Processing technology of deep blind arc step hole

Abstract

This invention relates to a machining process for a deep blind arc-shaped stepped hole structure, typically with a maximum depth not exceeding 2000 mm. The hole's shape consists of a bottom plane connected to an arc, a taper connecting to a straight section of the inner hole, and a stepped hole transitioning through a large arc. The machining process involves using a deep hole drilling and boring machine and forming tools to machine the arc-shaped stepped hole in segments, eliminating the need for a CNC lathe and vibration-damping tool holders. Each arc-shaped hole segment, depending on its diameter, has a 3-4 mm allowance on one side. Multiple stepped holes are drilled and boring. After drilling and boring, the forming tool body and forming tools are replaced to machine the arc-shaped hole. This process is repeated to complete the machining of other arc-shaped holes while ensuring the required depth. This machining method utilizes the large cutting volume of a deep hole drilling and boring machine, significantly shortening the machining cycle. The tools and fixtures are simple to use, the machining process is easy to control, ensuring product quality and improving machining efficiency, thus meeting the requirements for mass production of such products.

Description

Technical Field

[0001] This invention belongs to the field of mechanical manufacturing technology and relates to a processing technology for deep blind arc stepped holes using a deep hole drilling and boring machine. The maximum depth does not exceed 2000mm. The shape is a deep blind arc stepped hole structure in which the bottom plane of the hole is connected to the arc, the taper is connected to the straight section of the inner hole, and the stepped hole is connected by a large arc transition. Background Technology

[0002] This type of deep blind hole shell product requires extremely high strength, toughness, and machining precision. Its typical structure is a deep blind arc-shaped stepped hole, with the deepest segment generally not exceeding 2000mm. The shape is characterized by a bottom plane connecting to an arc, a taper connecting to the straight section of the inner hole, and a stepped hole transitioning through a large arc. Dimensional accuracy is generally 0.2mm, and surface roughness Ra≤6.3μm. Current machining methods involve pre-drilling and boring multiple stepped holes on a deep hole drilling and boring machine according to the diameter allowance of the arc-shaped stepped hole. Then, on a CNC lathe, an extended and damped tool holder is used to flatten the bottom and machine the various arc-shaped steps. This method using an extended and damped tool holder suffers from small machining depth and slow processing speed, while also increasing the occupation and investment of the CNC lathe and the damped tool holder. This method is suitable for production and processing during the research and development stage but not for mass production. Therefore, a reasonable machining process needs to be designed to adapt to the mass production of the product, achieving cost reduction and efficiency improvement. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a machining process for deep blind arc stepped holes that no longer uses CNC lathes and vibration damping tool holders for precision machining, but instead uses deep hole drilling and boring machines and forming tools to process the arc stepped holes in sections, thereby meeting the design requirements of the warhead shell and achieving cost reduction and efficiency improvement.

[0004] The objective of this invention is achieved as follows: a machining process for deep blind arc-shaped stepped holes. Since the arc-shaped stepped hole comprises two arc-shaped holes connected by a straight hole, the two arc-shaped holes are machined in segments. Each arc-shaped hole, based on its diameter and the machining range of the boring tool, is drilled and bored to create multiple stepped holes with a 3-4mm allowance on each side. After drilling and boring, the forming tool and forming cutter are replaced to machine the arc-shaped hole while ensuring the required depth. The specific machining process is as follows: Step 1) Machining the first section of deep blind arc flat-bottom hole: Step 1.1) Mount one end of the product onto the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the runout between the chuck and the rest position within 0.1mm. Drill the pilot hole Φd at a spindle speed of 70r / min, a drill rod speed of 220r / min, and a feed rate of 40±10mm / min, ensuring a hole depth L1 including the drill tip. Replace the reamer and sequentially ream the stepped holes Φd1 and Φd2 at a spindle speed of 70r / min and a drill rod speed of 20r / min. Feed rate 40-50 mm / min, ensuring hole depths L2 and L3 for the two steps of reaming; Replace the boring tool body, bore Φd3, Φd4, and Φd5 in sequence, lock the drill rod, spindle speed 60 r / min, feed rate 20-30 mm / min, ensuring corresponding hole depths L4, L5, and L6; Replace the floating boring tool body, repair the surface finish of the Φd5 inner hole, lock the drill rod, spindle speed 143 r / min, feed rate 20-30 mm / min, ensuring hole depth L6; Step 1.2) Place the product on the lathe, use the inner hole Φd5 as the reference for alignment, and machine the alignment frame position of the solid end spindle and the center frame position of the open end to ensure that the coaxiality at the frame position is ≤0.05mm; Step 1.3) Mount one end of the product into the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the runout between the chuck and the center rest position within 0.05mm. Install the forming cutter body and 3 forming cutters on the boring bar, align the gap between the forming cutters and the hole wall to ensure centering, lock the drill rod, set the spindle speed to 50-60r / min, and the feed rate to 5mm / min. After the wooden guide key on the forming cutter body is completely inserted into the hole, feed to a depth of (L1-60)mm, and adjust the feed rate to 3mm / min. After the forming cutter has made contact with the hole, adjust the feed rate to 2mm / min. Observe the shape of the chips and the vibration of the tool bar and adjust the feed rate accordingly. After the forming cutter has completely removed the internal hole steps, retract the tool to check the wear of the forming tool. Sharpen or replace the tool with a new one, and then feed back to the cutting position, adjusting the feed rate to 1mm / min. Machining to the required depth L, then retract the tool. Step 2), Machining the second section of the deep blind arc hole: Step 2.1) After the first section of deep blind arc flat bottom hole is machined, there is no need to remove the machine. Replace the boring bar and boring tool body, and bore Φd6, Φd7, and Φd8 in sequence. The spindle speed is 60 r / min and the feed rate is 20-30 mm / min to ensure the corresponding hole depths L7, L8, and L9. Replace the floating boring tool body, repair the surface finish of the Φd8 inner hole, lock the drill rod, and set the spindle speed to 143 r / min and the feed rate to 20-30 mm / min to ensure the hole depth L9. Step 2.2) Place the product on the lathe, align it with the inner hole Φd8 as the reference, and adjust the alignment position of the solid end spindle and the center position of the open end to ensure that the coaxiality at the position is ≤0.05mm. Step 2.3) Mount one end of the product into the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the chuck position with the center rest position, ensuring the runout is within 0.05mm. Following the machining parameters and steps of the forming tool and forming cutter for the first section of the arc-shaped flat-bottomed hole, form the inner cavity of the second section of the deep blind arc-shaped hole. Use a special device for measuring the depth of the inner hole arc-shaped taper transition section to measure the depth of the second section of the arc-shaped hole, ensuring the depth L of the second section of the arc-shaped hole is accurate. 10 .

[0005] This invention uses a deep hole drilling and boring machine. Through reasonable process design, it can machine deep blind flat bottom arc stepped holes without using CNC lathes and vibration damping tool holders, reducing the occupation of CNC equipment and saving 6 hours of processing time in this case. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of an example of the deep blind flat-bottomed arc-shaped stepped hole of the present invention.

[0007] Note: Typical features of the example: First section deep blind flat-bottomed arc hole depth L=1282mm; Second section arc hole depth L 10 =1113mm and maximum hole diameter Φd8=206mm, and straight hole Φd9=143mm in the two-section arc inner control transition section.

[0008] Figure 2 This is a schematic diagram of the first stage of drilling a stepped hole for a deep blind flat-bottomed arc hole according to the present invention.

[0009] Note: To reduce the depth of cut of the first-stage deep blind flat-bottomed arc hole forming tool, prefabricate stepped holes from Φd1 to Φd5, with a machining allowance of 3-4mm on each side; bore and float bore to form a straight hole Φd6 = 146mm, which serves as the machining reference for the first-stage arc hole forming tool.

[0010] Figure 3 This is a schematic diagram of the inner cavity forming of the first deep blind flat-bottomed arc hole of the present invention.

[0011] Note: The first section of deep blind flat-bottomed arc hole was machined using a forming tool, ensuring a depth of L=1282mm, and a straight hole Φd9=143mm was bored into the two arc transition sections.

[0012] Figure 4 This is a schematic diagram of the drilling process for the second deep blind arc hole of the present invention.

[0013] Note: To reduce the depth of cut of the second-stage arc hole forming tool, a stepped hole from Φd6 to Φd8 is prefabricated, with a machining allowance of 3-4mm on each side; the straight hole Φd8=206mm is bored and float-bored, serving as the machining reference for the second-stage arc hole forming tool, and also as the final inner diameter dimension.

[0014] Figure 5 This is a schematic diagram of the first section of the deep blind flat-bottomed arc hole forming tool body and tool of the present invention.

[0015] Figure 6 This is a schematic diagram of the second-section deep blind arc hole forming tool body and tool of the present invention. Detailed Implementation

[0016] Example 1: This invention discloses a processing method for a deep blind flat-bottomed arc-shaped stepped hole product: The typical feature is that the inner hole is a deep blind flat-bottomed arc-shaped stepped hole, its shape being that the bottom plane of the hole connects to an arc, the taper connects to the straight section of the inner hole, and the stepped hole is connected by a large arc transition. The first section of the deep blind flat-bottomed arc-shaped hole has a depth L = 1282 mm, and the second section of the arc-shaped hole has a depth L... 10 =1113mm, the straight hole Φd9 =143mm in the transition section between the two sections of circular 4-arc inner holes, and the maximum hole diameter in the example Φd8 =206mm. Since the circular arc stepped hole contains two circular arc holes and the two circular arc holes are connected by a straight hole, the two circular arc holes are machined in sections. Each circular arc hole is drilled and bored to form multiple stepped holes with a 3-4mm allowance on one side, depending on the hole diameter and the machining range of the boring tool. After drilling and boring, the forming tool and forming cutter are replaced to machine the circular arc hole into shape and ensure the depth requirement. The specific machining process is as follows: Step 1), as Figure 2 , Figure 3 , Figure 5 Machining of the first deep blind arc-shaped flat-bottomed hole: Step 1.1) Mount one end of the product onto the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the runout between the chuck and the rest position within 0.1mm. Drill the pilot hole Φd at a spindle speed of 70r / min, a drill rod speed of 220r / min, and a feed rate of 40±10mm / min, ensuring a hole depth L1 including the drill tip. Replace the reamer and sequentially ream the stepped holes Φd1 and Φd2 at a spindle speed of 70r / min and a drill rod speed of 20r / min. Feed rate 40-50 mm / min, ensuring hole depths L2 and L3 for the two steps of reaming; Replace the boring tool body, bore Φd3, Φd4, and Φd5 in sequence, lock the drill rod, spindle speed 60 r / min, feed rate 20-30 mm / min, ensuring corresponding hole depths L4, L5, and L6; Replace the floating boring tool body, repair the surface finish of the Φd5 inner hole, lock the drill rod, spindle speed 143 r / min, feed rate 20-30 mm / min, ensuring hole depth L6; Step 1.2) Place the product on the lathe, use the inner hole Φd5 as the reference for alignment, and machine the alignment frame position of the solid end spindle and the center frame position of the open end to ensure that the coaxiality at the frame position is ≤0.05mm; Step 1.3) Mount one end of the product into the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the runout between the chuck and the center rest position within 0.05mm. Install the forming cutter body and forming insert on the boring bar, align the gap between the forming insert and the hole wall to ensure centering, lock the drill rod, set the spindle speed to 50-60 r / min, and the feed rate to 5 mm / min. After the wooden guide key on the forming cutter body is completely inserted into the hole, feed to a depth of (L1-60) mm, and adjust the feed rate to 3 mm / min. After the forming cutter has made contact with the hole, adjust the feed rate to 2 mm / min. Observe the shape of the chips and the vibration of the tool bar and adjust the feed rate accordingly. After the forming cutter has completely removed the internal hole steps, retract the tool to check the wear of the forming tool. Sharpen or replace the tool, and then feed back to the cutting position, adjusting the feed rate to 1 mm / min. Machining to the required depth L, then retract the tool. Step 2), as Figure 4 , Figure 1 , Figure 6 Machining of the second deep blind arc hole: Step 2.1) After the first section of deep blind arc flat bottom hole is machined, there is no need to remove the machine. Replace the boring bar and boring tool body, and bore Φd6, Φd7, and Φd8 in sequence. The spindle speed is 60 r / min and the feed rate is 20-30 mm / min to ensure the corresponding hole depths L7, L8, and L9. Replace the floating boring tool body, repair the surface finish of the Φd8 inner hole, lock the drill rod, and set the spindle speed to 143 r / min and the feed rate to 20-30 mm / min to ensure the hole depth L9. Step 2.2) Mount the product on the lathe, using the inner hole Φd8 as a reference for alignment, and adjust the alignment position of the solid end spindle and the open end. The center frame position should be maintained with a coaxiality of ≤0.05mm. Step 2.3) Mount one end of the product into the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the chuck position with the center rest position, ensuring the runout is within 0.05mm. Following the machining parameters and steps of the forming tool and forming cutter for the first section of the arc-shaped flat-bottomed hole, form the inner cavity of the second section of the deep blind arc-shaped hole. Use a special device for measuring the depth of the inner hole arc-shaped taper transition section to measure the depth of the second section of the arc-shaped hole, ensuring the depth L of the second section of the arc-shaped hole is accurate. 10 .

[0017] According to the above implementation method, without CNC lathes and vibration damping tool holders, the machining of deep blind flat bottom arc stepped holes was successfully completed on a deep hole drilling and boring machine, and the dimensional accuracy requirements were met.

Claims

1. A machining process for a deep blind arc-shaped stepped hole, characterized in that: Because the arc-shaped stepped hole consists of two arc-shaped holes connected by a straight hole, the two arc-shaped holes are machined separately. Each arc-shaped hole is drilled and bored to create multiple stepped holes, with a 3-4mm allowance on each side, depending on the hole diameter and the machining range of the boring tool. After drilling and boring, the forming tool and forming cutter are replaced to machine the arc-shaped hole and ensure the required depth. The specific machining process is as follows: Step 1) Machining the first section of deep blind arc flat-bottom hole: Step 1.1) Mount one end of the product onto the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the runout between the chuck and the rest position within 0.1mm. Drill the pilot hole Φd at a spindle speed of 70r / min, a drill rod speed of 220r / min, and a feed rate of 40±10mm / min, ensuring a hole depth L1 including the drill tip. Replace the reamer and sequentially ream the stepped holes Φd1 and Φd2 at a spindle speed of 70r / min and a drill rod speed of 20r / min. Feed rate 40-50 mm / min, ensuring hole depths L2 and L3 for the two steps of reaming; Replace the boring tool body, bore Φd3, Φd4, and Φd5 in sequence, lock the drill rod, spindle speed 60 r / min, feed rate 20-30 mm / min, ensuring corresponding hole depths L4, L5, and L6; Replace the floating boring tool body, repair the surface finish of the Φd5 inner hole, lock the drill rod, spindle speed 143 r / min, feed rate 20-30 mm / min, ensuring hole depth L6; Step 1.2) Place the product on the lathe, use the inner hole Φd5 as the reference for alignment, and machine the alignment frame position of the solid end spindle and the center frame position of the open end to ensure that the coaxiality at the frame position is ≤0.05mm; Step 1.3) Mount one end of the product into the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the runout between the chuck and the center rest position within 0.05mm. Install the forming cutter body and forming insert on the boring bar, align the gap between the forming insert and the hole wall to ensure centering, lock the drill rod, set the spindle speed to 50~60r / min, and the feed rate to 5mm / min. After the wooden guide key on the forming cutter body is completely inserted into the hole, feed to a depth of (L1-60)mm, and adjust the feed rate to 3mm / min. After the forming cutter enters the hole, adjust the feed rate to 2mm / min. Observe the shape of the chips and the vibration of the tool bar and adjust the feed rate in time. After the forming cutter has completely removed the steps in the inner hole, retract the tool to check the wear of the forming tool. Sharpen or replace the tool and feed back to the cutting position, adjusting the feed rate to 1mm / min. Machining to the required depth L, then retract the tool. Step 2), Machining the second section of the deep blind arc hole: Step 2.1) After the first section of deep blind arc flat bottom hole is machined, there is no need to remove the machine. Replace the boring bar and boring tool body, and bore Φd6, Φd7, and Φd8 in sequence. The spindle speed is 60 r / min and the feed rate is 20-30 mm / min to ensure the corresponding hole depths L7, L8, and L9. Replace the floating boring tool body, repair the surface finish of the Φd8 inner hole, lock the drill rod, and set the spindle speed to 143 r / min and the feed rate to 20-30 mm / min to ensure the hole depth L9. Step 2.2) Place the product on the lathe, align it with the inner hole Φd8 as the reference, and adjust the alignment position of the solid end spindle and the center position of the open end to ensure that the coaxiality at the position is ≤0.05mm. Step 2.3) Mount one end of the product into the chuck of the deep hole drilling and boring machine, and the other end onto the center rest, placing it on the pre-machined rest position on the product. Align the chuck position with the center rest position, ensuring the runout is within 0.05mm. Following the machining parameters and steps of the forming tool and forming cutter for the first section of the arc-shaped flat-bottomed hole, form the inner cavity of the second section of the deep blind arc-shaped hole. Use a special device for measuring the depth of the inner hole arc-shaped taper transition section to measure the depth of the second section of the arc-shaped hole, ensuring the depth L of the second section of the arc-shaped hole is accurate. 10 .

Images