A screw cap control method and a servo screw cap machine

Abstract

The application discloses a screw cap control method and a servo screw cap machine, and belongs to the technical field of screw caps. The screw cap control method comprises the following steps: S1, starting a servo motor and controlling the output rotating speed of the servo motor to increase to a first rotating speed, so as to drive a screw cap assembly to rotate a bottle cap at the first rotating speed; S2, detecting the output torque of the servo motor and the rotating number of the bottle cap, when the output torque reaches a first torque threshold value or the rotating number reaches a preset number of turns, the output rotating speed is switched from the first rotating speed to a second rotating speed, and the output torque is controlled to increase; and S3, when the output torque reaches a second torque threshold value, the servo motor is controlled to keep the output torque as the second torque threshold value. The servo screw cap machine is applied to the screw cap control method.

Description

Technical Field

[0001] This invention relates to the field of capping technology, and more particularly to a capping control method and a servo capping machine. Background Technology

[0002] In the liquid packaging industry, capping machines are commonly used to secure caps to bottles, sealing them. A capping machine is a sealing device that fastens caps to bottles filled with product. The capping torque of the machine directly affects the sealing performance of the bottle and the torque required for the consumer to open it. Specifically, the higher the capping torque, the better the seal, but the greater the torque required to open the cap, making it more difficult for consumers to open and less acceptable. Conversely, the lower the capping torque, the worse the seal; too low a torque can even lead to leakage, rendering the seal ineffective. In this case, even a small opening torque is meaningless. Therefore, a balance must be struck between sealing performance and opening force—achieving both high sealing performance and minimal opening torque.

[0003] In existing technology, capping is performed using a servo capping machine. The servo capping machine includes a servo motor and a capping assembly. The capping assembly grips the cap and then places it on the bottle. The servo motor drives the capping assembly to rotate, screwing the cap onto the bottle. The servo motor drives the capping assembly to rotate according to a set torque until the feedback torque received by the servo motor exceeds the maximum torque. Both the set torque and the maximum torque can be calculated experimentally or theoretically, ensuring that the capping assembly, driven by the servo motor, smoothly installs the cap onto the bottle with high sealing performance, preventing leakage, and avoiding excessive torque required for opening, all within acceptable limits for the user.

[0004] However, in actual operation, since the servo motor is usually connected to the capping assembly through a transmission chain or other connection structure, when the servo motor stops outputting torque after receiving the maximum feedback torque, the capping machine will have rotational inertia. Under the action of rotational inertia, the capping assembly cannot stop capping immediately, but will continue to cap, causing the capping torque to continue to increase. This will result in the capping torque exceeding the allowable range of capping torque, affecting the capping effect. Summary of the Invention

[0005] The purpose of this invention is to provide a capping control method and a servo capping machine to solve the technical problem in the prior art where the capping control method is affected by the inertia moment of the transmission chain, resulting in sluggish feedback from the transmission chain and excessive capping torque, which leads to difficulty in opening the cap.

[0006] Based on the above concept, the technical solution adopted by this invention is as follows:

[0007] On one hand, the present invention provides a capping control method, comprising:

[0008] S1. Start the servo motor and control the output speed of the servo motor to increase to a first speed, thereby driving the capping assembly to rotate the bottle cap at the first speed;

[0009] S2. Detect the output torque of the servo motor and the number of rotations of the bottle cap. When the output torque reaches a first torque threshold or the number of rotations reaches a preset number of rotations, control the output speed to switch from the first speed to the second speed, and at the same time control the output torque to increase.

[0010] S3. When the output torque reaches the second torque threshold, control the servo motor to maintain the output torque at the second torque threshold.

[0011] Preferably, the number of rotations is the sum of the number of idle rotations and the number of reserved rotations.

[0012] Preferably, in step S1, before the capping assembly grips the cap, the servo motor is started to idle and the output speed of the servo motor is controlled to increase to a first speed.

[0013] Preferably, in S2, when the output speed is switched from the first speed to the second speed, the output torque of the servo motor first decreases and then gradually recovers.

[0014] Preferably, when the output torque reaches the second torque threshold, the output speed gradually decreases until it reaches zero.

[0015] Preferably, the second rotational speed is less than or equal to 120 revolutions per minute.

[0016] Preferably, in step S2, if the first rotational speed is less than or equal to 240 rpm, within a set time value during which the output rotational speed switches from the first rotational speed to the second rotational speed, it is determined whether the output torque is lower than a set threshold. If so, it indicates that the bottle cap torque is normal; otherwise, the bottle cap torque is in an abnormal state.

[0017] Preferably, in step S2, if the first rotational speed is greater than 240 rpm, after the output rotational speed is switched from the first rotational speed to the second rotational speed, it is determined whether the time value for which the servo motor drives the bottle cap to rotate at the second rotational speed is greater than or equal to a preset time value. If so, it indicates that the bottle cap torque is normal; otherwise, the bottle cap torque is in an abnormal state.

[0018] Preferably, the first rotational speed satisfies a preset relationship, which is:

[0019]

[0020] Where v1 represents the first rotation speed, X represents the preset number of capping rotations, T represents the preset capping duration, T1 represents the duration of the servo motor running at the first rotation speed, and T2 represents the preset time value.

[0021] On the other hand, the present invention also provides a servo capping machine, including a servo motor, a capping assembly, and a controller connected to both the servo motor and the capping assembly. The servo motor is driven and connected to the capping assembly, and the controller controls the operation of the servo motor and the capping assembly according to the capping control method described above.

[0022] The beneficial effects of this invention are:

[0023] The capping control method proposed in this invention improves capping efficiency by first increasing the output speed of the servo motor to a higher first speed, enabling the rapid completion of most of the capping rotations. Secondly, when the output torque reaches a first torque threshold or the number of rotations reaches a preset number, the speed is switched to a lower second speed while simultaneously increasing the output torque. This staged control effectively reduces the impact of the transmission chain's moment of inertia on the capping process. It prevents the capping assembly from continuing to cap after reaching the preset torque due to moment of inertia, thus preventing the capping torque from continuously increasing beyond the allowable opening torque range. This ensures that the capping torque remains within a suitable range, guaranteeing both sealing performance and an acceptable opening torque for the user. When the output torque reaches a second torque threshold, the servo motor is controlled to maintain the output torque at this threshold, stabilizing the final capping effect and further ensuring the quality and reliability of the capping process. Attached Figure Description

[0024] Figure 1 This is a graph showing the relationship between output torque and time provided in Embodiment 1 of the present invention;

[0025] Figure 2 This is a graph showing the relationship between output rotational speed and time provided in Embodiment 1 of the present invention;

[0026] Figure 3 This is a schematic diagram of the servo capping machine provided in Embodiment 2 of the present invention;

[0027] Figure 4 This is a schematic diagram of the operation process of the servo capping machine provided in Embodiment 2 of the present invention.

[0028] In the picture:

[0029] 1. Servo motor; 2. Capping head; 3. Cap gripping head; 4. Capping support; 5. Lifting cam; 6. Gear set; 7. Capping arm; Q1. Translation section; Q2. Cap gripping descent section; Q3. Cap gripping translation section; Q4. Capping descent section; Q5. Capping section; Q6. Lifting section. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] See Figure 1 and Figure 2 The capping control method provided in this embodiment of the invention includes: S1, starting the servo motor and controlling the output speed of the servo motor to increase to a first speed, thereby driving the capping assembly to rotate the bottle cap at the first speed; S2, detecting the output torque of the servo motor and the number of rotations of the bottle cap, and when the output torque reaches a first torque threshold or the number of rotations reaches a preset number of rotations, controlling the output speed to switch from the first speed to a second speed, and simultaneously controlling the output torque to increase; S3, when the output torque reaches the second torque threshold, controlling the servo motor to maintain the output torque at the second torque threshold.

[0036] The capping control method proposed in this invention improves capping efficiency by first increasing the output speed of the servo motor to a higher first speed, enabling the rapid completion of most of the capping rotations. Secondly, when the output torque reaches a first torque threshold or the number of rotations reaches a preset number, the speed is switched to a lower second speed while simultaneously increasing the output torque. This staged control effectively reduces the impact of the transmission chain's moment of inertia on the capping process. It prevents the capping assembly from continuing to cap after reaching the preset torque due to moment of inertia, thus preventing the capping torque from continuously increasing beyond the allowable opening torque range. This ensures that the capping torque remains within a suitable range, guaranteeing both sealing performance and an acceptable opening torque for the user. When the output torque reaches a second torque threshold, the servo motor is controlled to maintain the output torque at this threshold, stabilizing the final capping effect and further ensuring the quality and reliability of the capping process.

[0037] The specific steps of the capping control method are described below.

[0038] S1. Start the servo motor and control the output speed of the servo motor to increase to the first speed, thereby driving the capping assembly to rotate the bottle cap at the first speed;

[0039] In S1, before the capping assembly grips the cap, the servo motor is started to idle and its output speed is increased to a first speed, shortening the overall capping process time and thus further improving capping efficiency. Furthermore, increasing the speed to the first speed in advance allows for a faster response to subsequent cap gripping and capping actions, reducing time delays caused by the start-up and acceleration processes, making the entire capping process smoother and more efficient.

[0040] S2. Detect the output torque of the servo motor and the number of rotations of the bottle cap. When the output torque reaches the first torque threshold or the number of rotations reaches the preset number of rotations, control the output speed to switch from the first speed to the second speed, and at the same time control the output torque to increase.

[0041] The output speed can be switched based on torque. When the torque reaches a first torque threshold, the output speed is switched from the first speed to a second speed. This switching method is controlled by the set torque; each capping operation reaches the set first torque threshold before switching speeds. Therefore, the remaining tightening turns for each capping operation are very similar, resulting in similar low-speed capping times. At the same production speed, by adjusting the first torque threshold, the switching time can be controlled, thereby controlling the remaining tightening amount and achieving high production capacity by controlling the low-speed tightening time.

[0042] However, it is worth noting that this switching method is only suitable for bottles and caps with significant torque changes during the capping process, such as bottles and caps with anti-theft rings; it is not suitable for bottles and caps with increased torque that tighten quickly.

[0043] In addition, the output speed can be switched based on the rotation. When the number of rotations reaches a preset number, the output speed is switched from the first speed to the second speed. This switching method has no requirements on the fit between the bottle and the cap, and is suitable for all types of bottles and caps.

[0044] This switching method, due to the uncertainty of the thread alignment position, means that the starting point of the cap may not necessarily start screwing into the thread. It needs to idle until it reaches the starting point of the thread (the amount of idle rotation depends on the number of thread heads, and a single thread head needs a maximum of 1 idle rotation). This results in varying amounts of remaining tightening. It is necessary to ensure that the time required for the maximum number of rotations remaining is used for low-speed tightening. The number of rotations is the sum of the number of idle rotations and the reserved number of rotations, which takes a long time and results in lower production capacity.

[0045] This invention employs a first rotation speed to quickly complete the required number of cap rotations, then switches to a second rotation speed for low-speed tightening, thus achieving... Figure 1 and Figure 2 The curve variation relationship in the figure is used to reduce the influence of the moment of inertia of the capping drive chain on the capping torque.

[0046] The first rotational speed satisfies a preset relationship, which is:

[0047]

[0048] Where v1 represents the first rotation speed, X represents the preset number of capping rotations, T represents the preset capping duration, T1 represents the duration of the servo motor running at the first rotation speed, and T2 represents the preset time value.

[0049] The second rotation speed is less than or equal to 120 rpm. Specifically, when the second rotation speed is less than or equal to 80 rpm, the capping effect is optimal (the opening torque fluctuation range is the smallest); when the second rotation speed is greater than 80 rpm but less than or equal to 120 rpm, the capping torque fluctuation range is acceptable; however, when the second rotation speed is greater than 120 rpm, the opening torque fluctuation is large and may exceed the limit range.

[0050] See Figure 1 and Figure 2 In the T3-T4 section, when the output speed switches from the first speed to the second speed, the output torque of the servo motor first decreases and then gradually recovers. During the switch, the torque initially decreases due to the reduced speed, preventing damage to the capping assembly, cap, or bottle due to sudden torque changes. Once the speed stabilizes, the torque recovers and gradually increases, ensuring the tightening force during the capping process.

[0051] To ensure capping quality, torque anomaly detection is necessary. Specifically, in step S2, if the first rotational speed is less than or equal to 240 rpm, within the set time interval between the first and second rotational speeds, it is determined whether the output torque is below a set threshold. If so, the cap torque is normal; otherwise, the cap torque is abnormal. Figure 2 As shown, the set time value is t3-t4.

[0052] If the first rotational speed is greater than 240 rpm, after the output speed switches from the first to the second rotational speed, it is determined whether the time for the servo motor to drive the bottle cap to rotate at the second rotational speed is greater than or equal to a preset time value. If so, it indicates that the bottle cap torque is normal; otherwise, the bottle cap torque is in an abnormal state. Figure 2 As shown, the preset time value is t4-t5.

[0053] S3. Once the output torque reaches the second torque threshold, control the servo motor to maintain the output torque at the second torque threshold. Ensure that after capping is complete, the torque remains at the second torque threshold for the specified time; otherwise, the torque will be too low. Afterward, the capping cycle is complete, and the next cycle begins. Figure 1 As shown, the rated time is t5-t6.

[0054] like Figure 2 As shown, when the output torque reaches the second torque threshold, the output speed gradually decreases until it reaches zero. The t4-t5 segment of the speed change curve guarantees the maximum torque. If the output speed drops directly to zero at point t4, the tightening torque will be affected by the moment of inertia, causing the opening torque to exceed the acceptable range.

[0055] Regarding the setting of the first and second torque thresholds, one approach is to uniformly set them, where the first torque threshold equals the maximum torque of the high-speed capping, and the second torque threshold equals the maximum torque of the capping head. Setting the same first and second torque thresholds for any capping head results in different switching torques due to the friction of the capping drive chain. This can easily lead to problems such as excessively high capping or excessive torque. To reduce or eliminate the impact of no-load friction, the friction of the drive chain needs to be reduced, leading to increased production costs.

[0056] Alternatively, a first torque threshold and a second torque threshold can be set independently for each capping head. This method can compensate for the no-load friction of each capping drive chain, thereby reducing the requirements for the production accuracy of the drive chain and reducing production costs. However, as the equipment runs longer, the friction decreases, requiring frequent adjustments.

[0057] In addition, a compensation setting can be used, where the first torque threshold is equal to the difference between the maximum torque of the high-speed capping and the frictional torque of the capping arm under no-load conditions; and the second torque threshold is equal to the difference between the maximum torque of the capping and the frictional torque of the capping arm under no-load conditions, thereby avoiding the influence of the frictional torque of the capping drive chain on the torque threshold.

[0058] In actual operation, the required torque setting method can be selected adaptively according to actual needs, and no limitation is made here.

[0059] Example 2

[0060] This invention also provides a servo capping machine, which includes a servo motor 1, a capping assembly, and a controller (not shown). The controller is connected to both the servo motor 1 and the capping assembly, specifically through a control connection. The servo motor 1 is connected to the capping assembly and is used to drive the capping assembly to rotate, thereby causing the capping assembly to cap.

[0061] Specifically, such as Figure 3 As shown, the capping assembly includes a capping head 2 and a cap gripping head 3. The cap gripping head 3 is connected to the capping head 2 and is used to grip the cap. When the capping head 2 rotates, it drives the cap gripping head 3 to rotate, thereby causing the cap gripping head 3 to grip the cap and rotate it to attach the cap to the bottle.

[0062] Optionally, the servo capping machine also includes a capping support 4, a lifting cam 5, a gear set 6, and a capping arm 7. The lifting cam 5 controls the height position of the capping arm 7 at different circumferential angles; the servo motor 1 outputs capping torque, controlling the speed and torque of the capping arm 7. The gear set 6, capping arm 7, capping head 2, and cap gripping head 3 together form a capping transmission chain, used to transmit the torque and speed of the servo motor 1 to the cap gripping head 3.

[0063] Specifically, the output of the servo motor 1 is driven by the gear set 6, which is driven by the capping arm 7. The capping head 2 is connected to the capping arm 7. The capping support 4 supports the capping arm 77 and rotates it around the cam structure to grip caps on the capping conveyor line or to cap them on different bottle conveyor lines. The gripping head 3 grips the caps and transmits the capping torque and speed to them.

[0064] The working principle of the servo capping machine provided in this embodiment is as follows:

[0065] The capping transmission chain consists of servo motor 1, gear set 6, capping arm 7, capping head 2, and cap gripping head 3. Servo motor 1 directly drives the cap gripping head 3 to rotate, performing the capping. The capping support 4 is powered by a support base and rotates synchronously with the bottles on the filling production line, ensuring each cap gripping head 3 corresponds to one bottle. The lifting cam 5 has grooves of varying heights on its circumference, within which the bearing of the capping arm 7 moves; the lifting cam 5 is fixed in place by the support base. As the capping arm 7 rotates with the capping support 4, the lifting cam 5 controls the height of the capping arm 7, allowing for different operations in different areas.

[0066] like Figure 4 As shown, the capping arm 7 rotates one revolution and passes through the translation section Q1, the cap-grabbing descent section Q2, the cap-grabbing translation section Q3, the cap-screwing descent section Q4, the cap-screwing section Q5, and the rising section Q6 in sequence. When the capping arm 7 is in the cap-grabbing descent section, it grabs the cap through the cap-grabbing head 3. When the capping arm 7 is in the cap-screwing section, it performs the capping operation.

[0067] It should be noted that the rotation direction of the capping support 4 can be adjusted according to the production line. For more specific working steps of the servo capping machine, please refer to the prior art; this embodiment does not limit it.

[0068] The above embodiments merely illustrate the basic principles and characteristics of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A capping control method for controlling a servo capping machine, the servo capping machine comprising a servo motor, a capping assembly, and a controller connected to both the servo motor and the capping assembly, wherein the servo motor is connected to the capping assembly and is used to drive the capping assembly to move, characterized in that... The capping control method includes: S1. Start the servo motor and control the output speed of the servo motor to increase to a first speed, thereby driving the capping assembly to rotate the bottle cap at the first speed; S2. Detect the output torque of the servo motor and the number of rotations of the bottle cap. When the output torque reaches a first torque threshold or the number of rotations reaches a preset number of rotations, control the output speed to decrease from the first speed to the second speed, and simultaneously control the output torque to increase. When the output speed decreases from the first speed to the second speed, the output torque of the servo motor first decreases and then gradually recovers. S3. When the output torque reaches the second torque threshold, the output speed gradually decreases until it reaches zero, and the servo motor is controlled to maintain the output torque at the second torque threshold.

2. The capping control method according to claim 1, characterized in that, The number of rotations is the sum of the number of idle rotations and the number of reserved rotations.

3. The capping control method according to claim 1, characterized in that, In S1, before the capping assembly grips the cap, the servo motor is started to idle and the output speed of the servo motor is controlled to increase to a first speed.

4. The capping control method according to claim 1, characterized in that, The second rotational speed is less than or equal to 120 revolutions per minute.

5. The capping control method according to claim 1, characterized in that, In step S2, if the first rotational speed is less than or equal to 240 rpm, within a set time value during which the output rotational speed switches from the first rotational speed to the second rotational speed, it is determined whether the output torque is lower than a set threshold. If so, it indicates that the bottle cap torque is normal; otherwise, the bottle cap torque is in an abnormal state.

6. The capping control method according to claim 1, characterized in that, In step S2, if the first rotational speed is greater than 240 rpm, after the output rotational speed is switched from the first rotational speed to the second rotational speed, it is determined whether the time value for which the servo motor drives the bottle cap to rotate at the second rotational speed is greater than or equal to a preset time value. If so, it indicates that the bottle cap torque is normal; otherwise, the bottle cap torque is in an abnormal state.

7. A servo capping machine, characterized in that, The device includes a servo motor (1), a capping assembly, and a controller connected to both the servo motor (1) and the capping assembly. The servo motor (1) is driven and connected to the capping assembly. The controller controls the operation of the servo motor (1) and the capping assembly according to any one of claims 1 to 6.

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