Flow drill screw installation method to reduce installation torque and allow installation into thick materials

Abstract

The present disclosure provides a flow drill screw mounting method that reduces mounting torque and allows mounting into thick material. A method includes operating an automated tool at a first setting to drive a flow drill screw (FDS) into a substrate. The first setting is configured to rotate the FDS at a first rotational speed and apply a first axial feed force. The first arrangement is configured to cause the substrate to flow to allow the FDS to penetrate through the substrate. The method includes: detecting a predetermined first trigger condition including at least one of a depth gradient and a depth; and switching the tool from the first setting to a second setting in response to a predetermined second trigger condition including at least one of a predetermined axial feed distance after detecting the first trigger condition and a predetermined time delay after detecting the first trigger condition. The second setting is configured to rotate the FDS at a lower rotational speed and apply a lower axial feed force.

Description

Technical Field

[0001] The present disclosure relates to a method of 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 using part preparation such as tapping or drilling holes 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 preformed 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, the automatic tool is controlled to rotate the FDS at a high revolutions per minute (RPM) rate while applying a high axial force toward the substrate. A typical FDS automatic tool does not directly control the axial position. This high RPM, high force produces friction that heats the substrate and is maintained until the automatic tool detects a trigger condition corresponding to the start of penetration. Immediately upon detecting the trigger condition, the controller of the automatic tool signals the automatic tool to reduce RPM and force. Therefore, the automatic tool reduces RPM and force before the thread forming portion of the FDS enters the substrate, so that thread formation and the tightening of the FDS against the substrate can occur at lower RPM and force. It is generally understood in the art that once penetration is achieved, RPM and force should be reduced, rather than before. It is generally accepted in the art that if the FDS has not been fully penetrated before the RPM and force step drops, it is likely that the FDS will not penetrate the lower substrate at all in the end. This is because the lower speed and force do not generate enough heat to continue to penetrate. Additionally, it is generally recognized by those skilled in the art that it is important to reduce the RPM and force before the thread forming portion enters the substrate so that there is adequate process control near process completion (e.g., drive deceleration and final tightening) and the substrate is allowed to cool slightly before the thread forming portion enters the substrate. Finally, it is generally understood that the lowest temperature substrate will generally produce the highest stripping torque performance when the FDS is final tightened and torqued, which will reduce the chance of stripping the joint. It is also generally understood that it is critical that the RPM and force are low enough at the typical drop point of the process to have an acceptable ability to stop the process when the target torque value is reached, and not overshoot and strip 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. While typical FDS processes work well for some substrates, particularly for sheet metal less than 5 mm thick, it is generally understood that the torque required increases with increasing substrate thickness. Therefore, it may be difficult to install a typical FDS in relatively thick materials, such as substrates 5 mm or greater in thickness, without applying unacceptable levels of torque that could break the FDS during installation. In addition, reducing the installation torque requirements for substrates less than 5 mm may be advantageous for some applications. Known methods for reducing installation torque require additional materials, such as special lubricants. Other solutions that can be used for thicker materials require the use of specialized fasteners that are designed to withstand higher torques through material or geometry changes.

[0007] The teachings of the present disclosure address these and other problems of mounting a FDS in a substrate, and particularly in thicker substrates. Summary of the invention

[0008] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0009] In one form, the present disclosure provides a method of operating an automatic tool to install a flow drill screw (FDS) into a substrate. The method includes engaging the FDS with the automatic tool. The method includes operating the automatic tool at 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 is configured to rotate the FDS at a first rotational speed and apply a first axial feed force on the FDS. The first setting is configured to cause the substrate to flow to allow the FDS to penetrate the substrate. The method includes detecting a predetermined first trigger condition. The predetermined first trigger condition includes at least one of a depth gradient and a depth. The method includes switching the automatic tool from the first setting to a second setting in response to a predetermined second trigger condition. The predetermined second trigger condition includes at least one of a predetermined axial feed distance after detecting the predetermined first trigger condition and a predetermined time delay after detecting the predetermined first trigger condition. 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 lower than the first rotational speed, and the second axial feed force is lower than the first axial feed force.

[0010] In a variation of the method of the above paragraphs that may be implemented individually or in any combination: the predetermined first trigger condition includes a depth gradient; the depth gradient is between 40 mm / s and 200 mm / s, inclusive; the predetermined first trigger condition includes the depth; the shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defining a partial depth thread profile, the diameter of the partial depth thread profile narrowing as the distance from the threaded portion increases, wherein the tip portion tapers from the cylindrical portion to the end of the shank, wherein the The depth is the depth of the cylindrical portion entering the position where the substrate is located; the predetermined second trigger condition includes the predetermined axial feed distance after the predetermined first trigger condition is detected; the predetermined axial feed distance is 4 mm; the shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defines a partial depth thread profile, the diameter of the partial depth thread profile narrows as the distance from the threaded portion increases, wherein the tip portion tapers from the cylindrical portion to the end of the shank, wherein the predetermined axial feed distance corresponds to the the shank of the FDS comprises a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defining a partial depth thread profile, the partial depth thread profile being at a diameter, wherein the tip portion tapers from the cylindrical portion to an end of the shank, wherein the predetermined axial feed distance corresponds to an axial feed distance when the thread forming portion is at least partially within the substrate but the threaded portion is not yet located within the substrate; the predetermined second trigger condition comprises upon detecting the predetermined the predetermined time delay after the first trigger condition; the predetermined time delay is 20ms; the substrate has a thickness of 5mm or greater; the method also includes positioning one or more additional substrates adjacent to the substrate so that the FDS clamps the one or more additional substrates to the substrate after completing the method; the first rotational speed is between 3000RPM and 12000RPM (including end values), and the first axial feed force is between 0.5kN and 4kN (including end values), wherein the second rotational speed is between 500RPM and 4000RPM (including end values), and the second axial feed force is between 0.25kN and 1.25kN (including end values).

[0011] In another form, the present disclosure provides a method of operating an automatic tool to install a flow drill screw (FDS) into a substrate. The method includes engaging the FDS with the automatic tool. The method includes operating the automatic tool at 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 is configured to rotate the FDS at a first rotational speed and apply a first axial feed force on the FDS. The method includes detecting a predetermined first trigger condition. The predetermined first trigger condition includes a depth gradient. The method includes switching the automatic tool from the first setting to a second setting in response to a predetermined second trigger condition. The predetermined second trigger condition includes at least one of a predetermined axial feed distance after detecting the predetermined first trigger condition and a predetermined time delay after detecting the predetermined first trigger condition. 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, and the second axial feed force is less than the first axial feed force.

[0012] In a variation of the method of the above paragraphs that can be implemented individually or in any combination: the depth gradient is between 40mm / s and 200mm / s (including end values); the predetermined second trigger condition includes the predetermined axial feed distance after detecting the predetermined first trigger condition; the predetermined axial feed distance is 4mm; the first rotational speed is between 6000RPM and 10000RPM (including end values), and the first axial feed force is between 0.5kN and 3kN (including end values), wherein the second rotational speed is between 500RPM and 2500RPM (including end values), and the second axial feed force is between 0.25kN and 1.25kN (including end values).

[0013] In yet another form, the present disclosure provides a method of operating an automatic tool to install a flow drill screw (FDS) into a substrate. The shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion. The thread forming portion defines a partial depth thread profile, and the diameter of the partial depth thread profile narrows as the distance from the threaded portion increases. The tip portion is tapered from the cylindrical portion to the end of the shank. The method includes engaging the FDS with the automatic tool. The method includes operating the automatic tool under 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 is configured to rotate the FDS at a first rotational speed and apply a first axial feed force on the FDS. The method includes detecting a predetermined first trigger condition. The predetermined first trigger condition includes a depth gradient between 40 mm / s and 200 mm / s (including end values). The method includes switching the automatic tool from the first setting to a second setting in response to the thread forming portion of the FDS being at least partially within the substrate. 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, and the second axial feed force is less than the first axial feed force.

[0014] 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

[0015] 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:

[0016] FIG1 is a side view of an exemplary flow drill screw (FDS);

[0017] Figure 2 is a series of sequential stages of the FDS of FIG. 1 during an installation process according to the teachings of the present disclosure;

[0018] Figure 3 is a partial cross-sectional view of an FDS installed in an exemplary substrate according to the teachings of the present disclosure;

[0019] Figure 4 is a graph showing torque and screw position for an installation process for a flow drill screw in accordance with the teachings of the present disclosure;

[0020] Figure 5is a graph illustrating torque, screw position, and depth gradient for an installation process for a flow drill screw in accordance with the teachings of the present disclosure;

[0021] FIG6 is a flow chart of a typical installation process of a flow drill screw;

[0022] Figure 7 is a flow chart of a method of installing a flow drill screw according to the teachings of the present disclosure; and

[0023] Figure 8 The process of FIG6 shows the installation torque and Figure 7 A diagram comparing the installation torques for the various methods.

[0024] 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

[0025] 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 the same or corresponding parts and features.

[0026] Referring to FIG. 1 , a typical FDS 10 is shown, and the FDS has a head 14 and a shank 18 disposed about a rotation axis 22. The head 14 includes a clamping portion 26 and a tool engagement portion 30. The clamping portion 26 extends radially outward from the shank 18. The tool engagement portion 30 is configured to be clamped by an automatic tool to rotate the FDS about its rotation axis 22. The shank 18 extends in an axial direction 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 generally round, 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 not threaded. In some forms, 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 axially located 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 that has a diameter (i.e., a major thread diameter) that narrows as the distance from the threaded portion 38 increases. In some forms not shown, a typical FDS may have a second cylindrical portion between the clamping portion 26 and the threaded portion 38.

[0027] Refer to Figure 1 and Figure 2 , sequential stages or states (labeled 1 to 6) of the FDS 10 during an installation process performed by an installation tool 110 are shown. 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 sensor 118, and is configured to control the operation of the driver 114 and receive input from the sensor 118.

[0028] The first substrate 210 may 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 may be a stamped sheet of material. In other forms, the first substrate 210 may be a casting. In other forms, the first substrate 210 may be an extrusion. In yet other forms, the first substrate may be forged.

[0029] Although not specifically shown, the drive 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 drive 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 drive 114 can optionally be configured as a robotic arm (not shown), and the controller 122 can be configured to control the movement of the robotic arm.

[0030] In the first stage, the FDS 10 is rotated while exerting an axial force on the FDS 10 in the 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 location where the FDS 10 is to be mounted.

[0031] 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 FDS10. 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, in addition to the second substrate 214, the FDS10 may clamp one, two, three, four, or more additional substrates to the first substrate 210. 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 .

[0032] Although the first substrate 210 is Figure 2 is shown as being thinner than the second substrate 214, but as Figure 3 As shown, the first substrate (indicated by reference numeral 210 - 2 ) may be thicker than the second substrate 214 .

[0033] In another alternative configuration not specifically shown, the first substrate 210 may be a top substrate and the second substrate may be a bottom substrate, but without the pre-formed holes 218 of the second substrate 214 ( Figure 2 ). In this alternative configuration, the FDS 10 may drill through the first substrate 210 and drill through the second substrate to clamp the first substrate 210 to the second substrate.

[0034] 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 connection 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.

[0035] Return to Figure 1 and Figure 2 In the first stage 1 (also referred to as the 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 sufficient degree 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 the final (e.g., sixth) stage 6 (also referred to as the tightening stage).

[0036] In stage 2 (also referred to 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 referred to 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 although 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 referred to 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 screwed 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 the final tightening stage, the FDS 10 is tightened until fully tightened.

[0037] In some forms, the sensor 118 may detect a predetermined end trigger condition, and the controller 122 controls the driver 114 to tighten the FDS 10 until the predetermined end trigger condition. In one form, 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 form, the sensor 118 may include a depth or position sensor, and the predetermined end trigger condition may be the depth or position of the FDS 10.

[0038] refer to Figure 4 , shows torque and screw position (i.e., depth) over time during the installation process of the FDS 10. In the 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 the 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 in a form where the second substrate is below the first substrate 210, the clamping portion 26 engages the first substrate 210).

[0039] refer to Figure 3 and Figure 4, 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.

[0040] 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 accelerate downward while the tip 34 continues to penetrate the first substrate 210.

[0041] 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 rapidly accelerates downward.

[0042] 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.

[0043] Phase 5 (i.e., the drive deceleration phase) begins at line 434. During this phase, the torque decreases to a substantially 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.

[0044] Phase 6 (ie, the final tightening phase) begins at line 438. During this phase, the torque rises sharply while the axial position of the FDS 10 is maintained substantially at zero millimeters of torque rise until the end trigger condition is met and the controller 122 stops the rotation of the driver 114.

[0045] refer to Figure 5 , a graph showing torque, axial position (i.e., depth), and depth gradient (mm / s) of the FDS 10 during an installation process is shown. Line 510 indicates that the controller 122 sends a signal to the driver 114 to begin rotating the FDS 10 at a first RPM and applying a first axial force on the FDS 10 toward the first substrate 210. Line 514 indicates that the sensor 118 detects a first trigger condition. Line 518 indicates that a second trigger condition occurs. Line 522 indicates that an end trigger condition occurs. The dashed torque curve represents torque values ​​for a typical installation process, discussed in further detail below with reference to FIG. 6. The solid torque curve represents torque values ​​for an installation process of the present disclosure, and as discussed below with reference to Figure 7 Discussed in detail.

[0046] 6 , an exemplary installation process or method 610 is shown. The exemplary installation method 610 includes step 614. At step 614, one or more substrates (eg, first substrate 210 and second substrate 214) are positioned. The method 610 then proceeds to step 618.

[0047] At step 618 , 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 610 then proceeds to step 622 .

[0048] The start of step 622 corresponds to line 510 ( Figure 5 ). At step 622, the controller 122 operates the automatic tool 110 under the first setting. For the first setting, the controller 122 controls the driver 114 to rotate at a first rotational speed (i.e., RPM) and apply a first axial force on the FDS10. In other words, the controller 122 may send a signal to the driver 114 to cause the driver 114 to rotate the FDS10 at the first rotational speed while pressing the FDS10 against the first substrate 210 using the first axial feed force. The first rotational speed is also referred to as a high rotational speed herein, and is in the range of 3000RPM to 11000RPM (including end values). In one form, the first rotational speed is more specifically in the range of 6000RPM to 11000RPM (including end values). The first axial feed force is also referred to as a high axial feed force herein, and is in the range of 1 kilonewton (kN) to 2kN (including end values).

[0049] Although minor fluctuations may occur, the control signals from controller 122 for the first setting are configured to operate the drive at a constant rotational speed and axial feed rate during step 622 .

[0050] When the driver 114 applies 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.

[0051] At step 626, the controller 122 determines whether a predetermined first trigger condition is satisfied based on the signal from the sensor 118. The first trigger condition of the method 610 is the depth of the FDS 10 or the depth gradient of the FDS 10. For example, the sensor 118 can detect the position of the FDS 10 or the depth gradient. The controller 122 can be configured to determine the depth gradient based on the position measurement of the sensor 118. The controller 122 continues to operate the drive 114 at the first rotational speed and the first axial feed force until the first trigger condition is satisfied. The detection of the first trigger condition is indicated by line 514 ( Figure 5 ) and corresponds to line 422 ( Figure 4 ) at the start of phase 3. When the first trigger condition is met, method 610 immediately and directly proceeds to step 630.

[0052] At step 630, the controller 122 operates the automatic tool 110 at the second setting. At the second setting, the controller 122 sends a signal to the driver 114 to immediately start operating the driver 114 at a second rotational speed and a second axial feed force. The second rotational speed is also referred to herein as a low rotational speed and is in the range of 1500 RPM to 4000 RPM (including the end value), but is less than the first rotational speed. The second axial feed force is also referred to herein as a low axial feed force and is in the range of 0.25 kN to 1.25 kN (including the end value), but is less than the first axial feed force.

[0053] Although minor fluctuations may occur, the control signals from controller 122 for the second setting are configured to operate the drive at a constant rotational speed and axial feed rate during step 630 .

[0054] When the driver 114 applies the second rotational speed and the second 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.

[0055] At step 634, the controller 122 determines whether a predetermined end trigger condition is met based on the signal from the sensor 118. The end trigger condition may 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. The end trigger condition is represented by line 522 ( Figure 5 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 638.

[0056] In other words, the typical installation method 610 for the FDS 10 includes driving the FDS 10 at a preset high rotation speed and a preset high axial feed force, then immediately switching to a preset low rotation speed and a preset low axial feed force when the first trigger condition is detected, and maintaining the lower rotation speed and axial feed force until the FDS 10 is fully tightened. Therefore, the controller 122 controls the driver 114 to be at a lower rotation speed and a lower axial feed force before the thread forming portion 42 enters the first substrate 210.

[0057] refer to Figure 7 , shows an installation process or method 710 according to the present disclosure. Method 710 includes steps 714, 718, and 722. Steps 714, 718, and 722 may be the same as steps 614, 618, and 622, respectively. Then, method 710 proceeds from step 722 to step 726.

[0058] At step 726, the controller 122 determines whether a predetermined first trigger condition is satisfied based on the signal from the sensor 118. The first trigger condition of the method 710 may be the depth of the FDS 10 or the depth gradient of the FDS 10. For example, the sensor 118 may detect the position of the FDS 10 or the depth gradient. The controller 122 may be configured to determine the depth gradient based on the position measurement of the sensor 118. The controller 122 continues to operate the drive 114 at the first setting (i.e., at the first rotational speed and the first axial feed force) until the first trigger condition is satisfied. The detection of the first trigger condition is indicated by line 514 ( Figure 5 ) and corresponds to line 422 ( Figure 4 ) at the start of phase 3.

[0059] In some forms, the first trigger condition is a depth gradient in the range of 40 mm / s to 200 mm / s (inclusive). In one form, the first trigger condition is a depth gradient in the range of 80 mm / s to 120 mm / s (inclusive).

[0060] When the controller 122 identifies that the first trigger condition is met, the controller 122 continues to operate the drive 114 at the first setting (ie, at the first rotational speed and the first axial feed force), as indicated at step 730 .

[0061] At step 734, the controller 122 determines whether a predetermined second trigger condition is satisfied. The second trigger condition of method 710 may include a predetermined axial feed distance after the first trigger condition is detected and / or a predetermined time delay after the first trigger condition is detected. For example, in one form, the sensor 118 may detect a position or depth gradient of the FDS 10, and the controller 122 may be configured to determine whether the FDS 10 has been axially advanced a predetermined axial feed distance. In another form, the controller 122 may determine whether a predetermined time delay has passed since the first trigger condition was detected. The controller 122 continues to operate the drive 114 at the first setting (i.e., at the first rotational speed and the first axial feed force) until the second trigger condition is satisfied. Detection of the second trigger condition is indicated by line 518 ( Figure 5 When the second trigger condition is met, the method 710 proceeds to step 738.

[0062] At step 738, the controller 122 sends a signal to the driver 114 to immediately begin operating the driver 114 at the second setting (i.e., at a second rotational speed and a second axial feed force). The second rotational speed is also referred to herein as a low rotational speed and is in the range of 1500 RPM to 4000 RPM (inclusive), but is less than the first rotational speed. The second axial feed force is also referred to herein as a low axial feed force and is in the range of 0.25 kN to 1.25 kN (inclusive), but is less than the first axial feed force.

[0063] Although minor fluctuations may occur, the control signal from controller 122 for the second setting may be configured to operate the drive at a constant rotational speed and axial feed rate during step 738 .

[0064] In one form, the second trigger condition is a predetermined time delay and / or a predetermined position corresponding to line 426 ( Figure 4 ). Due to inertia in the components of the driver 114 and the time delay for the signal from the controller 122 to reach the driver 114, the FDS 10 will continue at the first rotational speed and the first axial feed force as the thread forming portion 42 enters and begins to act on the first substrate 210. Therefore, when the thread forming portion 42 has acted on the first substrate 210, the FDS 10 reaches the second rotational speed and the second axial feed force.

[0065] In another form, the second trigger condition is a predetermined time delay and / or a predetermined position corresponding to within stage 4 (i.e., between lines 426 and 434 ( Figure 4)). Therefore, the controller 122 continues to operate the driver 114 to drive the FDS 10 at the first rotational speed and the first axial feed force while the thread forming portion 42 acts on the first substrate 210, and sends a signal to reduce the first rotational speed and the first axial feed force only after the thread forming portion 42 has begun to act on the first substrate 210. In this form, the signal to reduce the speed from the controller 122 is sent before the threaded portion 38 enters the first substrate 210. The signal can be sent so that the FDS 10 reaches the second rotational speed and the second axial feed force before or after the threaded portion 38 enters the first substrate 210.

[0066] In yet another form, the second trigger condition is a predetermined time delay and / or a predetermined position corresponding to at or after the end of stage 4 (i.e., at line 434 ( Figure 4 Therefore, the controller 122 continues to operate the driver 114 to drive the FDS 10 at the first rotational speed and the first axial feed force while the thread forming portion 42 acts on the first substrate 210, and sends a signal to reduce the rotational speed and the axial feed force when or after the threaded portion 38 has entered the first substrate 210.

[0067] In some forms, the predetermined position of the second trigger condition may be 4 millimeters (mm) axially moved toward the first substrate 210 after the first predetermined trigger condition is satisfied. The axial position or time delay of the second trigger condition depends on the axial length of the cylindrical portion 46.

[0068] In some forms, the second trigger condition is a predetermined time delay of 20 milliseconds (ms).

[0069] At step 742, the controller 122 determines whether a predetermined end trigger condition is met based on the signal from the sensor 118. The end trigger condition may 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. The end trigger condition is represented by line 522 ( Figure 5 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 746.

[0070] In other words, the installation method 710 for the FDS 10 includes maintaining the FDS 10 at a preset high rotational speed and a preset high axial feed force until after the thread forming portion 42 has begun to act on the first substrate 210, and then switching to a preset low rotational speed and a preset low axial feed force to achieve drive deceleration and subsequent final tightening. Therefore, the controller 122 detects when the cylindrical portion 46 enters the first substrate 210, and does not reduce the speed and axial feed force until after the thread forming portion 42 enters the first substrate 210. Therefore, the temperature of the first substrate 210 does not decrease until after the thread forming portion 42 has begun to form threads in the first substrate 210.

[0071] Reference now Figure 8 , shows a graph showing the unexpected results of method 710 compared to method 610. The X-axis is the thickness of the first substrate 210 (in mm). The Y-axis is the torque required to install the FDS 10. It can be seen that for all thicknesses (including Figure 8 The thickness of the first substrate 210 is not specifically shown in the figure), and it has been found that the installation torque of method 610 is significantly greater than the installation torque of method 710. Therefore, the thickness of the first substrate 210 can be any thickness. In some forms, the thickness of the first substrate 210 is greater than or equal to 5 mm. In other forms, the thickness can be less than 5 mm.

[0072] 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 to be modified by the word "about" or "approximately". Such modifications are desirable for a variety of reasons, including: industrial practice; material, manufacturing and assembly tolerances; and testing capabilities.

[0073] 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."

[0074] 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 (e.g., an operational amplifier circuit integrator as part of a heat flux data module); or a combination of some or all of the above, such as in a system on a chip.

[0075] 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); therefore, the term computer-readable medium may be considered to be 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 tape or hard drives), and optical storage media (such as CDs, DVDs, or Blu-ray discs).

[0076] The apparatus and methods described in this application may be implemented partially or completely by a special-purpose computer, which is 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 are used as software specifications, which can be translated into a computer program by routine work of a technician or programmer.

[0077] The description of the present disclosure is merely exemplary in nature, and thus, variations that do not depart from the essence of the present disclosure are intended to be within the scope of the present disclosure. Such variations should not be regarded as a departure from the spirit and scope of the present disclosure.

[0078] According to the present invention, a method of operating an automatic tool to install a flow drill screw (FDS) into a substrate includes: engaging the FDS with the 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 a predetermined first trigger condition, the predetermined first trigger condition comprising at least one of a depth gradient and a depth; and switching the automatic tool from the first setting to a second setting in response to a predetermined second trigger condition, the predetermined second trigger condition comprising at least one of a predetermined axial feed distance after detecting the predetermined first trigger condition and a predetermined time delay after detecting the predetermined first trigger condition, 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 and the second axial feed force is less than the first axial feed force.

[0079] In one aspect of the invention, the depth gradient is between 40 mm / s and 200 mm / s, inclusive.

[0080] In one aspect of the present invention, the predetermined second trigger condition comprises the predetermined axial feed distance after the predetermined first trigger condition is detected.

[0081] In one aspect of the present invention, the predetermined axial feed distance is 4 mm.

[0082] In one aspect of the present invention, the first rotational speed is between 6000RPM and 10000RPM (including end values), and the first axial feed force is between 0.5kN and 3kN (including end values), wherein the second rotational speed is between 500RPM and 2500RPM (including end values), and the second axial feed force is between 0.25kN and 1.25kN (including end values).

[0083] According to the present invention, a method of operating an automatic tool to install a flow drill screw (FDS) into a substrate, wherein the shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defining a partial depth thread profile, the diameter of the partial depth thread profile narrowing as the distance from the threaded portion increases, wherein the tip portion tapers from the cylindrical portion to an end of the shank, the method comprising: engaging the FDS with the automatic tool; operating the automatic tool in a first setting to install the FDS into the substrate by causing the substrate to flow to allow the FDS to penetrate the substrate The FDS is driven into 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; detecting a predetermined first trigger condition, the predetermined first trigger condition comprising a depth gradient between 40 mm / s and 200 mm / s (inclusive); and switching the automatic tool from the first setting to a second setting in response to the thread forming portion of the FDS being at least partially within the substrate, 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 and the second axial feed force is less than the first axial feed force.

Claims

1. A method of operating an automated tool to install a flow drill screw (FDS) into a substrate, the method comprising: engaging the FDS with the automatic tool; operating the automatic 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 a predetermined first trigger condition, the predetermined first trigger condition comprising at least one of a depth gradient and a depth; as well as switching the automatic tool from the first setting to a second setting in response to a predetermined second trigger condition, the predetermined second trigger condition comprising at least one of a predetermined axial feed distance after detection of the predetermined first trigger condition and a predetermined time delay after detection of the predetermined first trigger condition, 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 and the second axial feed force is less than the first axial feed force. The method of claim 1 , wherein the predetermined first trigger condition comprises the depth gradient.

3. The method of claim 2, wherein the depth gradient is between 40 mm / s and 200 mm / s, inclusive. The method of claim 1 , wherein the predetermined first trigger condition comprises the depth.

5. The method of claim 4, wherein the shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defining a partial depth thread profile having a diameter that narrows as the distance from the threaded portion increases, wherein the tip portion tapers from the cylindrical portion to an end of the shank, The depth is the depth of the cylindrical portion entering the location of the substrate. 6 . The method of claim 1 , wherein the predetermined second trigger condition comprises the predetermined axial feed distance after the predetermined first trigger condition is detected. The method according to claim 6 , wherein the predetermined axial feed distance is 4 mm.

8. The method of claim 6, wherein the shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defining a partial depth thread profile having a diameter that narrows with increasing distance from the threaded portion, wherein the tip portion tapers from the cylindrical portion to an end of the shank, The predetermined axial feed distance corresponds to an axial feed distance at which the thread forming portion is at least partially located within the substrate.

9. The method of claim 6, wherein the shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defining a partial depth thread profile having a diameter that narrows with increasing distance from the threaded portion, wherein the tip portion tapers from the cylindrical portion to an end of the shank, The predetermined axial advance distance corresponds to an axial advance distance at which the thread forming portion is at least partially within the substrate but the threaded portion is not yet located within the substrate.

10. The method of claim 1, wherein the predetermined second trigger condition comprises the predetermined time delay after detecting the predetermined first trigger condition. The method according to claim 10 , wherein the predetermined time delay is 20 ms.

12. The method according to claim 1, wherein the substrate has a thickness of 5 mm or more.

13. The method of claim 1, further comprising positioning one or more additional substrates adjacent to the substrate such that the FDS clamps the one or more additional substrates to the substrate after completion of the method.

14. The method of claim 1, wherein the shank of the FDS includes a threaded portion, a thread forming portion adjacent to the threaded portion, a cylindrical portion adjacent to the thread forming portion, and a tip portion adjacent to the cylindrical portion, the thread forming portion defining a partial depth thread profile having a diameter that narrows with increasing distance from the threaded portion, wherein the tip portion tapers from the cylindrical portion to an end of the shank, wherein the predetermined first trigger condition includes the depth gradient, wherein the predetermined second trigger condition comprises the predetermined axial feed distance after the predetermined first trigger condition is detected, and The predetermined axial feed distance corresponds to an axial feed distance at which the thread forming portion is at least partially located within the substrate.

15. The method according to any one of claims 1 to 14, wherein the first rotational speed is between 3000RPM and 12000RPM, inclusive; and the first axial feed force is between 0.5kN and 4kN, inclusive; wherein the second rotational speed is between 500RPM and 4000RPM, inclusive; and the second axial feed force is between 0.25kN and 1.25kN, inclusive.

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