A high-precision linear motion mechanism applied to a precision photoelectric instrument

Abstract

The application provides a high-precision linear motion mechanism applied to a precise photoelectric instrument.The mechanism comprises a driving assembly, a feedback assembly, a planetary gear reducer transmission assembly, a synchronous belt transmission assembly, a ball screw transmission assembly, a guide assembly, a shell, an end cover and a slide plate structure.The mechanism is specifically a motion mechanism capable of adjusting the position of a target along the direction of an optical axis in a collimator, has high linear motion precision, shaking precision and resolution, and has good temperature stability of each precision, and when the mechanism is used in cooperation with an upper computer, high-precision adjustment of the position of the target can be conveniently and quickly performed, and the mechanism has the characteristics of low cost, easy assembly, large stroke, strong load capacity, compact structure and rich application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of precision machinery and optoelectronic instruments, and in particular relates to a high-precision linear motion mechanism for use in precision optoelectronic instruments. Background Technology

[0002] Linear motion mechanisms have a wide range of applications in the field of optoelectronic instruments, and the target adjustment mechanism in a collimator is one such typical application. A collimator is a commonly used precision optoelectronic instrument in optical laboratories. By illuminating a target with a light source, it can simulate a target at infinity, making it an essential piece of equipment for the assembly, adjustment, and testing of optical systems.

[0003] The target is a substrate with etched lines or patterns. The etched lines or patterns vary depending on the test. Common targets include crosshairs, star-shaped aperture plates, resolution plates, and Boltzmann plates. Therefore, collimators require frequent target replacements during use. After each target replacement, a motion mechanism is needed to adjust the target to the focal plane of the collimator's optical system in order to image the target at infinity. Currently, research on target adjustment mechanisms is limited. Existing target adjustment mechanisms are typically manual, with overly simple structures that cannot accurately adjust the target to the focal plane of the optical system and are cumbersome to operate. Therefore, the purpose of this invention is to propose a linear motion mechanism that enables automatic adjustment of the collimator target, featuring high motion accuracy and a high degree of automation. Summary of the Invention

[0004] The purpose of this invention is to address the problems in existing technologies by proposing a high-precision linear motion mechanism for use in precision optoelectronic instruments. Specifically, this mechanism is a motion mechanism used in collimators to adjust the target position along the optical axis. It possesses high linear motion accuracy, wobbling accuracy, and resolution, with good temperature stability across all accuracy parameters. When used with a host computer, it allows for convenient and quick high-precision adjustment of the target position. Furthermore, it features low cost, easy assembly, large stroke, strong load capacity, compact structure, and wide applicability.

[0005] The present invention is achieved through the following technical solution: The present invention proposes a high-precision linear motion mechanism for precision optoelectronic instruments, the mechanism including a drive component, a feedback component, a planetary gear reducer transmission component, a synchronous belt transmission component, a ball screw transmission component, a guide component, a housing, an end cover, and a slide plate structure.

[0006] The drive component is a brake stepper motor, and its tail brake can achieve self-locking when power is off.

[0007] The feedback component includes a position feedback sensor and limit switches; the position feedback sensor feeds back the slide position information to the control system in real time, thereby realizing closed-loop control of the stepper motor; the limit switches are distributed at the positive and negative limit positions of the slide, which can realize the electrical limit protection of the mechanism.

[0008] The planetary gear reducer transmission assembly includes a planetary gear reducer and a reducer bracket; the planetary gear reducer is directly connected to the stepper motor and then fixed to the housing by the reducer bracket; the mounting interface of the planetary gear reducer on the reducer bracket is a slotted hole.

[0009] The synchronous belt drive assembly includes a driving synchronous pulley, a driven synchronous pulley, and a synchronous belt; the driving and driven synchronous pulleys are respectively fixedly mounted on the output shaft of the planetary gear reducer and the input shaft of the ball screw using their own set screws;

[0010] The ball screw transmission assembly includes a ball screw and its nut, a fixed-side support unit, and a supporting-side support unit. The fixed-side support unit and the supporting-side support unit are matching components for the ball screw, each containing two angular contact ball bearings and one deep groove ball bearing, which are fixed to corresponding holes on the housing and end cover with screws. The two ends of the ball screw are installed in the support unit, and the ball screw nut is fixed to the slide plate with screws, thereby converting the rotary motion of the stepper motor into the linear motion of the slide plate.

[0011] The guide assembly consists of three identical linear bearing assemblies, which are parallel to each other and evenly distributed on the circumference. Each linear bearing assembly consists of two linear bearings and a light shaft. The two linear bearings are respectively installed in corresponding holes in the end cap and the housing, and are axially limited by a shaft retaining spring. The light shaft passes through the corresponding two linear bearings and is fixed to the slide plate by a shrink-fitting connecting sleeve.

[0012] Furthermore, the mechanism is driven by a brake stepper motor with an integrated brake at the tail. The rotational motion of the brake stepper motor is transmitted to the ball screw via a planetary gear reducer and a synchronous belt. The ball screw then converts the rotational motion into linear motion and transmits it to the slide plate. The slide plate is guided by three sets of parallel linear bearing assemblies during its movement.

[0013] Furthermore, the slide plate is a moving part in the mechanism, and it has multiple sets of threaded holes as mechanical interfaces for mounting the carrier.

[0014] Furthermore, the housing and end cap are fixed together by screws and positioned using two internally threaded tapered pins, together forming the outer shell of the mechanism; the housing and end cap have mounting holes for the fixed-side support unit and the supporting-side support unit of the linear bearing and ball screw, as well as mounting threaded holes for the reducer bracket, the reading head adapter seat and the limit switch, and mechanical interfaces are reserved for connection with other components.

[0015] Furthermore, the slide plate has threaded holes for mounting the target assembly; the position of the slide plate is fed back in real time by a grating ruler in conjunction with a reading head, and the brake stepper motor is controlled in a closed loop; the grating ruler is a steel strip grating ruler, which is attached to the grating ruler base with its own adhesive backing, and the grating ruler base is fixed to the slide plate with screws; the reading head is fixed to the housing through a reading head adapter.

[0016] Furthermore, there is a limit switch at each of the positive and negative extreme positions of the slide plate, which, together with the limit baffle installed on the slide plate, can realize the electrical limit protection of the mechanism.

[0017] Furthermore, the brake stepper motor is fixed to the planetary gear reducer by screws, and its output shaft is tightened to the input shaft of the planetary gear reducer by the fastening screws provided with the planetary gear reducer; the planetary gear reducer is fixed to the reducer bracket by screws, and then the reducer bracket is fixed to the housing by screws; the mounting interface of the planetary gear reducer on the reducer bracket is a slotted hole, so as to adjust the shaft spacing between the output shaft of the planetary gear reducer and the ball screw, thereby realizing the installation and tensioning of the synchronous belt; the reducer bracket and the housing are positioned by a "one-face, two-pin" method.

[0018] Furthermore, the two ends of the ball screw are installed in the matching fixed-side support unit and the supporting-side support unit, and the ball screw nut is fixed to the slide plate by screws. The fixed-side support unit and the supporting-side support unit are fixed to the end faces of the housing and the end cover by screws respectively.

[0019] Furthermore, the selected expansion coupling sleeve is a self-nut type, which can firmly fix the optical axis and the slide plate by simply tightening the nut during use.

[0020] Furthermore, the housing and end cap are connected by screws, and the corresponding linear bearing mounting holes and ball screw support unit mounting holes are machined in combination, specifically:

[0021] (1) Before assembly, the housing and end cap are positioned using two conical pins to ensure that their relative positions remain unchanged when disassembled and reassembled.

[0022] (2) After positioning with a tapered pin, use a boring machine to machine the corresponding mounting holes at the same time.

[0023] The advantages of this invention compared to the prior art are as follows:

[0024] 1. The present invention provides a high-precision linear motion mechanism for precision optoelectronic instruments with a structure of "two linear bearings and one optical axis". This structure improves the wobbling accuracy of the mechanism and effectively eliminates the adverse effects of different thermal expansion coefficients of parts in the traditional structure of "one linear bearing and one optical axis", thereby improving the temperature stability of the mechanism's motion accuracy.

[0025] 2. The high-precision linear motion mechanism for precision optoelectronic instruments provided by the present invention uses a stepper motor for driving and a position feedback element for closed-loop control, which gives the mechanism the advantages of high linear motion accuracy and resolution.

[0026] 3. The high-precision linear motion mechanism for precision optoelectronic instruments provided by this invention has a high degree of automation. The stepper motor, which is the driving component, can be controlled by a microcontroller. It also has functions such as real-time position display and electrical limit protection, making it very convenient to operate and use.

[0027] 4. The high-precision linear motion mechanism for precision optoelectronic instruments provided by the present invention has the feature of easy assembly. In order to simplify the assembly process, the following measures are taken: (1) The housing and end cap are processed in combination to ensure the coaxiality of the corresponding holes; (2) The mechanism uses commercial shelf products such as ball screw support unit and expansion coupling sleeve; (3) Multiple positioning measures are designed, such as positioning pins and positioning stops. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of a high-precision linear motion mechanism applied to precision optoelectronic instruments according to the present invention;

[0030] Figure 2 This is a schematic diagram showing the connection between the brake stepper motor and the planetary gear reducer.

[0031] Figure 3 A cross-sectional view of the ball screw drive assembly and guide assembly;

[0032] Figure 4 A schematic diagram of the planetary gear reducer mounting interface on the reducer bracket;

[0033] Figure 5 This is a schematic diagram of the installation of the position feedback sensor and the limit baffle.

[0034] The following numbers are labeled in the diagram: 1 is the end cap, 2 is the housing, 3 is the brake stepper motor, 4 is the planetary gear reducer, 5 is the reducer support, 6 is the driving synchronous pulley, 7 is the synchronous belt, 8 is the driven synchronous pulley, 9 is the slide plate, 10 is the shaft retaining circlip, 11 is the linear bearing, 12 is the optical shaft, 13 is the limit switch, 14 is the reading head adapter, 15 is the reading head, 16 is the expansion coupling sleeve, 17 is the ball screw, 18 is the fixed side support unit, 19 is the ball screw nut, 20 is the support side support unit, 21 is the internal threaded tapered pin, 22 is the grating ruler seat, 23 is the grating ruler, 24 is the limit baffle, and 25 is the fastening screw. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Combination Figures 1-5 This invention proposes a high-precision linear motion mechanism for precision optoelectronic instruments. The mechanism includes a drive assembly, a feedback assembly, a planetary gear reducer transmission assembly, a synchronous belt transmission assembly, a ball screw transmission assembly, a guide assembly, a housing, an end cap, and a slide plate structure.

[0037] The drive component is a brake stepper motor, and its tail brake can achieve self-locking when power is off.

[0038] The feedback component includes a position feedback sensor and limit switches; the position feedback sensor feeds back the slide position information to the control system in real time, thereby realizing closed-loop control of the stepper motor; the limit switches are distributed at the positive and negative limit positions of the slide, which can realize the electrical limit protection of the mechanism.

[0039] The planetary gear reducer transmission assembly includes a planetary gear reducer and a reducer bracket, which can effectively improve the output capacity of the stepper motor while ensuring a compact structure. The planetary gear reducer is directly connected to the stepper motor and then fixed to the housing by the reducer bracket. The mounting interface of the planetary gear reducer on the reducer bracket is a slotted hole to facilitate adjustment of the shaft spacing between the output shaft of the planetary gear reducer and the ball screw, thereby realizing the installation and tensioning of the synchronous belt.

[0040] The synchronous belt drive assembly includes driving and driven synchronous pulleys and a synchronous belt. Compared to using a coupling to connect the reducer and the ball screw, using a synchronous belt drive effectively reduces the size of the mechanism, making its structure more compact and reasonable. The driving and driven synchronous pulleys are respectively fixedly mounted on the output shaft of the planetary gear reducer and the input shaft of the ball screw using their own set screws.

[0041] The ball screw transmission assembly includes a ball screw and its nut, a fixed-side support unit, and a supporting-side support unit. The fixed-side support unit and the supporting-side support unit are ball screw matching assemblies, each containing two angular contact ball bearings and one deep groove ball bearing, which are fixed to corresponding holes on the housing and end cover with screws. Using the support unit simplifies the assembly process and reduces production costs. The ball screw and its nut are selected as pre-loaded products. Pre-loaded ball screw assemblies can avoid backlash. Both ends of the ball screw are installed in the support unit, and the ball screw nut is fixed to the slide plate with screws, thereby converting the rotary motion of the stepper motor into the linear motion of the slide plate.

[0042] The guide assembly consists of three identical linear bearing assemblies, which are parallel to each other and evenly distributed on the circumference. Each linear bearing assembly consists of two linear bearings and a light shaft. The two linear bearings are respectively installed in corresponding holes in the end cap and the housing, and are axially limited by a shaft retaining spring. The light shaft passes through the corresponding two linear bearings and is fixed to the slide plate by a shrink-fitting connecting sleeve.

[0043] The wobbling accuracy of the skateboard during movement depends on the fit clearance and effective contact length between the linear bearing and the optical shaft. Compared with the traditional structure of "one linear bearing with one optical shaft", the structure of "two linear bearings with one optical shaft" increases the load capacity of the mechanism and significantly increases the effective contact length, thereby greatly improving the wobbling accuracy of the skateboard during movement.

[0044] The aforementioned structure of "one linear bearing paired with one optical shaft" requires the two ends of the optical shaft to be fixed to the housing and end cap respectively. Commercially available optical shafts are typically made of steel, while the housing and end caps are usually made of aluminum. In this structure, due to the different coefficients of thermal expansion of the two materials, changes in ambient temperature will cause the optical shaft to exert a load on the housing and end caps, leading to a decrease in the motion accuracy of the mechanism itself. The aforementioned structure of "two linear bearings paired with one optical shaft" avoids this phenomenon.

[0045] The housing and end cap are connected by screws. The corresponding linear bearing mounting holes and ball screw support unit mounting holes are machined in combination to ensure high coaxiality between the corresponding holes. Specifically:

[0046] (1) Before assembly, the housing and end cap are positioned using two conical pins to ensure that their relative positions remain unchanged when disassembled and reassembled.

[0047] (2) After positioning with a tapered pin, use a boring machine to machine the corresponding mounting holes at the same time.

[0048] The slide plate is a moving part in the mechanism, and it has multiple sets of threaded holes as mechanical interfaces for mounting the carrier.

[0049] The implementation of the technical solution will be further described in detail below with reference to the accompanying drawings, in order to more clearly illustrate the structure and its operation method.

[0050] like Figure 1 As shown, a high-precision linear motion mechanism for precision optoelectronic instruments is driven by a brake stepper motor 3 with an integrated brake at the tail. The rotational motion of the brake stepper motor 3 is transmitted to the ball screw 17 via a planetary gear reducer 4 and a synchronous belt 7. The ball screw 17 then converts the rotational motion into linear motion and transmits it to the slide plate 9. The slide plate 9 is guided by three sets of parallel linear bearings 11 during its movement.

[0051] The housing 2 and end cap 1 are fastened together with screws and positioned using two internally threaded tapered pins 21, together forming the outer shell of the mechanism. Mounting holes are provided on the housing 2 and end cap 1 for the linear bearing 11, the fixed-side support unit 18 of the ball screw 17, and the supporting-side support unit 20, as well as threaded mounting holes for the reducer bracket 5, the reading head adapter 14, and the limit switch 13. Mechanical interfaces are also provided for connection to other components. Specifically, the dimensions and tolerances of the corresponding linear bearing mounting holes and ball screw support unit mounting holes must be consistent, and a high degree of coaxiality between the corresponding holes is also required. Therefore, a combined machining method is used to process them simultaneously.

[0052] The sliding plate 9 is the moving part of the mechanism, and it has threaded holes for mounting the target assembly. The position of the sliding plate 9 is fed back in real time by the grating ruler 23 in conjunction with the reading head 15, and the brake stepper motor 3 is controlled in a closed loop, thereby achieving high linear motion accuracy of the mechanism. The grating ruler 23 is a steel strip grating ruler, which is attached to the grating ruler base 22 with its own adhesive backing. The grating ruler base 22 is fixed to the sliding plate 9 with screws. The reading head 15 is fixed to the housing 2 through the reading head adapter 14.

[0053] There is a limit switch 13 at each of the positive and negative extreme positions of the slide plate 9. Together with the limit baffle 24 installed on the slide plate 9, they can achieve electrical limit protection for the mechanism. Figure 5 As shown.

[0054] The brake stepper motor 3 is fixed to the planetary gear reducer 4 by screws, and its output shaft is tightened to the input shaft of the planetary gear reducer 4 by the fastening screws 25 provided with the planetary gear reducer 4. Figure 2 As shown. The planetary gear reducer 4 is fixed to the reducer bracket 5 by screws, and the reducer bracket 5 is then fixed to the housing 2 by screws. Figure 4 As shown, the mounting interface of the planetary gear reducer 4 on the reducer bracket 5 is a slotted hole, which facilitates the adjustment of the shaft spacing between the output shaft of the planetary gear reducer 4 and the ball screw 17, thereby enabling the installation and tensioning of the synchronous belt 7. Meanwhile, to ensure that the rotational planes of the driving synchronous pulley 6 and the driven synchronous pulley 8 are basically coincident, and to avoid abnormal wear of the synchronous belt 7 leading to a reduced lifespan, the reducer bracket 5 and the housing 2 are positioned using a "one-face, two-pin" method.

[0055] The synchronous belt drive assembly includes a synchronous belt 7, a driving synchronous pulley 6, and a driven synchronous pulley 8. The driving synchronous pulley 6 and the driven synchronous pulley 8 are respectively fixedly mounted on the output shaft of the planetary gear reducer 4 and the input shaft of the ball screw 17 using their own set screws.

[0056] like Figure 3 As shown, the two ends of the ball screw 17 are installed in the matching fixed side support unit 18 and the support side support unit 20. The ball screw nut 19 is fixed to the slide plate 9 by screws. The fixed side support unit 18 and the support side support unit 20 are fixed to the end faces of the housing 2 and the end cover 1 by screws respectively.

[0057] Three sets of parallel linear bearing assemblies, roughly evenly distributed around the circumference, are responsible for guidance. Each set of linear bearing assemblies consists of two linear bearings 11 and an optical axis 12. Figure 1 As shown. Two linear bearings 11 in the assembly are respectively mounted on the end cap 1 and the housing 2. Each linear bearing has a circlip 10 at both ends for axial positioning. The optical shaft 12 simultaneously passes through the corresponding two linear bearings 11 and is fixed to the slide plate 9 by a tightening coupling sleeve 16, as shown. Figure 2 As shown. The selected expansion coupling sleeve is a self-nut type, which can firmly fix the optical axis 12 and the slide plate 9 by simply tightening the nut.

[0058] The above provides a detailed description of a high-precision linear motion mechanism for precision optoelectronic instruments proposed in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A high-precision linear motion mechanism for use in precision optoelectronic instruments, characterized in that, The mechanism includes a drive assembly, a feedback assembly, a planetary gear reducer transmission assembly, a synchronous belt transmission assembly, a ball screw transmission assembly, a guide assembly, a housing, an end cap, and a slide plate structure. The drive component is a brake stepper motor, and its tail brake can achieve self-locking when power is off. The feedback component includes a position feedback sensor and limit switches; the position feedback sensor feeds back the slide position information to the control system in real time, thereby realizing closed-loop control of the stepper motor; the limit switches are distributed at the positive and negative limit positions of the slide, which can realize the electrical limit protection of the mechanism. The planetary gear reducer transmission assembly includes a planetary gear reducer and a reducer bracket; the planetary gear reducer is directly connected to the stepper motor and then fixed to the housing by the reducer bracket; the mounting interface of the planetary gear reducer on the reducer bracket is a slotted hole. The synchronous belt drive assembly includes a driving synchronous pulley, a driven synchronous pulley, and a synchronous belt; the driving and driven synchronous pulleys are respectively fixedly mounted on the output shaft of the planetary gear reducer and the input shaft of the ball screw using their own set screws; The ball screw transmission assembly includes a ball screw and its nut, a fixed-side support unit, and a supporting-side support unit. The fixed-side support unit and the supporting-side support unit are matching components for the ball screw, each containing two angular contact ball bearings and one deep groove ball bearing, which are fixed to corresponding holes on the housing and end cover with screws. The two ends of the ball screw are installed in the support unit, and the ball screw nut is fixed to the slide plate with screws, thereby converting the rotary motion of the stepper motor into the linear motion of the slide plate. The guide assembly consists of three identical linear bearing assemblies, which are parallel to each other and evenly distributed on the circumference. Each linear bearing assembly consists of two linear bearings and a light shaft. The two linear bearings are respectively installed in corresponding holes in the end cap and the housing, and are axially limited by a shaft retaining spring. The light shaft passes through the corresponding two linear bearings and is fixed to the slide plate by a shrink-fitting connecting sleeve. The mechanism is driven by a brake stepper motor with an integrated brake at the tail. The rotational motion of the brake stepper motor is transmitted to the ball screw through a planetary gear reducer and a synchronous belt. The ball screw then converts the rotational motion into linear motion and transmits it to the slide plate. The slide plate is guided by three sets of parallel linear bearing assemblies during its movement. The slide plate has threaded holes for mounting the target assembly; the position of the slide plate is fed back in real time by a grating ruler and a reading head, and the brake stepper motor is controlled in a closed loop; the grating ruler is a steel strip grating ruler, which is attached to the grating ruler base with its own adhesive backing, and the grating ruler base is fixed to the slide plate with screws; the reading head is fixed to the housing through a reading head adapter.

2. The mechanism according to claim 1, characterized in that, The slide plate is a moving part in the mechanism, and it has multiple sets of threaded holes as mechanical interfaces for mounting the carrier.

3. The mechanism according to claim 2, characterized in that, The housing and end cap are fixed together by screws and positioned by two internally threaded tapered pins, together forming the outer shell of the mechanism. The housing and end cap have mounting holes for the fixed-side support unit and the support-side support unit of the linear bearing and ball screw, as well as threaded holes for the reducer bracket, the reading head adapter seat and the limit switch. Mechanical interfaces are also reserved for connection with other components.

4. The mechanism according to claim 3, characterized in that, There is a limit switch at each of the positive and negative extreme positions of the slide plate. Together with the limit baffle installed on the slide plate, the electrical limit protection of the mechanism can be realized.

5. The mechanism according to claim 4, characterized in that, The brake stepper motor is fixed to the planetary gear reducer by screws, and its output shaft is tightened to the input shaft of the planetary gear reducer by the fastening screws provided with the planetary gear reducer. The planetary gear reducer is fixed to the reducer bracket by screws, and then the reducer bracket is fixed to the housing by screws. The mounting interface of the planetary gear reducer on the reducer bracket is a slotted hole, which facilitates the adjustment of the shaft spacing between the output shaft of the planetary gear reducer and the ball screw, thereby realizing the installation and tensioning of the synchronous belt. The reducer bracket and the housing are positioned by a "one-face, two-pin" method.

6. The mechanism according to claim 5, characterized in that, The ball screw is installed at both ends in the matching fixed-side support unit and the supporting-side support unit. The ball screw nut is fixed to the slide plate by screws. The fixed-side support unit and the supporting-side support unit are fixed to the end faces of the housing and the end cover by screws, respectively.

7. The mechanism according to claim 1, characterized in that, The selected expansion coupling sleeve is a type with a built-in nut, which can be used to firmly fix the optical axis and the slide plate by simply tightening the nut.

8. The mechanism according to claim 1, characterized in that, The housing and end cap are connected by screws, and the corresponding linear bearing mounting holes and ball screw support unit mounting holes are machined in combination, specifically: (1) Before assembly, the housing and end cap are positioned using two conical pins to ensure that their relative positions remain unchanged when disassembled and reassembled. (2) After positioning with a tapered pin, use a boring machine to machine the corresponding mounting holes at the same time.

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