A processing technology for the ball head cold holes of a die-casting module

Abstract

The present invention discloses a processing technology for the ball head cooling holes of a die-casting module, belonging to the field of hole processing technology for numerical control machine tools. The processing technology includes: first determining the parameters of the cooling holes of the die-casting module, then machining a pilot hole, then feeding an internal cooling drill bit into the pilot hole and making the internal cooling drill bit discharge water, then using the internal cooling drill bit to machine the cooling holes, then feeding an internal cooling ball head drill into the cooling holes and making the internal cooling ball head drill discharge water, and finally using the internal cooling ball head drill to perform point machining on the bottom of the cooling holes. By using the internal cooling drill bit to quickly machine the cooling holes and then cooperating with the point machining of the internal cooling ball head drill on the bottom of the cooling holes, the present invention can avoid the appearance of edges and corners at the bottom of the cooling holes of the existing die-casting molds and surface machining damage of the hole walls, and significantly improves the processing efficiency compared with the existing electrical discharge machining method.

Description

Technical Field

[0001] The present invention belongs to the field of hole machining processes for numerically controlled machine tools, and specifically relates to a ball head point cooling hole machining process for die-casting modules. Background Art

[0002] With the emergence of large integrated die-casting, large-tonnage die-casting molds are currently in a stage of rapid development. Due to the diversity of product sizes and complexities, especially for deep point cooling holes on the mold where the depth exceeds 25 times the hole diameter, it is difficult to ensure the machining difficulty and accuracy. As a result, there are corners near the bottom of the point cooling holes on large-tonnage die-casting molds and machining damage on the hole wall surface. The resulting corners and machining damage can cause stress corrosion and cracking.

[0003] To solve the above problems, the prior art usually uses electrical discharge machining to machine point cooling holes. However, due to the high hardness of the mold, this machining method has the problem of low machining efficiency and cannot meet the production requirements. Summary of the Invention

[0004] Object of the Invention: To provide a point cooling hole machining process that can eliminate the machining corners near the bottom of the point cooling holes and machining damage on the hole wall surface, and at the same time improve the machining efficiency.

[0005] The technical solution of the present invention is as follows: A ball head point cooling hole machining process for die-casting modules includes: S1. Determine the hole depth L and hole diameter D of the point cooling holes in the die-casting module.

[0006] S2. The machine tool machines a pilot hole on the die-casting module according to the hole diameter.

[0007] S3. The machine tool feeds the internal cooling drill bit into the pilot hole and makes the internal cooling drill bit discharge water when the internal cooling drill bit reaches a predetermined position in the pilot hole.

[0008] S4. The machine tool drives the internal cooling drill bit to machine a point cooling hole with a hole depth of L.

[0009] S5. When the internal cooling drill bit machines a point cooling hole with a hole depth of L, make the internal cooling drill bit pause for a predetermined time, and then retract the internal cooling drill bit to the safety plane.

[0010] S6. When the machine tool feeds the internal cooling ball head drill to a predetermined position of the point cooling hole with a hole depth of L, make the internal cooling ball head drill discharge water.

[0011] S7. The machine tool drives the internal cooling ball head drill to machine the bottom of the point cooling hole by point machining.

[0012] S8. Make the internal cooling ball head drill pause for a predetermined time, and then retract the internal cooling ball head drill to the safety plane.

[0013] In a further embodiment, in S2, the machine tool uses a milling cutter to mill a guiding hole, and the depth of the guiding hole is 3 to 4 times the hole diameter D. Through milling, there is no specific requirement for the hole surface, and a flat surface, a curved surface, an inclined surface or an irregular surface can all be used as the hole surface.

[0014] In a further embodiment, the accuracy grades of the internal coolant drill bit and the internal coolant ball nose drill are H6 and above. By using the internal coolant drill bit and the internal coolant ball nose drill with accuracy grades of H6 and above, the clamping accuracy of the drill bit can be effectively guaranteed.

[0015] In a further embodiment, in S3, S4, S6 and S7, the water outlet pressure of the internal coolant drill bit and the internal coolant ball nose drill is between 10 bar and 50 bar. During machining, the internal spray pressure is used to carry out the chips and heat generated during the cutting process, and the problem of cooling during internal hole machining can also be solved.

[0016] In a further embodiment, in S5 and S8, the pause time of the internal coolant drill bit and the internal coolant ball nose drill is between 0.2 and 0.4 seconds, which can prevent the problem that the rotational speed has not completely decreased and the high-pressure internal spray has not completely closed when the machine tool retracts, resulting in an increase in tool swing, thereby affecting the machining accuracy and tool life.

[0017] In a further embodiment, in S6, when the internal coolant ball nose drill feeds to the depth position of L - [(D / 2) + 1] of the point cooling hole, the internal coolant ball nose drill discharges water, which can avoid the problem that the machining accuracy is reduced due to the tool tremor caused by the water flow reaction force while ensuring the machining efficiency.

[0018] In a further embodiment, in S7, the jogging machining amount of the internal coolant ball nose drill for point machining is 0.5 to 1% of the hole diameter D, and the jogging retraction amount is 2.5 to 3.5 times the jogging machining amount. Jogging machining can effectively solve the problem that there is no cutting edge at the bottom of the ball nose and can machine the ball nose at the bottom of the hole.

[0019] In a further embodiment, in S4, the machine tool drives the internal coolant drill bit to machine a point cooling hole in a working state where the spindle speed is greater than that in S3 and the cutting feed is less than that in S3.

[0020] In S7, the machine tool drives the internal coolant ball nose drill to machine the bottom of the point cooling hole by point machining in a working state where the spindle speed is greater than that in S6 and the cutting feed is less than that in S7. Increasing the speed during cutting and decreasing the speed during retraction prevent the problem that the centrifugal force caused by the high-speed rotation during the idle cutting of the drill bit will increase the tool swing, thereby affecting the machining accuracy and tool life.

[0021] The beneficial effects of the present invention are as follows: By using an internally cooled drill bit, the present application can quickly machine a spot-cooled hole with a hole depth L and a hole diameter D, and then cooperate with the jogging of an internally cooled ball-end drill to machine the bottom of the spot-cooled hole, which can avoid the appearance of edges and corners at the bottom of the spot-cooled hole of the existing die-casting mold and the machining damage on the surface of the hole wall. Compared with the existing electrical discharge machining method, the machining efficiency is significantly improved.

[0022] The pilot hole can guide the internally cooled drill bit, enabling both the internally cooled drill bit and the internally cooled ball-end drill to rotate in the hole, avoiding the problem of reduced deep-hole positioning accuracy caused by the increased tool swing during the rotation of the internally cooled drill bit and the internally cooled ball-end drill, and ensuring the positioning accuracy of the deep hole.

[0023] After feeding the internally cooled drill bit and the internally cooled ball-end drill to a predetermined position in the hole and then discharging water, while cooling the cutting process, it can avoid the problem of reduced machining accuracy caused by the tool tremor due to the water flow reaction force, and ensure the machining accuracy of the bottom and the hole wall of the deep hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the working process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] In the following description, numerous specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, some well-known technical features are not described to avoid confusion with the present invention.

[0026] The present application discloses a spot-cooled hole machining process that can eliminate the machining corners near the bottom of the spot-cooled hole and the machining damage on the surface of the hole wall, and can improve the machining efficiency at the same time.

[0027] The machining process includes: S1. Determine the hole depth L and the hole diameter D of the spot-cooled hole of the die-casting module.

[0028] S2. The machine tool machines a pilot hole on the die-casting module according to the hole diameter.

[0029] S3. The machine tool feeds the internally cooled drill bit into the pilot hole and makes the internally cooled drill bit discharge water when the internally cooled drill bit reaches a predetermined position in the pilot hole.

[0030] S4. The machine tool drives the internally cooled drill bit to machine a spot-cooled hole with a hole depth L.

[0031] S5. When the internally cooled drill bit machines a spot-cooled hole with a hole depth L, pause the internally cooled drill bit for a predetermined time, and then retract the internally cooled drill bit to the safety plane.

[0032] When the internal coolant ball nose drill of the machine tool feeds to the predetermined position of the point-cooled hole at the hole depth L, the internal coolant ball nose drill discharges water.

[0033] S7. The machine tool drives the internal coolant ball nose drill to process the bottom of the point-cooled hole by point machining, and processes the bottom of the point-cooled hole into the bottom of the ball nose.

[0034] S8. Pause the internal coolant ball nose drill for a predetermined time, and then retract the internal coolant ball nose drill to the safety plane.

[0035] Thus, the processing of a single ball nose point-cooled hole is completed.

[0036] In this embodiment, the machine tool can be a machining center, or a combination of multiple different milling machines and drill presses, and the machine tool needs to have a high-pressure internal coolant center system.

[0037] In S5 and S8 of this embodiment, the predetermined pause time of the internal coolant drill bit and the internal coolant ball nose drill refers to pausing operations such as rotation, feeding, and water discharge.

[0038] In this embodiment, the internal coolant drill bit is a carbide drill bit with internal coolant, and the internal coolant ball nose drill is a carbide ball nose drill with internal coolant.

[0039] This application can quickly machine a point-cooled hole with a hole depth L and a hole diameter D by using an internal coolant drill bit, and then cooperate with the point machining of the internal coolant ball nose drill on the bottom of the point-cooled hole, which can avoid the appearance of edges and corners at the bottom of the point-cooled hole of the existing die-casting mold and machining damage to the hole wall surface, and significantly improve the machining efficiency compared with the existing electrical discharge machining method.

[0040] The internal coolant drill bit can be guided through the pilot hole, so that both the internal coolant drill bit and the internal coolant ball nose drill can rotate in the hole, avoiding the problem of reduced deep hole positioning accuracy caused by the increased tool swing during the rotation of the internal coolant drill bit and the internal coolant ball nose drill, and ensuring the deep hole positioning accuracy.

[0041] By discharging water after feeding the internal coolant drill bit and the internal coolant ball nose drill to the predetermined position in the hole, while cooling the cutting process, it can avoid the problem of reduced machining accuracy caused by the tool tremor due to the water flow reaction force, and ensure the machining accuracy of the bottom and the hole wall of the deep hole.

[0042] In a further embodiment, in S2, the machine tool uses a milling cutter to mill a pilot hole, and the depth of the pilot hole is 3 to 4 times the hole diameter D.

[0043] Through milling, there is no specific requirement for the hole surface. The plane, curved surface, inclined surface or irregular surface can all be used as the hole surface, improving the versatility of this process. The depth between 3 and 4 times the hole diameter is convenient for milling, ensuring both machining efficiency and accurate positioning.

[0044] In a further embodiment, the accuracy grades of the internal coolant drill bit and the internal coolant ball nose drill are H6 or above.

[0045] By using an internal coolant drill bit and an internal coolant ball nose drill with an accuracy grade of H6 or above, the clamping accuracy of the drill bit can be effectively guaranteed, and further, the machining efficiency and machining accuracy are ensured.

[0046] In a further embodiment, in S3, S4, S6, and S7, the water outlet pressure of the internal coolant drill bit and the internal coolant ball nose drill is between 10 bar and 50 bar.

[0047] During machining, the internal spray pressure is used to carry out the chips and heat generated during the cutting process, and it can also solve the problem of cooling during internal hole machining. The pressure should be between 10 bar and 50 bar. If it is too low, the chips and heat cannot be carried out, and if it is too high, the reaction force of the water flow during the cutting process of the tool will cause the tool to vibrate. By further limiting the water outlet pressure, the machining accuracy of the bottom and the hole wall of the deep hole can be further improved.

[0048] In a further embodiment, in S5 and S8, the pause time of the internal coolant drill bit and the internal coolant ball nose drill is between 0.2 and 0.4 seconds.

[0049] Pausing for 0.2 - 0.4 s at the bottom can prevent the problem that when the machine tool retracts, the rotational speed has not completely decreased and the high-pressure internal spray has not completely closed, resulting in an increase in tool swing, thus affecting the machining accuracy and tool life. Among them, pausing for 0.3 seconds can obtain better machining accuracy and machining efficiency.

[0050] In a further embodiment, in S6, when the internal coolant ball nose drill feeds to the depth position of L - [(D / 2) + 1] of the spot cooling hole, the internal coolant ball nose drill discharges water.

[0051] By setting the position of the internal coolant ball nose to start the high-pressure internal spray central water discharge at L - [(D / 2) + 1], it is possible to avoid the problem that the machining accuracy is reduced due to the tool tremor caused by the reaction force of the water flow while ensuring the machining efficiency, and further ensure the machining accuracy of the bottom and the hole wall of the deep hole and take into account the machining efficiency.

[0052] In a further embodiment, in S7, the jogging machining amount of the internal coolant ball nose drill for spot machining is 0.5 - 1% of the hole diameter D, and the jogging retraction amount is 2.5 - 3.5 times the jogging machining amount.

[0053] In actual machining, the rotational speed and feed can be adjusted with reference to the machining parameters provided by the tool supplier. Jogging machining can effectively solve the problem that there is no cutting edge at the bottom of the ball nose end mill and can machine the bottom of the hole with a ball nose end mill. The jogging machining amount should not be excessive. Generally, 1% of the hole diameter can balance machining efficiency and machining accuracy. The jogging retraction amount can be set to 2.5 - 3.5 times the actual jogging amount. Too much retraction wastes time and affects machining efficiency, while too little retraction cannot carry out the chips produced by cutting. When the jogging retraction amount is about 3 times the jogging machining amount, machining efficiency and machining accuracy can be balanced.

[0054] In a further embodiment, in S4, the machine tool drives the internal coolant drill to machine the point-cooling hole in a working state where the spindle speed is greater than S3 and the cutting feed is less than S3.

[0055] In S7, the machine tool drives the internal coolant ball nose end mill to machine the bottom of the point-cooling hole by point machining in a working state where the spindle speed is greater than S6 and the cutting feed is less than S7.

[0056] Embodiment

[0057] Case 1: Machining of a ball nose point-cooling hole with a depth of 180 mm and a hole diameter of 6 mm:

[0058] 1. Use a 4 mm milling cutter to machine a pilot hole with a depth of 20 mm and a diameter of 6 mm.

[0059] 2. Use a 6 mm carbide internal coolant drill with a precision grade of H6 to control the spindle speed at 200 r / min and the cutting linear speed at 200 m / min, and insert it into the pilot hole at a depth of 19 mm.

[0060] 3. Turn on the central coolant supply.

[0061] 4. Adjust the spindle speed to 1600 r / min and the cutting feed to 90 m / min, and machine to the position of 180 mm hole depth.

[0062] 5. Pause the cutting feed at the bottom of the hole for 0.3 seconds. After turning off the central coolant supply, adjust the spindle speed to 200 r / min and the cutting feed to 200 m / min, and then retract from the hole to the part safety plane.

[0063] 6. Use a 6 mm carbide internal coolant ball nose end mill with a precision grade of H6 to control the spindle speed at 200 r / min and the cutting linear speed at 200 m / min, insert it to the position of 176 mm, and turn on the central coolant supply.

[0064] 7. Adjust the spindle speed to 3600 r / min and the cutting feed to 90 m / min for jogging machining. The jogging amount is 0.06 mm and the retraction amount is 0.2 mm, and machine to the position of 180 mm at the bottom of the hole.

[0065] 8. Pause the cutting feed for 0.3 seconds. After closing the central coolant supply, adjust the spindle speed to 200 r / min and the cutting feed to 200 m / min, then retract from the hole to the part safety plane.

[0066] 9. Finish the machining.

[0067] Case 2: Machining of a ball-end spot-cooling hole with a depth of 260 mm and a hole diameter of 10 mm:

[0068] 1. Use a 6-mm milling cutter to machine a pilot hole with a depth of 30 mm and a diameter of 10 mm.

[0069] 2. Use a 10-mm carbide internal-coolant drill bit with an H6 precision grade, control the spindle speed at 200 r / min, and the cutting linear speed at 200 m / min, and insert it into the pilot hole to a depth of 29 mm.

[0070] 3. Turn on the central coolant supply.

[0071] 4. Adjust the spindle speed to 3000 r / min and the cutting feed to 89 m / min, and machine to the position of 260 mm hole depth.

[0072] 5. Pause the cutting feed at the bottom of the hole for 0.3 seconds. After closing the central coolant supply, adjust the spindle speed to 200 r / min and the cutting feed to 200 m / min, then retract from the hole to the part safety plane.

[0073] 6. Use a 10-mm carbide internal-coolant ball-end drill bit with an H6 precision grade, control the spindle speed at 200 r / min, and the cutting linear speed at 200 m / min, insert it to the position of 254 mm, and turn on the central coolant supply.

[0074] 7. Adjust the spindle speed to 3000 r / min and the cutting feed to 89 m / min for jogging machining, with a jog amount of 0.1 mm and a retraction amount of 0.3 mm, and machine to the bottom of the hole at 260 mm position.

[0075] 8. Pause the cutting feed for 0.3 seconds. After closing the central coolant supply, adjust the spindle speed to 200 r / min and the cutting feed to 200 m / min, then retract from the hole to the part safety plane.

[0076] 9. Finish the machining.

[0077] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation on the present invention itself. Various changes may be made in its form and details without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A processing technology for the ball head point cold holes of a die-casting module, characterized in that Including: S1. Determine the hole depth L and hole diameter D of the direct cooling holes of the die-casting module; S2. The machine tool processes a pilot hole on the die-casting module according to the hole diameter; S3. The machine tool feeds the internal cooling drill bit into the pilot hole and makes the internal cooling drill bit discharge water when the internal cooling drill bit reaches a predetermined position in the pilot hole; S4. The machine tool drives the internal cooling drill bit to process a direct cooling hole with a hole depth of L; S5. When the internal cooling drill bit processes a direct cooling hole with a hole depth of L, pause the internal cooling drill bit for a predetermined time, and then retract the internal cooling drill bit to the safety plane; S6. When the machine tool feeds the internal cooling ball head drill to a predetermined position of the direct cooling hole with a hole depth of L, make the internal cooling ball head drill discharge water; S7. The machine tool drives the internal cooling ball head drill to process the bottom of the direct cooling hole by point machining; S8. Pause the internal cooling ball head drill for a predetermined time, and then retract the internal cooling ball head drill to the safety plane.

2. The ball head direct cooling hole processing process of a die-casting module according to claim 1, characterized in that In S2, the machine tool uses a milling cutter to mill and process a pilot hole, and the depth of the pilot hole is 3 to 4 times the hole diameter D.

3. The ball head direct cooling hole processing process of a die-casting module according to claim 1, characterized in that In S3, S4 and S5, the accuracy grade of the internal cooling drill bit is H6 or above; In S6, S7 and S8, the accuracy grade of the internal cooling ball head drill is H6 or above.

4. The ball head direct cooling hole processing process of a die-casting module according to claim 1, characterized in that In S3 and S4, the water discharge pressure of the internal cooling drill bit is between 10 bar and 50 bar; In S6 and S7, the water discharge pressure of the internal cooling ball head drill is between 10 bar and 50 bar.

5. The ball head direct cooling hole processing process of a die-casting module according to claim 1, characterized in that In S5, the pause time of the internal cooling drill bit is between 0.2 and 0.4 seconds; In S8, the pause time of the internal cooling ball head drill is between 0.2 and 0.4 seconds.

6. The ball head direct cooling hole processing process of a die-casting module according to claim 1, characterized in that In S6, when the internal cooling ball head drill feeds to the depth position of L - [(D / 2) + 1] of the direct cooling hole, the internal cooling ball head drill discharges water.

7. The ball head direct cooling hole processing process of a die-casting module according to claim 1, characterized in that In S7, the jogging machining amount of the internal cooling ball head drill for point machining is 0.5% to 1% of the hole diameter D, and the jogging retraction amount is 2.5 to 3.5 times the jogging machining amount.

8. The ball head direct cooling hole processing process of a die-casting module according to claim 1, characterized in that In S4, the machine tool drives the internal cooling drill bit to process a direct cooling hole in a working state where the spindle speed is greater than the spindle speed in S3 and the cutting feed speed is less than the cutting feed speed in S3; In S7, the machine tool drives the internal cooling ball head drill to process the bottom of the direct cooling hole by point machining in a working state where the spindle speed is greater than the spindle speed in S6 and the cutting feed speed is less than the cutting feed speed in S6.

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