A blind hole gear shaft marking fixture

Abstract

This utility model belongs to the field of marking fixture technology, specifically disclosing a blind hole gear shaft marking fixture, including a marking fixture body and a positioning pin. The marking fixture body has a central insertion hole and a pin hole on its end face, the pin hole being located outside the insertion hole. One end of the workpiece can be inserted into the insertion hole on the marking fixture body, and the pin hole and a weight-reducing hole on the workpiece are directly opposite each other. The positioning pin is sequentially inserted into the weight-reducing hole on the workpiece and the pin hole on the marking fixture body. This utility model can solve the problem of inaccurate marking positions caused by manual positioning of the workpiece.

Description

Technical Field

[0001] This utility model relates to the field of marking tooling technology, specifically to a blind hole gear shaft marking tooling. Background Technology

[0002] Currently, for hard turning the outer diameter or end face of disc-type shafts, the commonly used tooling design is a method of clamping the bearing outer diameter and positioning it with a center hole. In existing technology, the marking tooling used when marking workpieces with blind-hole gear shafts, such as... Figure 4 As shown, it includes a marking fixture base and a positioning plate. The marking fixture base is fixed on the positioning base plate. When in use, the marking fixture base needs to be fixed to the positioning base plate with screws. Then, the workpiece is placed on the marking fixture base and the workpiece is marked. The end face of the workpiece is provided with multiple circumferentially evenly distributed weight-reducing holes.

[0003] The following problems exist in the current tooling marking process:

[0004] 1. The marking fixture has no directional error prevention and the marking position cannot be fixed. The workpiece needs to be rotated manually to confirm the marking position, which can easily lead to inaccurate marking position.

[0005] 2. Foreign objects, such as small steel shot, are present in the blind holes of the workpiece. In the existing technology, the workpiece is usually cleaned manually with an air gun before the marking is carried out, which is inefficient. Utility Model Content

[0006] This utility model provides a blind hole gear shaft marking fixture, which aims to solve the problem of inaccurate marking position caused by manual positioning of the workpiece.

[0007] This utility model is achieved through the following technical solution: a blind hole gear shaft marking fixture, including a marking fixture body and a positioning pin, wherein an insertion hole is provided in the center of the marking fixture body, and a pin hole is provided on the end face of the marking fixture body, the pin hole being located outside the insertion hole; one end of the workpiece can be inserted into the insertion hole on the marking fixture body, and the pin hole and the weight reduction hole on the workpiece are arranged opposite to each other, and the positioning pin is inserted into the weight reduction hole on the workpiece and the pin hole on the marking fixture body in sequence.

[0008] Compared with existing technologies, this solution has the following advantages and beneficial effects:

[0009] In this solution, an insertion hole is made in the center of the marking fixture body to facilitate the installation of the workpiece. Since a pin hole is made on the end face of the marking fixture, after the workpiece is inserted into the insertion hole of the marking fixture body, a positioning pin is inserted into the weight reduction hole of the workpiece and the pin hole of the marking fixture body to position the workpiece. In this way, the marking position is designed in advance according to the marking position of the workpiece, and the positioning is achieved by positioning pin, thus eliminating the need for manual rotation positioning. Existing marking fixtures do not have positioning pins, and the marking position needs to be manually confirmed, which poses a risk of marking position error. This solution effectively solves the problem of inaccurate marking position caused by manual positioning of the workpiece marking position.

[0010] Compared to existing technologies, this solution effectively overcomes the shortcomings of marking fixtures, such as lack of directional error prevention and inconsistent marking positions. After the positioning pins are sequentially inserted into the weight-reduction holes on the workpiece and the pin holes on the marking fixture body, the installation angle and position of the workpiece can be precisely defined, avoiding positioning deviations caused by manual workpiece rotation. This significantly improves the accuracy and consistency of the marking position, ensuring that marking patterns, text, or codes are accurately placed in the preset positions, reducing scrap rates and meeting high-precision production requirements.

[0011] In terms of operational efficiency, the previous manual positioning of workpiece marking positions required repeated adjustments and confirmations, which was time-consuming. This solution, however, pre-designs the marking positions and uses positioning pins to quickly complete workpiece positioning, eliminating the tedious manual adjustment process, significantly shortening the preparation time before marking, greatly reducing the marking cycle time for a single workpiece, effectively improving production efficiency, and meeting the pace requirements of large-scale production.

[0012] This tooling has a simple structure and strong versatility. By simply changing the appropriate positioning pin and adjusting the size of the marking tooling body's insertion hole, it can be used for marking blind hole gear shafts of different specifications, effectively reducing the tooling investment cost for enterprises and improving the flexibility and economy of production.

[0013] Furthermore, it also includes an air nozzle and an air supply unit. The lower part of the air nozzle is coaxially connected to the marking fixture body, and the upper part of the air nozzle is inserted into the blind hole of the workpiece. An air blowing channel is formed at the center of the air nozzle along its axial direction, and the top of the air blowing channel extends through the top of the air nozzle. An air inlet is formed on the lower outer periphery of the air nozzle, which communicates with the air blowing channel. The air supply unit communicates with the air inlet.

[0014] Beneficial effects: In this solution, the air supply unit is added to the marking fixture body with an air nozzle and an air supply unit, forming a complete automated cleaning and positioning marking system, which can clean foreign objects from the product while marking.

[0015] The air nozzle is coaxially connected to the marking fixture body and extends deep into the blind hole of the workpiece. Through the structural design of the internal air channel and the outer peripheral air inlet, the high-pressure gas output from the air supply unit can be accurately introduced into the blind hole of the workpiece. Compared with traditional manual air gun cleaning, this design achieves directional and concentrated gas injection, which can generate a strong impact force instantly, quickly peeling off and removing small steel shot, debris and other impurities attached to the inner wall and bottom of the blind hole, improving cleaning efficiency several times. At the same time, it avoids blind spots caused by uneven angle and force during manual operation, ensuring consistent cleanliness of the blind hole.

[0016] From the perspective of marking quality assurance, the air nozzle deep-penetration cleaning method in blind holes allows for immediate cleaning after workpiece positioning, avoiding the reintroduction of impurities during handling and clamping as with traditional cleaning methods. Furthermore, the high-pressure gas creates a positive pressure environment within the blind hole, effectively suppressing the backflow of dust and debris generated during marking and preventing contamination of the marking area. This provides a clean environment for laser marking, mechanical engraving, and other processes, ensuring that marked patterns and text are clear, complete, and free from blurring, missing parts, and significantly improving product yield.

[0017] Furthermore, the air supply unit includes an air pipe and an air pipe connector, the air pipe and the air pipe connector are connected to each other, the marking fixture body is provided with an air intake channel communicating with the air inlet, and the air pipe connector is connected to the air intake channel.

[0018] Beneficial effects: In this solution, the air pipe is used to connect to the high-pressure air source, and the air pipe connector is easy to connect to the marking fixture body, so as to introduce the air source into the air blowing channel of the air nozzle to clean the blind hole of the workpiece. The air inlet channel can deliver the gas to the air inlet hole and enter the air blowing channel from the air inlet hole.

[0019] Furthermore, an annular groove is formed on the lower outer circumference of the air nozzle, the air supply unit communicates with the annular groove, and the air inlet is located inside the annular groove.

[0020] Beneficial effects: In this solution, an annular groove is opened on the lower outer circle of the air nozzle. The setting of the annular groove can reduce the manufacturing precision requirements. The air inlet does not need to be completely aligned and connected with the air supply unit. The gas generated by the air supply unit first enters the annular groove and diffuses, and then enters the blowing channel through the air inlet in the annular groove. The air supply unit only needs to be connected to the annular groove to allow the air source to enter the blowing channel from the air inlet and clean the blind hole of the workpiece.

[0021] The annular groove serves as an intermediate medium for gas transmission, allowing the high-pressure gas input from the gas supply unit to diffuse fully within it, creating a uniform pressure distribution. When gas enters the blowing channel through the inlet holes in the annular groove, it can be injected into the blind holes with a more stable and balanced pressure, avoiding uneven cleaning caused by excessively high or low local pressure.

[0022] Furthermore, a slag discharge groove is provided below the insertion hole and communicates with it. The two ends of the slag discharge groove extend through both sides of the marking tool body. A connecting hole is provided in the center of the slag discharge groove, and the lower part of the air nozzle is connected to the connecting hole.

[0023] Beneficial effects: The slag discharge trough in this design facilitates the collection of impurities blown out from the blind holes of the workpiece. Both ends of the trough penetrate to the sides of the marking fixture body, allowing for the easy removal of blown-off impurities and preventing them from remaining inside the fixture or re-adhering to the workpiece. It also allows operators to directly observe and clean accumulated impurities within the trough from the outside. When the slag discharge trough becomes clogged, it can be quickly cleared using a brush or compressed air through the openings on both sides.

[0024] In this design, the connecting hole in the center of the slag discharge trough is securely connected to the lower part of the air nozzle, providing additional mechanical support for the air nozzle while enabling gas transmission.

[0025] Furthermore, both sides of the slag discharge trough are provided with downward sloping surfaces.

[0026] Beneficial effects: The inclined surfaces on both sides of the slag discharge trough in this solution can guide the impurities in the slag discharge trough, making it easier and faster to clean the impurities in the slag discharge trough.

[0027] Furthermore, the nozzle includes a rod and a head coaxially connected, the diameter of the rod being smaller than the diameter of the head; the rod of the nozzle is inserted into a blind hole in the workpiece, and the head of the nozzle is connected to the marking fixture body; the position between the head and the rod of the nozzle is set as a tapered surface.

[0028] Beneficial effects: In this design, the rod of the air nozzle is easy to insert into the blind hole of the workpiece, while the head of the air nozzle is easy to connect with the marking fixture body. The position between the head and the rod of the air nozzle is set as a conical surface, which can guide the impurities that are blown off and prevent them from accumulating at the head of the air nozzle.

[0029] Furthermore, the marking fixture body includes an upper marking positioning seat and a lower marking positioning seat, which are coaxially and detachably connected.

[0030] Beneficial effects: The marking fixture body in this solution includes an upper marking positioning seat and a lower marking positioning seat, which are coaxial and detachably connected. This makes it easier to install and remove the air nozzle, making the installation process more flexible and convenient, and also makes it easier to manufacture the insertion hole and slag discharge groove in the later stage.

[0031] Furthermore, both the upper marking positioning seat and the lower marking positioning seat are provided with a plurality of circumferentially distributed screw holes, and a plurality of pin holes are provided, which are circumferentially distributed and staggered with the plurality of screw holes.

[0032] Beneficial effects: The multiple screw holes in this design facilitate the connection of the upper and lower marking positioning seats into a single unit by inserting fasteners (such as screws), making disassembly easy. The staggered arrangement of multiple screw holes and multiple pin holes ensures a stable connection between the upper and lower marking positioning seats while achieving precise positioning through the cooperation of the pin holes and pin shafts, effectively improving the positioning accuracy and stability of the marking fixture.

[0033] Furthermore, it also includes a positioning base plate, which has multiple positioning holes arranged in a rectangular array. The marking fixture body and the positioning base plate are detachably connected by fasteners, the bottom end of which can be inserted into the positioning holes.

[0034] Beneficial effects: This solution also includes a positioning base plate, and because the positioning base plate has multiple positioning holes arranged in a rectangular array, the marking fixture body can be installed at any position on the positioning base plate, providing diverse installation point options for the marking fixture body. By inserting fasteners into the positioning holes at different positions, the lateral and longitudinal positions of the marking fixture body on the positioning base plate can be precisely adjusted. This flexible positioning method can quickly adapt to the layout requirements of different marking equipment, or adjust the position of the marking station according to the production line, without redesigning the overall fixture structure. Attached Figure Description

[0035] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0036] Figure 1 This is a perspective view of an embodiment of a blind hole gear shaft marking fixture according to the present invention;

[0037] Figure 2 This is a longitudinal cross-sectional view of an embodiment of the blind hole gear shaft marking fixture of this utility model;

[0038] Figure 3 This is an exploded view of an embodiment of a blind hole gear shaft marking fixture according to the present invention;

[0039] Figure 4 A 3D view of the engraving tooling in the existing technology.

[0040] The attached diagram shows the markings and corresponding component names:

[0041] Positioning base plate 1, positioning hole 101;

[0042] The upper markings include positioning seat 2, pin hole 20, upper screw hole 21, and insertion hole 22;

[0043] 3. Locating pin; 4. Screw; 5. Workpiece;

[0044] Air nozzle 6, annular groove 60, air inlet 61, air blowing channel 62;

[0045] The subscripts indicate the positioning seat 7, the connecting hole 70, and the lower screw hole 71.

[0046] 8. Air pipe connector, 9. Air pipe, 10. Slag discharge trough, 11. Inclined surface, 12. Air inlet channel. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0048] The workpiece in this invention is a gear shaft workpiece with blind holes. The end of this workpiece is machined with multiple circumferentially evenly distributed weight-reducing holes, and the center of the workpiece is a blind hole with the opening of the blind hole located at the bottom end of the workpiece.

[0049] As one embodiment of this application, such as Figures 1-2 As shown, a blind hole gear shaft marking fixture is provided, including a marking fixture body and a locating pin 3, as shown. Figure 3 As shown, a central coaxial insertion hole 22 is provided on the center of the marking fixture body, and a pin hole 20 is provided on the end face of the marking fixture body. The pin hole 20 is located outside the insertion hole 22. One end of the workpiece 5 can be inserted into the insertion hole 22 on the marking fixture body, and the pin hole 20 and the weight reduction hole on the workpiece 5 are directly opposite each other. The positioning pin 3 is inserted into the weight reduction hole on the workpiece 5 and the pin hole 20 on the marking fixture body in sequence, thereby positioning the workpiece 5 and ensuring the accuracy of the marking position of the workpiece 5.

[0050] In one embodiment, such as Figure 2 As shown, a blind hole gear shaft marking fixture also includes an air nozzle 6 and an air supply unit. The lower part of the air nozzle 6 is coaxially connected to the marking fixture body, and the upper part of the air nozzle 6 is inserted into the blind hole of the workpiece 5, with a gap between the part of the air nozzle 6 inserted into the blind hole of the workpiece 5 and the blind hole. An air blowing channel 62 is provided at the center of the air nozzle 6 along its axial direction, and the top of the air blowing channel 62 passes through the top of the air nozzle 6. An air inlet 61 communicating with the air blowing channel 62 is provided on the lower outer periphery of the air nozzle 6. The air supply unit is connected to the air inlet 61.

[0051] In one embodiment, such as Figure 1 and Figure 2As shown, the air supply unit includes an air pipe 9 and an air pipe connector 8. The air pipe 9 and the air pipe connector 8 are interconnected and communicate with each other. The air pipe 9 and the air pipe connector 8 can be connected by thread or compression fitting. The end of the air pipe 9 away from the air pipe connector 8 is connected to a high-pressure air source, such as an air compressor.

[0052] like Figure 2 As shown, the marking fixture body has an air intake channel 12 that communicates with the air intake hole 61. In this embodiment, the air intake channel 12 is opened horizontally on the standard fixture body. The air pipe connector 8 is connected to the air intake channel 12. In this embodiment, the inner side of the air intake channel 12 has an internal thread, and the outer side of the air pipe connector 8 has an external thread. The air pipe connector 8 is threadedly connected to the air intake channel 12, which facilitates the installation and removal of the air pipe connector 8.

[0053] In one embodiment, such as Figure 1 , Figure 2 and Figure 3 As shown, the marking fixture body includes an upper marking positioning seat 2 and a lower marking positioning seat 7, which are coaxially and detachably connected.

[0054] Specifically: In this embodiment, both the upper marking positioning seat 2 and the lower marking positioning seat 7 are provided with multiple circumferentially evenly distributed screw holes, such as... Figure 3 As shown, the screw hole on the upper marked positioning seat 2 is the upper screw hole 21, and the screw hole on the lower marked positioning seat 7 is the lower screw hole 71. The upper screw hole 21 is a countersunk hole, which facilitates the concealment of the head of the screw 4 that is inserted later.

[0055] In this embodiment, there are four pin holes 20, which are evenly distributed circumferentially. There are also four upper screw holes 21 and four lower screw holes 71. The four upper screw holes 21 and the four lower screw holes 71 are arranged in sequence overlapping each other. The four screw holes and the four pin holes 20 are arranged alternately, that is, the four screw holes and the four pin holes are arranged circumferentially in a cross pattern. This makes the four screw holes and the four pin holes 20 arranged in a circle around the circumference of the marking fixture body.

[0056] After the upper marking positioning seat 2 and the lower marking positioning seat 7 overlap, fasteners (such as screws 4) are screwed into the upper screw hole 21 and the lower screw hole 71 to connect and fix the upper marking positioning seat 2 and the lower marking positioning seat 7.

[0057] In one embodiment, such as Figure 2As shown, the nozzle 6 includes a rod and a head connected coaxially. The rod and head are integrally formed, and the diameter of the rod is smaller than the diameter of the head. The rod of the nozzle 6 is inserted into the blind hole of the workpiece 5, and the head of the nozzle 6 is connected to the marking fixture body. The position between the head and the rod of the nozzle 6 is set as a conical surface, that is, the top of the head of the nozzle 6 forms a conical surface structure. This can guide impurities falling from the blind hole and prevent impurities from accumulating at the top of the head of the nozzle 6.

[0058] In one embodiment, such as Figure 2 and Figure 3 As shown, an annular groove 60 is formed on the lower outer circle of the air nozzle 6. In this embodiment, the annular groove 60 is formed on the outer circle of the head of the air nozzle 6. The annular groove 60 forms a closed cavity with the inner side of the marking fixture body. The air supply unit communicates with the annular groove 60. The air inlet 61 is located in the annular groove 60. In this embodiment, two or more air inlets 61 are provided, and the air inlets 61 are evenly distributed around the circumference of the air nozzle 6.

[0059] The air intake channel 12 is connected to the annular groove 60, so that the air supply unit can communicate with the annular groove 60 through the air intake channel 12. The air source enters the annular groove 60 through the air intake channel 12 and diffuses, and then enters the blowing channel 62 through the air intake hole 61. This simplifies the connection between the air supply unit and the air intake hole 61.

[0060] In one embodiment, such as Figure 1 , Figure 2 and Figure 3 As shown, a slag discharge groove 10 communicating with the insertion hole 22 is provided below it. In this embodiment, the insertion hole 22 is located on the upper marking positioning seat 2, and the slag discharge groove 10 is located on the lower marking positioning seat 7. Figure 3 As shown, the two ends of the slag discharge trough 10 pass through both sides of the marking tool body, thus forming a through-groove structure. A connecting hole 70 is provided in the center of the slag discharge trough 10, and the lower part of the air nozzle 6 is connected to the connecting hole 70.

[0061] In one embodiment, the head of the air nozzle 6 is provided with an external thread, and the connecting hole 70 in the center of the slag discharge groove 10 is provided with an internal thread. The head of the air nozzle 6 is threadedly connected to the connecting hole 70, thereby realizing the detachable connection between the air nozzle 6 and the lower marking positioning seat 7 of the marking fixture body.

[0062] like Figure 2 As shown, the annular groove 60 on the head of the nozzle 6 is located inside the connecting hole 70, forming a closed space with the connecting hole 70, which allows the air source to enter the blowing channel 62 from the air inlet 61.

[0063] In one embodiment, such as Figure 3 As shown, both sides of the slag discharge trough 10 are provided with downward sloping surfaces 11, which makes it easier to discharge impurities from the slag discharge trough 10.

[0064] In one embodiment, such as Figure 1 As shown, a blind hole gear shaft marking fixture also includes a positioning base plate 1. The positioning base plate 1 has multiple positioning holes 101, which are distributed in a rectangular array. The marking fixture body and the positioning base plate 1 are detachably connected by fasteners. The bottom end of the fastener can be inserted into the positioning hole 101. Specifically, in this embodiment, the fastener is a screw 4. By screwing the screw 4 into the screw hole of the marking fixture body, and the screw 4 passing through the bottom of the marking fixture body and being inserted into the corresponding positioning hole 101 on the positioning base plate 1, the marking fixture body is installed and positioned on the positioning base plate 1.

[0065] In actual installation, the marking fixture body can be installed at any position on the positioning base plate 1 according to actual needs, making installation flexible and convenient.

[0066] The specific implementation process is as follows:

[0067] One end of the workpiece 5 is inserted into the insertion hole 22 in the center of the marking fixture body, and at the same time, the rod of the air nozzle 6 is inserted into the blind hole of the workpiece 5. Then, two positioning pins 3 are inserted into the weight reduction hole of the workpiece 5 and the pin hole 20 on the marking fixture body in sequence to achieve the positioning of the workpiece 5. The workpiece 5 can be positioned at the marking position without manual rotation.

[0068] Connect air tube 9 to the air source. The air flow path is as follows: Figure 2 As shown by the arrow, the gas blows out high-pressure gas through the air blowing channel 62, blowing out the impurities remaining in the blind hole of the workpiece 5 and dropping them into the slag discharge tank 10. In this way, while the marking is completed, the impurities remaining inside the workpiece 5 are also blown clean, effectively reducing manual input and labor intensity.

[0069] It should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A blind hole pinion marking tool characterized by, The tooling includes a marking fixture body and a positioning pin. The marking fixture body has a central insertion hole and a pin hole on its end face. The pin hole is located outside the insertion hole. One end of the workpiece can be inserted into the insertion hole on the marking fixture body, and the pin hole and the weight reduction hole on the workpiece are directly opposite each other. The positioning pin is inserted into the weight reduction hole on the workpiece and the pin hole on the marking fixture body in sequence.

2. A blind hole pinion marking tool according to claim 1, wherein It also includes an air nozzle and an air supply unit. The lower part of the air nozzle is coaxially connected to the marking fixture body, and the upper part of the air nozzle is inserted into the blind hole of the workpiece. An air blowing channel is opened at the center of the air nozzle along its axial direction, and the top of the air blowing channel passes through the top of the air nozzle. An air inlet is opened on the lower outer periphery of the air nozzle, which communicates with the air blowing channel. The air supply unit communicates with the air inlet.

3. The blind hole gear shaft marking fixture according to claim 2, characterized in that, The air supply unit includes an air pipe and an air pipe connector. The air pipe and the air pipe connector are connected to each other. The marking fixture body has an air intake channel that communicates with the air inlet. The air pipe connector is connected to the air intake channel.

4. A blind hole gear shaft marking fixture according to claim 2 or 3, characterized in that, A ring groove is formed on the lower outer circle of the air nozzle, the air supply unit communicates with the ring groove, and the air inlet is located inside the ring groove.

5. A blind hole gear shaft marking fixture according to claim 2 or 3, characterized in that, A slag discharge groove is provided below the insertion hole and communicates with it. The two ends of the slag discharge groove pass through the two sides of the marking tool body. A connecting hole is provided in the center of the slag discharge groove, and the lower part of the air nozzle is connected to the connecting hole.

6. The blind hole gear shaft marking fixture according to claim 5, characterized in that, Both sides of the slag discharge trough are provided with downward sloping surfaces.

7. The blind hole gear shaft marking fixture according to claim 2, characterized in that, The nozzle includes a rod and a head connected coaxially, the diameter of the rod being smaller than the diameter of the head; the rod of the nozzle is inserted into a blind hole in the workpiece, and the head of the nozzle is connected to the marking fixture body; the position between the head and the rod of the nozzle is set as a tapered surface.

8. The blind hole gear shaft marking fixture according to claim 2, characterized in that, The marking fixture body includes an upper marking positioning seat and a lower marking positioning seat, which are coaxially and detachably connected.

9. A blind hole gear shaft marking fixture according to claim 8, characterized in that, Both the upper marking positioning seat and the lower marking positioning seat are provided with multiple circumferentially distributed screw holes, and multiple pin holes are provided. The multiple pin holes are circumferentially distributed, and the multiple screw holes and the multiple pin holes are staggered and spaced apart.

10. The blind hole gear shaft marking fixture according to claim 1, characterized in that, It also includes a positioning base plate, which has multiple positioning holes arranged in a rectangular array. The marking fixture body and the positioning base plate are detachably connected by fasteners, and the bottom end of the fasteners can be inserted into the positioning holes.

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