positioning hole, the protrusion can move horizontally left and right in the second positioning hole.

2. A compact injection molding machine according to claim 1, wherein the connecting assembly further comprises a connecting block, the connecting block is fixed on the two sides of the head plate, an installation hole is arranged on the connecting block, the anti-rotation block is arranged in the installation hole, and the end of the spring connecting rod connected with the anti-rotation block is located in the installation hole; a first limiting part is arranged on the spring connecting rod, and a second limiting part is arranged on the connecting block, wherein the second limiting part is located on the side of the first limiting part away from the head plate, and the compression spring is located between the first limiting part and the second limiting part.

3. A compact injection molding machine according to claim 2, wherein a limiting groove is arranged on the spring connecting rod, and the side wall of the limiting groove close to the head plate constitutes the first limiting part; a connecting plate is arranged on the connecting block, the two ends of the connecting plate are respectively provided with an upward first limiting plate and a downward second limiting plate, and the top of the installation hole is provided with a downward third limiting plate, wherein The first limiting plate can abut against the third limiting plate, the second limiting plate constitutes the second limiting part, and the second limiting plate can be inserted into the limiting groove, one end of the compression spring is connected with the side wall of the limiting groove, and the other end of the compression spring is connected with the second limiting plate.

4. A compact injection molding machine according to claim 2 or 3, wherein The electric eye is arranged on the connecting block, and is used for monitoring the compression amount of the compression spring. The electric eye is electrically connected with the warning unit of the injection molding machine.

5. The indexing apparatus for a small injection molding machine of claim 1 wherein, The driving assembly comprises a driving motor and a transmission wheel set arranged on both sides of the integrated injection seat, the driving motor is fixed to the tail end of the integrated injection seat, the transmission wheel set comprises a motor pulley and two screw pulleys, the motor pulley is connected with the output shaft of the driving motor, the two screw pulleys are respectively connected with the two screws, and a synchronous belt is arranged between the motor pulley and the two screw pulleys.

6. A compact injection molding machine according to claim 5, wherein The transmission wheel set further comprises a tension pulley and two intermediate pulleys, the two intermediate pulleys are located between the two screw pulleys, and the tension pulley is located between the motor pulley and the screw pulley.

7. The indexing apparatus for a small injection molding machine of claim 1 wherein, The fixing member is a screw nut.

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