Method and system for controlling flow drill screws based on volatility

Abstract

The invention provides a method and a system for controlling a flow drill screw based on volatility. A method of installing a flow drill screw (FDS) into a substrate includes engaging the FDS with an automated tool and operating the tool at a first setting to drive the FDS into the substrate. The first setting rotates the FDS at a first rotational speed and applies a first axial feed force. The first arrangement causes the substrate to flow to allow the FDS to penetrate through the substrate. The method includes detecting, via a sensor, axial position data of the FDS while operating the automated tool, and calculating, via a controller, a volatility of the axial position data. The method includes switching the automatic tool from the first setting to a second setting in response to the volatility. The second setting rotates the FDS at a second rotational speed and applies a second axial feed force to the FDS. The second rotational speed is less than the first rotational speed.

Description

Technical Field

[0001] The present disclosure relates to a method and system for installing a flow drill screw. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] A flow drill screw (FDS) is a specific type of screw used to create a threaded joint between multiple substrates (one of which is a lower substrate) without the use of part preparation such as tapping or drilling a hole in the lower substrate. The lower substrate is typically metal, and the total number of substrates is typically two to four, but other numbers can be used. The upper substrate may or may not have a pre-formed through hole.

[0004] A typical FDS has a distal portion without threads or cutting edges and is configured to penetrate a substrate by locally heating the substrate using heat generated by rotational friction and axial pressure on the FDS. As the FDS penetrates the substrate, it forms threads in the substrate.

[0005] In a typical FDS process, an automated tool is controlled to rotate the FDS at a high revolutions per minute (RPM) while simultaneously applying an axial force toward the substrate. Typical FDS automated tools do not directly control axial position. This high RPM and force creates friction that heats the substrate and is maintained until the automated tool detects a trigger condition corresponding to the start of penetration from real-time measured data. Immediately after detecting this trigger condition, the automated tool's controller signals the automated tool to reduce the RPM and force. Thus, the automated tool reduces the RPM and force before the thread-forming portion of the FDS enters the substrate, allowing thread formation and tightening of the FDS against the substrate to occur at lower RPM and force. It is generally understood in the art that once penetration is achieved, the RPM and force should be reduced, but not before. It is generally accepted in the art that if the FDS has not fully penetrated before the RPM and force drop, it is likely that the FDS will ultimately not penetrate the underlying substrate at all. This is because the lower speed and force do not generate enough heat or force to continue penetrating and deforming the metal. Additionally, those skilled in the art generally recognize that it is important to reduce the RPM and force before the thread forming portion enters the bottom substrate so that there is adequate process control as the process nears completion (e.g., drive deceleration and final tightening) and the substrate is allowed to cool slightly before the thread forming portion enters the substrate and bushing area. It is also generally understood that it is critical that the RPM and force are low enough at the typical drop-off point in the process to have an acceptable ability to stop the process when the target torque value is reached without overshooting and stripping the joint.

[0006] It is important that the torque applied to the FDS during the penetration portion of the installation process does not rise above the rated torque value of the FDS.

[0007] The trigger condition is typically an axial position (ie, depth) or axial velocity (ie, depth gradient) threshold.

[0008] The teachings of the present disclosure address these and other problems of installing an FDS into a substrate. Summary of the Invention

[0009] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0010] In one form, the present disclosure provides a method for installing a flow drill screw (FDS) into a substrate, the method comprising engaging the FDS with an automatic tool. The method comprises operating the automatic tool in a first setting to drive the FDS into the substrate by causing the substrate to flow, thereby allowing the FDS to penetrate the substrate. The first setting is configured to rotate the FDS at a first rotational speed and apply a first axial feed force to the FDS. The first setting is configured to cause the substrate to flow, thereby allowing the FDS to penetrate the substrate. The method comprises detecting axial position data of the FDS via a sensor while operating the automatic tool. The method comprises calculating, via a controller, volatility of the axial position data of the FDS. The method comprises switching the automatic tool from the first setting to a second setting in response to the volatility. The second setting is configured to rotate the FDS at a second rotational speed and apply a second axial feed force to the FDS. The second rotational speed is less than the first rotational speed.

[0011] In a variation of the method of the above paragraphs that can be implemented individually or in any combination thereof: the controller switches the automatic tool from the first setting to the second setting in response to the controller determining that a trigger condition has occurred, the trigger condition including at least one of the value of the volatility exceeding a predetermined volatility value and the value of the volatility being within a predetermined range of a maximum volatility value; the predetermined volatility value is greater than or equal to 0.5 mm; the controller is configured to wait for a predetermined delay time after the controller determines that the trigger condition has occurred and before switching the automatic tool from the first setting to the second setting; the value is an average of the volatility within a time subset; the controller switches the automatic tool from the first setting to the second setting in response to reaching the maximum volatility value; the method also includes calculating a predicted maximum volatility value, wherein the controller switches the automatic tool from the first setting to the second setting based on the predicted maximum volatility value; the controller switches the automatic tool from the first setting to the second setting based on the predicted maximum volatility value but before reaching the maximum volatility value; the controller calculates the volatility using at least one of a true range (TR) formula and a standard deviation formula.

[0012] In another aspect, the present disclosure provides a method for installing a flow drill screw (FDS) into a substrate, the method comprising engaging the FDS with an automated tool. The method comprises operating the automated tool in a first setting to drive the FDS into the substrate by causing the substrate to flow, thereby allowing the FDS to penetrate the substrate. The first setting is configured to rotate the FDS at a first rotational speed and apply a first axial feed force to the FDS. The first setting is configured to cause the substrate to flow, thereby allowing the FDS to penetrate the substrate. The method comprises detecting axial position data of the FDS via a sensor while operating the automated tool. The method comprises calculating, via a controller, a volatility of the axial position data of the FDS. The method comprises switching, via the controller, the automated tool from the first setting to a second setting in response to the controller determining that a trigger condition has occurred. The trigger condition comprises at least one of: a value of the volatility exceeding a predetermined volatility value; and a value of the volatility being within a predetermined range of a maximum volatility value. The second setting is configured to rotate the FDS at a second rotational speed and apply a second axial feed force to the FDS. The second rotation speed is lower than the first rotation speed.

[0013] In a variation of the method of the above paragraphs that can be implemented individually or in any combination: the trigger condition includes the value of the volatility exceeding a predetermined volatility value, wherein the predetermined volatility value is greater than or equal to 0.5 mm; the trigger condition includes the value of the volatility being within a predetermined range of a maximum volatility value; the controller switches the automatic tool from the first setting to the second setting in response to reaching the maximum volatility value; the method also includes calculating a predicted maximum volatility value, wherein the controller switches the automatic tool from the first setting to the second setting based on the predicted maximum volatility value; the value is an average of the volatility within a time subset.

[0014] In yet another form, the present disclosure provides a system for installing a flow drill screw (FDS), the system comprising a drive unit, at least one sensor, and a controller. The drive unit is configured to rotate the FDS about an axis at a certain rotational speed while applying an axial feed force on the FDS to drive the FDS through at least one substrate. The at least one sensor is configured to detect axial position data of the FDS. The controller communicates with the at least one sensor. The controller is configured to determine the volatility of the axial position data of the FDS and change the rotational speed and the axial feed force in response to reaching a trigger condition. The trigger condition includes at least one of the following: the value of the volatility exceeds a predetermined volatility value; and the value of the volatility is within a predetermined range of a maximum volatility value.

[0015] In a variation of the system of the above paragraphs that can be implemented individually or in any combination: the trigger condition includes the value of the volatility exceeding the predetermined volatility value, wherein the predetermined volatility value is greater than or equal to 0.5 mm; the trigger condition includes the value of the volatility being within a predetermined range of a maximum volatility value; the value is an average of the volatility within a time subset; and the controller is configured to determine the volatility using at least one of a true range (TR) formula and a standard deviation formula.

[0016] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order that the present disclosure may be better understood, various forms of the present disclosure will now be described by way of example with reference to the accompanying drawings, in which:

[0018] Figure 1 is a side view of an example flow drill screw (FDS);

[0019] Figure 2During the installation process according to the teachings of the present disclosure Figure 1 A series of sequential stages of the FDS;

[0020] Figure 3 is a graph illustrating torque and screw position for an installation process for a flow drill screw in accordance with the teachings of the present disclosure;

[0021] Figure 4 is a graph illustrating axial velocity, screw position, and erroneous screw position measurements for a flow drill screw installation process according to the teachings of the present disclosure;

[0022] Figure 5 yes Figure 4 Detailed view of a portion of a graph illustrating how axial velocity control can correct erroneous screw position measurements;

[0023] Figure 6 is a graph showing a data graph of a flow drill screw installation process according to the teachings of the present disclosure, which shows a comparison of the fluctuation of screw speed and screw position data calculated using two different algorithms according to the teachings of the present disclosure;

[0024] Figure 7 yes Figure 6 a detailed view of a portion of the drawing; and

[0025] Figure 8 is a flow chart illustrating a method of installing a flow drill screw according to the teachings of the present disclosure.

[0026] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. DETAILED DESCRIPTION

[0027] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0028] refer to Figure 1, shows a typical FDS 10 having a head 14 and a shank 18 arranged about a rotational axis 22. The head 14 includes a clamping portion 26 and a tool engaging portion 30. The clamping portion 26 extends radially outward from the shank 18. The tool engaging portion 30 is configured to be gripped by an automated tool to rotate the FDS 10 about its rotational axis 22. The shank 18 extends axially from the clamping portion 26 to a tip 34. Between the tip 34 and the clamping portion 26 are a threaded portion 38, a thread-forming portion 42, a cylindrical portion 46, and an end portion 50. As shown, the tip 34 is typically rounded, relatively smooth, and relatively blunt, but some typical FDSs may have a more pointed tip. The end portion 50 includes the tip 34 and tapers radially outward toward the cylindrical portion 46. The end portion 50 and the cylindrical portion 46 are unthreaded. In some versions, the cylindrical portion 46 has a constant diameter. In other forms, the cylindrical portion 46 has a diameter that increases more gradually than the end portion 50. The threaded portion 38 has at least one full thread profile 54 disposed about the axis 22. The thread forming portion 42 is located axially between the cylindrical portion 46 and the threaded portion 38 and has at least one partial thread profile 58 that coincides with the at least one full thread profile 54 but tapers radially inwardly from the full thread profile 54 toward the cylindrical portion 46. In other words, the thread forming portion 42 has a partial-depth thread profile whose diameter (i.e., major thread diameter) narrows with increasing distance from the threaded portion 38. In some forms not shown, a typical FDS may have a second cylindrical portion between the clamping portion 26 and the threaded portion 38.

[0029] refer to Figure 1 and Figure 2 , shows sequential stages or states (labeled 1 to 6) of the FDS 10 during an installation process performed by an installation tool 110. The tool 110 is an automated tool that includes a driver 114, one or more sensors 118 (shown only in stage 1 for ease of illustration), and a controller 122 (shown only in stage 1 for ease of illustration). The driver 114 is configured to engage the tool engagement portion 30 of the FDS 10 to rotate the FDS 10 about its rotational axis 22 while applying an axial force toward a first substrate 210. The controller 122 is in communication with the driver 114 and the sensors 118 and is configured to control the operation of the driver 114 and receive input from the sensors 118.

[0030] The first substrate 210 can be any suitable material formed using any suitable process. In one form, the first substrate 210 is aluminum or an aluminum alloy. In another form, the first substrate 210 is magnesium or a magnesium alloy. In yet another form, the first substrate 210 is steel or a steel alloy. In yet another form, the first substrate 210 is a composite material. In some forms, the first substrate 210 can be a stamped sheet of material. In other forms, the first substrate 210 can be a casting. In other forms, the first substrate 210 can be an extrusion. In yet other forms, the first substrate can be forged.

[0031] Although not specifically shown, the driver 114 includes a motor (e.g., an electric motor, a hydraulic motor, or a pneumatic motor) configured to provide rotation and controlled by the controller 122. Although not specifically shown, the driver 114 also includes an actuator that can be actuated by any suitable power source (e.g., electric, hydraulic, or pneumatic power) to apply an axial force. The actuator is controlled by the controller 122. In one form, the actuator is a pneumatic actuator (e.g., a pneumatic cylinder) for applying an axial force. In one form, the driver 114 can optionally be provided on a robotic arm (not shown) or a base (not shown), and the controller 122 can be configured to control the movement of the robotic arm or base.

[0032] In a first stage, the FDS 10 is rotated while an axial force is applied on the FDS 10 in an axial direction towards the first substrate 210. In this first or initial stage, the first substrate 210 does not have any through holes at the locations where the FDS 10 is to be mounted.

[0033] In the example provided, the first substrate 210 is a lower substrate and the second substrate 214 is an upper substrate that is disposed on top of the first substrate 210 and is configured to be clamped to the first substrate 210 by the clamping portion 26 of the FDS 10. In the example provided, the second substrate 214 defines a pre-formed hole 218 having a diameter that is larger than the handle 18 but smaller than the clamping portion 26 so that the clamping portion 26 can clamp the second substrate 214 against the first substrate 210. Although only one second substrate 214 is shown, additional substrates may be used. For example, in some configurations not specifically shown, the FDS 10 may clamp one, two, three, four, or more additional substrates to the first substrate 210 in addition to the second substrate 214. These additional substrates may optionally have pre-formed through-holes, or the FDS may form holes therethrough. In Figure 2 In the example shown, the FDS 10 completely penetrates the first substrate 210 in the final stage 6 .

[0034] Although the first substrate 210 is Figure 2The first substrate 210 is shown as being thinner than the second substrate 214 , but in another form not specifically shown, the first substrate 210 may be thicker than the second substrate 214 .

[0035] In another alternative configuration not specifically shown, the first substrate 210 may be the top substrate and the second substrate may be the bottom substrate, but without the pre-formed holes 218 of the second substrate 214 ( Figure 2 ). In this alternative configuration, the FDS 10 can drill through the first substrate 210 and drill through the second substrate to clamp the first substrate 210 to the second substrate.

[0036] In yet another alternative configuration, not specifically shown, the second substrate may be omitted entirely, and the FDS 10 may be connected only to the first substrate 210. In some such forms, the FDS 10 may include connecting features (not shown, e.g., hooks, eyes, magnets, surfaces for receiving adhesive, etc.) such that mating features on another component may be coupled to the FDS 10 after the FDS 10 is attached to the first substrate 210.

[0037] Return to Figure 1 and Figure 2 In a first stage 1 (also referred to as a heating stage), the rotational speed and axial force of the tool 110 are configured to generate friction at the tip 34 to locally heat the substrate to a degree sufficient to melt or soften the substrate to a flowable state. Typically, the tool 110 continues to rotate the FDS 10 and apply axial pressure thereto until the FDS 10 is fully tightened in a final (e.g., sixth) stage 6 (also referred to as a tightening stage).

[0038] In Stage 2 (also known as the penetration stage), the end portion 50 of the FDS 10 begins to penetrate into the first substrate 210, but the cylindrical portion 46 has not yet entered the first substrate 210. In Stage 3, the cylindrical portion begins to enter the first substrate 210, but the thread-forming portion 42 has not yet entered the first substrate 210. Stage 3 is also known as the hole-forming stage because this is the stage where a small-diameter hole is formed in the first substrate 210. It should be understood that while Stage 3 is shown as the tip 34 completely penetrating the first substrate 210, depending on the thickness of the first substrate 210, the tip 34 may still be within the first substrate 210. In Stage 4, the thread-forming portion 42 begins to penetrate into the first substrate 210, but the threaded portion 38 has not yet entered the first substrate 210. Stage 4 is also known as the thread-forming stage because the thread-forming portion 42 forms threads at this stage. In Stage 5, the threaded portion 38 begins to penetrate the first substrate 210. During Stage 5 (also referred to as the drive deceleration stage), the threaded portion 38 is threaded into the threads formed by the thread forming portion 42, and the advancement of the FDS 10 is advanced axially into the first substrate 210 until the clamping portion 26 engages the second substrate 214 (or the clamping portion 26 engages the first substrate 210 in a form where the second substrate is located below the first substrate 210) to begin the final Stage 6. In Stage 6, also referred to as the tightening stage or final tightening stage, the FDS 10 is tightened until fully tightened.

[0039] In some embodiments, the sensor 118 may detect a predetermined end trigger condition, and the controller 122 may control the driver 114 to tighten the FDS 10 until the predetermined end trigger condition is reached. In one embodiment, the sensor 118 may include a torque sensor, and the end trigger condition may be a predetermined final torque value. The predetermined final torque value is less than the torsional strength rating of the FDS 10. In another embodiment, the sensor 118 may include a depth or position sensor to detect position data, and the predetermined end trigger condition may be the depth or position of the FDS 10 and / or a predetermined torque value.

[0040] refer to Figure 3 , shows torque and screw axial position (i.e., depth) as a function of time during the installation process of the FDS 10. In this graph, the maximum screw position (i.e., at line 410) refers to the position where the tip 34 of the FDS 10 initially contacts the first substrate 210, and a screw position of 0 mm (zero millimeters) refers to the final position where the clamping portion 26 clamps the second substrate 214 against the first substrate 210 (or where the clamping portion 26 engages the first substrate 210 in a form where the second substrate is below the first substrate 210).

[0041] refer to Figure 2 and Figure 3, Phase 1 (ie, the heating phase) begins at line 410 and proceeds to line 414. During this phase, torque rises, but the axial position of the FDS 10 remains stationary as heat builds.

[0042] Phase 2 (i.e., the penetration phase) begins at line 414. During this phase, as the tip 34 begins to penetrate the first substrate 210, the torque continues to rise to a first peak 418, and the axial position of the FDS 10 slowly advances downward (i.e., toward zero millimeters). As shown, as the first substrate 210 continues to soften due to the accumulation of heat, the axial position of the FDS 10 may begin to slowly move downward while the tip 34 continues to penetrate the first substrate 210.

[0043] Phase 3 (ie, the hole formation phase) begins at line 422. During this phase, as the cylindrical portion 46 enters the first substrate 210, the torque drops and the axial position of the FDS 10 moves rapidly downward.

[0044] Stage 4 (i.e., the thread forming stage) begins at line 426. During this stage, as the thread forming portion 42 enters and forms threads in the first substrate 210, the torque quickly rises to a second peak 430, and the axial position of the FDS 10 continues downward, albeit at a slower rate than during Stage 3.

[0045] Phase 5 (i.e., the drive deceleration phase) begins at line 434. During this phase, the torque decreases to a generally steady state as the axial position of the FDS 10 continues downward via the mating action of the threaded portion 38 and the threads formed in the first substrate 210 by the thread-forming portion 42 during Phase 4.

[0046] Phase 6 (ie, the final tightening phase) begins at line 438. During this phase, the torque is ramped up sharply while the axial position of the FDS 10 is maintained substantially at zero millimeters of torque ramp up until the end trigger condition is met and the controller 122 stops the rotation of the driver 114.

[0047] At the beginning of stage 1 (line 410), tool 110 is controlled to operate at a first setting, under which tool 110 is controlled to operate at a first rotational speed and a first axial feed force. At a point between the beginning of stage 3 (line 422) and the beginning of stage 6 (line 438), tool 110 is controlled to switch from the first setting to a second setting, wherein tool 110 is controlled to operate at a second RPM and a second axial feed force (which may optionally be the same or different from the first axial feed force). The first rotational speed is also referred to herein as a high rotational speed and may be in the range of 1,500 to 11,000 RPM (inclusive). In one form, the first rotational speed is more specifically in the range of 2,000 to 8,000 RPM (inclusive). In another form, the first rotational speed is more specifically in the range of 6,000 to 11,000 RPM (inclusive). The first axial feed force is also referred to as the high axial feed force in this article, and is in the range of 0.5 to 2.5 kilonewtons (kN) (inclusive). In one form, the first axial feed force can be in the range of 1 to 2kN. The second rotational speed is also referred to as the low rotational speed in this article, and is in the range of 500 to 4,000RPM (inclusive). In one form, the second rotational speed can be in this range but less than the first rotational speed, but other configurations can be used. The second axial feed force is also referred to as the low axial feed force in this article, and is in the range of 0.25 to 1.25kN (inclusive). In one form, the second axial feed force can be in this range but less than the first axial feed force, but other configurations can be used. For example, in another form, the second axial feed force can be equal to or greater than the first axial feed force.

[0048] refer to Figure 4 , shows two data sets of screw axial position (i.e., depth) of the same screw as a function of time during the installation process of the FDS 10. A first position curve 510 is formed from a first screw position data set measured by the sensor 118. A second position curve 514 is formed from a second screw position data set measured by the sensor 118. The difference 518 in the measured screw position data may be due to any number of factors (e.g., calibration errors between the two position sensors 118).

[0049] Figure 4 Also shown is the axial velocity 522 of the FDS 10 as a function of time during the installation process. Figure 4As shown, the axial velocity 522 is the same for both position profiles 510, 514. It has been found that even when the same sensor 118 is used to generate two position profiles for the same general process with subsequent screws, the axial velocity is substantially the same or differs only slightly (e.g., where the difference 518 in the measured position data is due to other factors such as dimensional tolerances in the FDS 10, tolerances in the first substrate 210, and / or tolerances in the second substrate 214).

[0050] refer to Figure 5 When a specific axial position (e.g., depth) value is used as a trigger point (e.g., threshold 610) to switch from a first setting (e.g., high rotational speed and high axial feed force) to a second setting (e.g., low rotational speed and low axial feed force), an error may result (illustrated by the distance 614 between the time when the first position data 510 intersects the value 610 and the time when the second position data 514 intersects the value 610). However, if the threshold 610 is a specific axial speed value rather than an axial position value, it has been found that this error is eliminated (as in the example shown) or greatly reduced while ensuring that the process can function as intended.

[0051] However, it has been found that due to a number of factors (e.g., signal propagation time, signal processing time, sampling speed, rotational momentum in the system), these typical trigger conditions (e.g., position thresholds or axial velocity thresholds) can ultimately be lagging indicators of the FDS 10's true position, particularly when smoothed axial velocity data is used. In other words, by the time the FDS 10's actual rotation and axial force decrease (compared to the time when the controller sends the signal to decrease rotation and axial force), the FDS 10 may have already exceeded the most desired axial position relative to the substrate. Furthermore, if raw axial velocity data is used, the data can be very noisy, i.e., producing an unsmooth data curve. This can also increase variability in the FDS's true position as to when the axial velocity thresholds are triggered by the raw axial velocity data.

[0052] However, axial velocity may still be a lagging indicator of actual FDS10 characteristics, as discussed in more detail in commonly owned U.S. patent application Ser. No. 18 / 466,775, filed Sep. 13, 2023, entitled “Method and System with Acceleration Based Flow Drill Screw Control,” the entire contents of which are incorporated herein by reference.

[0053] refer to Figure 6 and Figure 7 , controller 122( Figure 2 ) is configured to calculate in real time the Figure 2) detected axial position data (for example, Figures 3 to 5 The controller 122 may calculate the volatility of the axial position data by using a standard deviation algorithm (ST.DEV function or formula) on the axial position data, as indicated by graph 610. In another form, the controller 122 may calculate the volatility of the axial position data by using a true range algorithm (TR function or formula) on the axial position data, as indicated by graph 614. Although standard deviation and true range are shown, other volatility algorithms may be used.

[0054] The volatility algorithm may use any suitable look-back period. In one form, the volatility algorithm may use a look-back period of 10 ms, but other periods may be used.

[0055] Surprisingly, as in Figure 7 As best seen in FIG. 6 , the calculated volatility data sets (e.g., graphs 610 or 614) provide identifiable changes in the signal that have been found to be significant in FDS 10 ( Figure 1 and Figure 2 ) can be repeatably correlated with process conditions (e.g., during the installation phase) during the period of time that the process is being installed. The volatility algorithms can also provide smoother data curves when compared to the raw velocity data (graph 612), which can lead to more consistent results and the ability to more accurately detect changes in the data curve (e.g., from an initial steady state condition) earlier than other forms of data. As can be seen by at least the true range algorithm graph 614, some of these volatility algorithms can also provide identifiable changes in the signal earlier than other data sources (such as smoothed velocity data) (graph 616). Therefore, the controller 122 ( Figure 2 ) can be configured to check in real time when volatility data reaches a predetermined threshold volatility value.

[0056] In the example provided, the predetermined volatility threshold for the true range algorithm data (i.e., graph 614) may be greater than or equal to 0.5 mm (e.g., threshold 618), although other thresholds, including lower or higher values, may be used depending on where repeatable and identifiable variations exist for a particular FDS application signal. In the example provided, the predetermined volatility threshold for the standard deviation algorithm may be greater than or equal to 0.25 mm (e.g., threshold 622), although other thresholds, including lower or higher values, may be used depending on where repeatable and identifiable variations exist for a particular FDS application signal.

[0057] This threshold volatility value can provide a more accurate and repeatable trigger while also providing a leading indicator. In other words, the screw position volatility can provide a profile that can reproducibly produce an identifiable threshold trigger that occurs early enough in the installation process for the controller 122 to act on the threshold so that delays in data processing, signal propagation, and physical momentum of the components can be compensated. In other words, setting the trigger to the volatility threshold results in an earlier triggering of the controller 122 to send a control signal so that the FDS 10 actually physically reaches the second rotational speed and the second axial feed force faster than would normally be possible at the axial position or some other speed value threshold.

[0058] The value of the threshold value (also called trigger value) at line 618 or 622 is Figure 7 The values ​​shown in the figures are for illustrative purposes only and may be selected at volatility values ​​other than those shown. Actual volatility thresholds may also vary depending on the data collection process implemented, the type of volatility algorithm used, and, if applicable, the smoothing process implemented. For example, different data collection and / or volatility algorithms and / or smoothing processes may change the values ​​of the dataset being used, and the thresholds may be selected accordingly. Similarly, the values ​​of the data graphs or curves shown in the figures of the accompanying drawings are shown for illustrative purposes only and may vary depending on the data collection and / or smoothing process used.

[0059] In one form, the controller 122 may calculate the volatility directly from the raw axial position data. In another form, the controller 122 may apply a smoothing filter to the raw axial position data and then use the smoothed axial position data to calculate the volatility. In another form, the controller 122 may apply a smoothing filter to the calculated volatility data without first smoothing the raw axial position data before calculating the volatility. In another form, the controller 122 may apply a smoothing filter to the calculated volatility data and then calculate the volatility after smoothing the raw axial position data.

[0060] In one form, the controller 122 analyzes each volatility data value individually to determine whether it is at or above the volatility threshold. In another form, the controller 122 calculates an average of the volatility values ​​over a subset of time periods and analyzes the average to determine whether it is at or above the volatility threshold.

[0061] In one form, the volatility threshold 618 may be greater than or equal to 0.25 mm, although other thresholds may be used (e.g., 0.5 mm or 1 mm, or any value in the range of 0.25 mm to 4 mm), depending on the data collection and / or volatility algorithm and / or smoothing process used.

[0062] In one configuration of this form, the controller 122 immediately sends a control signal to switch to the second setting upon determining that the volatility data (e.g., 610 or 614) has reached or exceeded the volatility threshold 618. In another configuration of this form, the controller 122 immediately begins a predetermined time delay upon determining that the volatility data (e.g., 610 or 614) has reached or exceeded the volatility threshold 618 and then immediately sends a control signal to switch to the second setting at the end of the time delay. In some forms, this time delay may be between 1 and 30 ms, inclusive.

[0063] In yet another configuration of this form, the controller 122 does not use a predetermined time delay, but instead uses a predetermined axial position delay. In other words, the controller 122 immediately begins analyzing the measured axial position data upon determining that the volatility data (e.g., 610 or 614) has reached or exceeded the volatility threshold 618 and then immediately sends a control signal to switch to the second setting when the axial position data indicates that the FDS 10 has moved a predetermined axial distance after the volatility threshold 618. In some forms, the predetermined axial distance can be between 0.5 and 10 mm, inclusive. In some forms, the predetermined axial distance can be between 0.5 and 2 mm, inclusive. In some forms, the predetermined axial distance can be between 0.5 and 1 mm, inclusive.

[0064] In another form not specifically shown, the volatility threshold 618 may be set to the maximum volatility achieved (e.g., Figure 7 The controller 122 may be configured to switch to the second setting upon determining that the maximum volatility has been reached (e.g., point 626 or 630). In one configuration of this form, the controller 122 may switch immediately upon determining that the maximum volatility has been reached. In another configuration, the controller 122 may be configured to switch immediately after a predetermined time delay after the maximum volatility has been reached. In another configuration, the controller 122 may be configured to switch immediately after a predetermined axial position delay after the maximum volatility has been reached.

[0065] The controller 122 may determine the maximum volatility in any suitable manner, including, but not limited to, any of the following examples (alone or in any suitable combination thereof). In one example, the controller 122 compares each volatility value with subsequent volatility values ​​and determines that the maximum value is the value having at least two subsequent volatility values ​​lower than the maximum value. In another example, the controller 122 obtains derivatives of the volatility data values ​​in real time and determines that the maximum volatility is the value at which the derivative (i.e., slope) of the volatility curve (e.g., 610 or 614) begins to become negative.

[0066] In another example, the controller 122 may fit a mathematical model (e.g., a moving average) to the volatility data and predict when the volatility will reach a maximum value. In the example where the controller 122 predicts the maximum volatility, the controller 122 may switch to the second setting at a predetermined time or position before the maximum value so that delays in signal processing, momentum, etc. are compensated. In other words, the volatility threshold 618 may be within a predetermined range of the maximum volatility value.

[0067] refer to Figure 2 and Figure 8 , an installation process or method 910 is shown. The installation method 910 includes step 914. At step 914, one or more substrates (eg, the first substrate 210 and the second substrate 214) are positioned. The method 910 then proceeds to step 918.

[0068] At step 918 , the controller 122 positions the driver 114 to engage the FDS 10 and cause the tip 34 of the FDS 10 to contact the first substrate 210 at a predetermined location on the first substrate 210 . The method 910 then proceeds to step 922 .

[0069] The start of step 922 corresponds to line 410 ( Figure 4 At step 922, the controller 122 operates the automatic tool 110 in a first setting. For the first setting, the controller 122 controls the driver 114 to rotate at a first rotational speed and to apply a first axial force to the FDS 10. In other words, the controller 122 sends a signal to the driver 114 to cause the driver 114 to rotate the FDS 10 at the first rotational speed while pressing the FDS 10 against the first substrate 210 using the first axial feed force.

[0070] Although minor fluctuations may occur, the control signals from the controller 122 for the first setting are configured to operate the drive at a constant rotational speed and axial feed force during step 922 .

[0071] As shown by step 916 , while the driver 114 is applying the first rotational speed and the first axial feed force, the sensor 118 detects the depth or position of the FDS 10 The controller 122 receives a signal from the sensor 118 .

[0072] At step 920, the controller 122 calculates the volatility data (eg, the volatility data 610 or 614), as discussed above. As discussed above, the controller 122 may optionally apply a smoothing filter to the directly detected position data and / or the volatility data.

[0073] Returning to the example provided, at step 926, the controller 122 determines whether a predetermined first trigger condition is met based on the volatility data from step 920. The first trigger condition of method 910 is a threshold volatility value, such as threshold volatility value 618 ( Figure 7 ) and / or those thresholds discussed otherwise above.

[0074] The controller 122 continues to operate the driver 114 at the first rotational speed and the first axial feed force until the first trigger condition is satisfied. Detection of the first trigger condition is configured to cause the FDS 10 to activate the first trigger condition at line 422 ( Figure 3 ) and compensates for delays in data processing, signal propagation, and physical momentum of the components, as discussed above. When the first trigger condition is met, method 910 immediately and directly proceeds to step 930. In an alternative form, as discussed above, controller 122 may implement a time or position delay after the first trigger condition is met and then immediately proceed directly to step 930.

[0075] At step 930, the controller 122 operates the automatic tool 110 in the second setting. In the second setting, the controller 122 sends a signal to the driver 114 to immediately begin operating the driver 114 at the second rotational speed and the second axial feed force.

[0076] Although minor fluctuations may occur, the control signals from the controller 122 for the second setting are configured to operate the drive at a constant rotational speed and axial feed force during step 930 .

[0077] While the driver 114 is applying the second rotational speed and the second axial feed force, the sensor 118 can continue to detect the depth (ie, position) of the FDS 10 . The sensor 118 can also detect the torque value. The controller 122 continues to receive signals from the sensor 118 .

[0078] At step 934, the controller 122 determines whether a predetermined end trigger condition is met based on the signal from the sensor 118. The end trigger condition can be a final torque value. The controller 122 continues to operate the driver 114 at the second rotational speed and the second axial force until the end trigger condition is met. Once the end trigger condition is met, the controller 122 stops the rotation and axial force of the driver 114 to end the method, as indicated by step 938. It should be understood that additional steps can be taken when reaching step 938, and the end of the specific method discussed does not require that the driver 114 and / or the controller 122 must stop operating in all capacities at this time. For example, an industry standard process for torque control can be used to tighten the joint.

[0079] In another form, the devices and methods described herein may also be combined with the teachings of U.S. Application No. 18 / 365,660, filed on August 4, 2023, the entire disclosure of which is incorporated herein by reference. For example, the screw volatility threshold of the present disclosure may be used as the first trigger condition described in U.S. Application No. 18 / 365,660, rather than the axial velocity (i.e., depth gradient) described therein.

[0080] Thus, the methods and systems described herein compensate for variations in sensors, screw geometry, substrate geometry, and other manufacturing factors such as clearances from assembly and part fit in fixtures.

[0081] Unless otherwise expressly indicated herein, all numerical values ​​indicating mechanical / thermal properties, composition percentages, dimensions and / or tolerances or other characteristics when describing the scope of the present disclosure should be understood as modified by the word "about" or "approximately." Such modification is desirable for various reasons, including: industrial practice; material, manufacturing and assembly tolerances; and testing capabilities.

[0082] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical "or", and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0083] In this application, the terms "controller" and / or "module" may refer to, be part of, or include: an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinatorial logic circuit; a field-programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.

[0084] The term memory is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transient electrical or electromagnetic signals propagated through a medium (such as on a carrier wave); thus, the term computer-readable medium may be considered to be both tangible and non-transitory. Non-limiting examples of non-transitory tangible computer-readable media are non-volatile memory circuits (such as flash memory circuits, erasable programmable read-only memory circuits, or mask read-only circuits), volatile memory circuits (such as static random access memory circuits or dynamic random access memory circuits), magnetic storage media (such as analog or digital magnetic tape or hard drives), and optical storage media (such as CDs, DVDs, or Blu-ray discs).

[0085] The apparatus and methods described in this application may be implemented partially or completely by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. The functional blocks, flow chart components, and other elements described above serve as software specifications that can be translated into a computer program through routine work by a technician or programmer.

[0086] The description of the present disclosure is merely exemplary in nature and, thus, variations that do not depart from the essence of the disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.

[0087] According to the present invention, a method for installing a flow drill screw (FDS) into a substrate includes: engaging the FDS with an automatic tool; operating the automatic tool in a first setting to drive the FDS into the substrate by causing the substrate to flow to allow the FDS to penetrate the substrate, the first setting being configured to rotate the FDS at a first rotational speed and apply a first axial feed force on the FDS, the first setting being configured to cause the substrate to flow to allow the FDS to penetrate the substrate; detecting axial position data of the FDS via a sensor while operating the automatic tool; calculating, via a controller, a volatility of the axial position data of the FDS; and switching, via the controller, the automatic tool from the first setting to a second setting in response to the controller determining that a trigger condition has occurred, the trigger condition comprising at least one of: a value of the volatility exceeding a predetermined volatility value; and the value of the volatility being within a predetermined range of a maximum volatility value; wherein the second setting is configured to rotate the FDS at a second rotational speed and apply a second axial feed force to the FDS, wherein the second rotational speed is less than the first rotational speed.

[0088] In one aspect of the invention, the trigger condition comprises the value of the volatility exceeding the predetermined volatility value, wherein the predetermined volatility value is greater than or equal to 0.5 mm.

[0089] In one aspect of the invention, said trigger condition comprises said value of said volatility being within a predetermined range of maximum volatility values.

[0090] In one aspect of the invention, the controller switches the automatic tool from the first setting to the second setting in response to reaching the maximum volatility value.

[0091] In one aspect of the invention, the method includes calculating a predicted maximum volatility value, wherein the controller switches the automatic tool from the first setting to the second setting based on the predicted maximum volatility value.

[0092] In one aspect of the invention, said value is an average of said volatility over a subset of time.

Claims

1. A method of installing a flow drill screw (FDS) into a substrate, the method comprising: engaging the FDS with an automated tool; operating the automated tool in a first setting configured to rotate the FDS at a first rotational speed and exert a first axial feed force on the FDS to drive the FDS into the substrate by causing the substrate to flow to allow the FDS to penetrate the substrate, the first setting configured to cause the substrate to flow to allow the FDS to penetrate the substrate; detecting axial position data of the FDS via a sensor when operating the automatic tool; calculating, via a controller, fluctuations in the axial position data of the FDS; as well as The automatic tool is switched from the first setting to a second setting in response to the fluctuation, wherein the second setting is configured to rotate the FDS at a second rotational speed and apply a second axial feed force to the FDS, wherein the second rotational speed is less than the first rotational speed.

2. The method of claim 1 , wherein the controller switches the automatic tool from the first setting to the second setting in response to the controller determining that a trigger condition has occurred, the trigger condition comprising at least one of: The value of the volatility exceeds a predetermined volatility value; and The value of the volatility is within a predetermined range of maximum volatility values. The method according to claim 2 , wherein the predetermined waviness value is greater than or equal to 0.5 mm. 4 . The method of claim 2 , wherein the controller is configured to wait for a predetermined delay time after the controller determines that the trigger condition has occurred and before switching the automatic tool from the first setting to the second setting. The method of claim 2 , wherein the value is an average of the volatility over a subset of time.

6. The method of claim 1, wherein the controller switches the automatic tool from the first setting to the second setting in response to reaching a maximum volatility value.

7. The method of claim 1 , further comprising calculating a predicted maximum volatility value, wherein the controller switches the automatic tool from the first setting to the second setting based on the predicted maximum volatility value.

8. The method of claim 7, wherein the controller switches the automatic tool from the first setting to the second setting based on the predicted maximum volatility value but before the maximum volatility value is reached.

9. The method according to any one of claims 1 to 8, wherein the controller calculates the volatility using at least one of a True Range (TR) formula and a standard deviation formula.

10. A system for installing a flow drill screw (FDS), comprising: a driving unit configured to rotate the FDS about an axis at a certain rotational speed while applying an axial feed force on the FDS to drive the FDS through at least one substrate; at least one sensor configured to detect axial position data of the FDS; as well as a controller in communication with the at least one sensor, the controller configured to determine fluctuations in the axial position data of the FDS and to change the rotational speed and the axial feed force in response to a trigger condition being met, the trigger condition comprising at least one of: The value of the volatility exceeds a predetermined volatility value; and The value of the volatility is within a predetermined range of maximum volatility values.

11. The system of claim 10, wherein the trigger condition comprises the value of the volatility exceeding the predetermined volatility value, wherein the predetermined volatility value is greater than or equal to 0.5 mm.

12. The system of claim 10, wherein the trigger condition comprises the value of the volatility being within a predetermined range of maximum volatility values.

13. The system of claim 10, wherein the value is an average of the volatility over a subset of time.

14. The system of claim 10, wherein the controller is configured to wait for a predetermined delay time after the controller determines that the trigger condition has occurred and before changing the rotational speed and the axial feed force.

15. The system of any one of claims 10 to 14, wherein the controller is configured to determine the volatility using at least one of a True Range (TR) formula and a standard deviation formula.

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