A processing method for a balance shaft bracket

Abstract

The present invention discloses a processing method for a balance shaft bracket, which is used to ensure the dimensional accuracy of key holes and the method for ensuring internal hole burrs. A large-diameter reamer is used to ensure the processing stability of deeper hole diameters, and then a drilling-boring-tapping process method is adopted to ensure the requirements of the symmetry and perpendicularity of threaded holes. A reasonable internal hole back-boring tool is used to effectively remove the burrs inside the intersecting holes, thereby effectively ensuring the processing quality and process stability of the balance shaft bracket.

Description

Technical Field

[0001] The present invention relates to the field of mechanical processing of automobile chassis parts, and in particular to a processing method of a balance shaft bracket. Background Art

[0002] The balance shaft bracket is a key component of the balanced suspension of the commercial vehicle chassis system. This balance shaft bracket is intended for export and has strict component requirements, high dimensional accuracy, a quality target of 30ppm, and a "zero" defect rate. The user only conducts random inspections on the parts. If any defect occurs, the batch of parts will be returned and 100% inventory inspection will be required to eliminate the defect. If such a situation occurs, it will have a huge impact on the company's image and economic benefits.

[0003] According to the quality requirements of this part, the process capability requirements for part processing are very high. We analyzed the balance shaft bracket and found the key items and processing difficulties that affect its processing:

[0004] First: The verticality and symmetry of the Φ105mm bearing hole and the M24mm threaded hole perpendicular to it are difficult to process in batch production;

[0005] Second, burr removal at the intersection of the Φ105mm bearing hole and the M24mm threaded inner hole is a difficult point and a key item for this part. Burrs in intersecting holes are usually difficult to remove, and are generally removed manually using files or pneumatic and electric milling heads or grinding heads. This method of burr removal is very likely to damage the inner hole or incompletely remove the burrs. For this product, the bearing hole is precision-machined, and if there are scratches or grinding marks in the hole, the part will be scrapped, resulting in great waste. How to effectively remove burrs in intersecting holes is also a key issue that needs to be solved by the patent of this invention.

[0006] Third: In the bearing hole of Φ105(+0.012, +0.047)mm*166.5mm, the surface roughness is Ra1.6μm. Because the hole is deep, taper is very likely to occur during boring, and manual tool jump error will occur, which is prone to problems such as large or small aperture or even out-of-tolerance.

[0007] Therefore, it is very important to choose the right processing method and fixture; how to ensure that there is not a single defective product in one millionth of the pieces is the difficulty. Summary of the Invention

[0008] In response to the problems existing in the prior art, the present invention provides a processing method mainly for a balance shaft bracket. By adopting the processing scheme of this scheme, not only can the accuracy between the bearing hole and the threaded hole be well guaranteed; at the same time, the burrs at the junction of the two can be effectively removed, which greatly promotes the quality of the finished product of the entire balance shaft bracket.

[0009] Specifically, the detailed technical solution proposed by the present invention is as follows:

[0010] A processing method for a balance shaft bracket specifically includes the following steps:

[0011] S1. Install and fix the balance shaft bracket on the positioning fixture;

[0012] S2. Process the balance shaft bracket in a horizontal machining center. Specifically, a bearing hole is machined in the exact center of the balance shaft bracket;

[0013] S3. Continue to process the balance shaft bracket in the horizontal machining center. Specifically, a threaded hole is machined on the balance shaft bracket, and the threaded hole penetrates to the bearing hole, and the perpendicularity and symmetry of the threaded hole relative to the bearing hole are ensured;

[0014] S4. Fix the internal chamfering tool to the spindle of the horizontal machining center. The cutting head of the internal chamfering tool is configured to gradually retract when subjected to an external force and automatically rebound when the external force disappears; insert the cutting head along the threaded hole into the bearing hole, start the spindle to rotate and move, so that the cutting head chamfers at the intersection of the bearing hole and the threaded hole;

[0015] S5. After chamfering is completed, the spindle stops rotating and the cutting head is facing down at this time; then the spindle retracts and gradually withdraws the tool until the tool completely exits.

[0016] Furthermore, in step S1, the proposed positioning fixture includes a bottom plate, and a front-back direction positioning component, an up-down direction positioning component, and a lateral positioning component are provided on the bottom plate;

[0017] The front-back direction positioning component is configured to position and fix the balance shaft bracket in the front-back direction;

[0018] The up-down direction positioning component is configured to position and fix the balance shaft bracket in the up-down direction;

[0019] The lateral positioning component is configured to position and fix the balance shaft bracket in the left-right direction.

[0020] Furthermore, the front-back direction positioning component includes a positioning block and a rotary pressing head;

[0021] First supports are respectively and fixedly connected to the left and right sides of the bottom plate. A positioning block is installed and fixed on the top of each first support; a rotary pressing head is also fixed on each first support, and the rotary pressing head corresponds to the positioning block one by one; after the balance shaft bracket abuts against the positioning block, then rotate the rotary pressing head to press against the balance shaft bracket.

[0022] Further, the front-back direction positioning assembly further includes a bottom punch. The positioning block and the rotary punch are configured to restrict the top of the balance shaft bracket, and the bottom punch is configured to restrict the bottom of the balance shaft bracket.

[0023] Further, the up-down direction positioning assembly includes a positioning pin;

[0024] Second supports are respectively fixedly connected to the left and right sides of the bottom plate, and the positioning pins are installed at the tops of each of the second supports; the positioning pins extend vertically upward.

[0025] Further, the lateral positioning assembly includes an adjusting pressure rod;

[0026] A third support is also fixedly connected to the bottom plate, and the adjusting pressure rod is movably connected to the upper end of the third support; the adjusting pressure rod is manually adjusted to position and fix the side of the balance shaft bracket.

[0027] Further, in step S2, the bearing hole is machined by rough boring, semi-finish boring, and reaming in sequence; specifically, rough boring is performed according to the specification of Φ103.5±0.1mm, semi-finish boring is performed according to the specification of Φ104.7±0.05mm, the tool used for semi-finish boring is a fine boring tool with fine adjustment, and a large-diameter reamer is used to ensure the reaming operation of the Φ105mm(+0.012, +0.047) hole diameter tolerance and roundness tolerance of 0.018mm;

[0028] The cutting parameters for reaming are: the spindle speed is 260rpm / min, and the feed speed is 200m / min.

[0029] Further, in step S3, the threaded hole is machined by drilling a bottom hole, finish boring the bottom hole, chamfering the hole opening, and tapping in sequence; specifically, the bottom hole is drilled as Φ20.6mm(+0.1, 0), then a Φ44mm hole is counterbored, then the threaded bottom hole is finish bored to Φ21mm(+0.15, 0), then a 15° chamfer is made at the orifice of the threaded bottom hole, and finally threading is performed.

[0030] Further, in step S4, the internal chamfering tool includes a tool shank and a tool head. The tool head is elastically built into the tool shank, and the tool head retracts into the tool shank when a force is applied; when the tool head is not stressed, the cutting edge in the tool head is outside the tool shank.

[0031] The beneficial effects achieved by adopting this technical solution are:

[0032] By adopting the processing method provided in this solution, the key technical difficulties in the processing of the balance shaft bracket are solved, and three difficult problems are comprehensively solved (firstly, the opening accuracy of the bearing hole; secondly, the perpendicularity and symmetry between the threaded hole and the bearing hole; thirdly, the cleaning problem of the burr at the intersection of the bearing hole and the threaded hole), thus effectively ensuring the processing stability of the parts and the stability of the mass production process; especially for the internal chamfer of the intersecting holes, the method is simple, the chamfer is reliable, and there is no burr in the hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. is a finished product structure diagram of the balance shaft bracket, showing the hole parts to be processed.

[0034] Figure 2 For Figure 1 the bearing hole and the threaded hole indicated by the arrow in

[0035] Figure 3 FIG. is the front view of fixing the balance shaft bracket on the positioning fixture.

[0036] Figure 4 FIG. is the right view of fixing the balance shaft bracket on the positioning fixture.

[0037] Figure 5 FIG. is the left view of fixing the balance shaft bracket on the positioning fixture.

[0038] Figure 6 FIG. is the top view of fixing the balance shaft bracket on the positioning fixture.

[0039] Figure 7 FIG. is the process flow chart of machining the threaded hole.

[0040] Figure 8 FIG. is the schematic diagram of removing burrs using an internal chamfering tool. DETAILED DESCRIPTION OF THE INVENTION

[0041] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0042] In this embodiment, a processing method for a balance shaft bracket is provided. By adopting the processing method provided in this solution, the holes ( Figure 1 in the finished product drawing of the balance shaft bracket) in the balance shaft bracket ( Figure 2 the bearing hole 101 and the threaded hole 102 in

[0043] are machined to ensure the quality stability of the balance shaft bracket 100 and minimize the occurrence of defective products.

[0044] Step 1: Install and fix the balance shaft bracket on the positioning fixture; at this time, the balance shaft bracket 100 already has a preliminary shape, so here mainly explains how to complete the machining of the bearing hole 101 and the threaded hole 102.

[0045] In this step, referring to Figure 3 - Figure 6 , the proposed positioning fixture includes a bottom plate 11. The bottom plate 11 serves as the main supporting structure, providing a stable foundation guarantee for the layout and support of the entire fixture structure; on the bottom plate 11, there are front-back direction positioning components, up-down direction positioning components, and lateral positioning components; among them, the front-back direction positioning components are configured to position and fix the balance shaft bracket 100 in the front-back direction; the up-down direction positioning components are configured to position and fix the balance shaft bracket 100 in the up-down direction; the lateral positioning components are configured to position and fix the balance shaft bracket 100 in the left-right direction.

[0046] Through the mutual cooperation between the three positioning components, it is ensured that the balance shaft bracket is stably positioned and fixed in the positioning fixture here.

[0047] In this embodiment, the front-back direction positioning components include positioning blocks 21 and rotary pressing heads 22; and, on the left and right sides of the bottom plate 11, first supports 12 are respectively fixedly connected. At the top of each first support 12, a positioning block 21 is installed and fixed; a rotary pressing head 22 is also fixed on each first support 12, and here the rotary pressing heads 22 correspond one-to-one with the positioning blocks 21; after the balance shaft bracket abuts against the positioning blocks 21, the rotary pressing heads 22 are rotated to press against the balance shaft bracket to ensure stability.

[0048] In this embodiment, the front-back direction positioning components further include bottom pressing heads 23. The positioning blocks 21 and rotary pressing heads 22 are configured to restrict the top of the balance shaft bracket, and the bottom pressing heads 23 are configured to restrict the bottom of the balance shaft bracket.

[0049] In this embodiment, the up-down direction positioning components include positioning pins 31; on the left and right sides of the bottom plate 11, second supports 13 are respectively fixedly connected. At the top of each second support 13, the positioning pins 31 are installed; and the positioning pins 31 extend vertically upward for plugging and aligning with the pin holes in the balance shaft bracket.

[0050] In this embodiment, the lateral positioning components include adjusting pressure rods 41; on the bottom plate 11, a third support 14 is also fixedly connected. The adjusting pressure rods 41 are movably connected to the upper ends of the third supports 14; manually adjust the adjusting pressure rods 41 to position and fix the sides of the balance shaft bracket 100.

[0051] The specific positioning method is as follows:

[0052] After placing the balance shaft bracket into the positioning tooling here, first rotate the adjusting pressure bar 41 to tighten the balance shaft bracket to the left. This is a pre-tightening process that can be done with the strength of your hand. Then, use a wrench to pre-tighten the rotating pressure head 22, and use a socket wrench to rotate and pre-tighten the bottom pressure head 23. Finally, gradually rotate the rotating pressure head 22 and the bottom pressure head 23 to fully tighten them, and the balance shaft bracket is clamped on the tooling.

[0053] Step 2: Machine the balance shaft bracket on a horizontal machining center. Specifically, machine the bearing hole 101 in the exact center of the balance shaft bracket.

[0054] In this step, when machining the bearing hole 101 with a diameter of Φ105(+0.012, +0.047)mm and a depth of 166.5mm, the roundness requirement of the hole is 0.018mm. The method used is rough boring - semi-finish boring - finish boring. This hole is machined on a horizontal machining center. To better ensure the consistency of the batch-processed hole diameters, the present invention adopts a new machining method, that is, the bearing hole is machined in the order of rough boring, semi-finish boring, and reaming. Specifically, rough boring is carried out according to the specification of Φ103.5±0.1mm, semi-finish boring is carried out according to the specification of Φ104.7±0.05mm, the tool used for semi-finish boring is a fine boring tool with fine adjustment, and finally a large-diameter reamer is used to ensure the reaming operation of the Φ105mm(+0.012, +0.047) hole diameter tolerance and the roundness tolerance of 0.018mm.

[0055] It should be noted that the cutting parameters for reaming here are: the spindle speed is 260rpm / min, and the feed rate is 200m / min.

[0056] Step 3: Continue to machine the balance shaft bracket on the horizontal machining center. Specifically, machine the threaded hole 102 on the balance shaft bracket 100. The threaded hole 102 penetrates to the bearing hole 101, and the perpendicularity and symmetry of the threaded hole 102 relative to the bearing hole are ensured.

[0057] In this step, the commonly used processing route is drilling - tapping. For the processing quality requirements of this product, if the usual processing method is used, it cannot well ensure the perpendicularity of 0.05mm of the threaded hole and the symmetry of 0.05mm relative to the bearing hole. In view of the defect that the symmetry and perpendicularity cannot effectively ensure the machining accuracy by the usual processing method, the present invention adopts a new processing guarantee method, that is, the threaded hole is machined in the order of drilling the bottom hole, finish boring the bottom hole, chamfering the hole opening, and tapping. Specifically, see Figure 7, drill a bottom hole with a diameter of Φ20.6mm (+0.1, 0), then countersink a Φ44mm hole, then finish boring the thread bottom hole with a diameter of Φ21mm (+0.15, 0), then chamfer the orifice of the thread bottom hole at 15°, and finally tap the thread to ensure the thread hole M24*3.

[0058] Step 4: Fix the internal chamfering tool 50 to the spindle of the horizontal machining center. The tool head of the internal chamfering tool is configured to gradually retract when subjected to an external force and automatically rebound when the external force disappears; insert the tool head along the thread hole into the bearing hole, start the spindle to rotate and move, so that the tool head chamfers at the intersection of the bearing hole and the thread hole.

[0059] In this step, refer to Figure 8 , the provided internal chamfering tool includes a tool shank 51 and a tool head 52. The tool head 52 is elastically built into the tool shank 51 and retracts into the tool shank 51 when the tool head 52 is stressed; when the tool head 52 is not stressed, the cutting edge in the tool head is outside the tool shank 51.

[0060] Specifically, during machining, insert the tool shank 51 along the M24 thread hole into the bottom hole gradually until it reaches the intersection with the bearing hole 101. After the tool enters the hole, the tool head 52 will automatically spring up because there is no restriction from the thread hole wall; then start the spindle to rotate and slowly retract, so that the tool chamfers in the intersecting hole until the chamfering is completed.

[0061] Step 5: After the chamfering is completed, the spindle stops rotating and the tool head is facing down at this time; then the spindle retracts and gradually withdraws the tool until the tool is completely withdrawn. That is, after the chamfering is completed, the machine tool spindle stops rotating, and then the tool is withdrawn. When withdrawing the tool, the tool head is facing down and the tool is withdrawn.

[0062] By adopting the processing method provided by this solution, the key technical difficulties in the processing of the balance shaft bracket are solved, and three difficult problems are solved overall (one is the opening accuracy problem of the bearing hole; the second is the perpendicularity and symmetry problems between the thread hole and the bearing hole; the third is the cleaning problem of burrs at the intersection of the bearing hole and the thread hole), which effectively ensures the processing stability of the parts and the stability of the batch production process.

[0063] Especially for the internal chamfering of intersecting holes, the method is simple, the chamfering is reliable, and there are no burrs in the hole. In the past, for the internal chamfering of similar intersecting holes, manual tools such as manual chamfering tools or pneumatic grinders with grinding heads were used for grinding, resulting in poor grinding quality and appearance, and even damage to the quality of the already machined inner hole wall; the internal chamfering tool 50 provided by the present invention has a telescopic tool head 52, and the method of performing reverse chamfering in the intersecting hole (the intersection of the bearing hole and the thread hole) is simple, the chamfering is stable, has good consistency, is of reliable quality, has no burrs in the hole, and avoids damage to the already machined hole wall.

[0064] It should be noted that like reference numerals and letters refer to like items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0065] It should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship in which the technical product is usually placed during use. It is only for the convenience of describing the present technology and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present technology. In addition, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Therefore, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0066] In addition, terms such as "horizontal", "vertical", "hanging", etc. do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0067] In the description of the present technology, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present technology can be understood according to specific situations.

[0068] The above are only the preferred embodiments of the present technology. It should be pointed out that due to the limited nature of literal expression and objectively existing infinite specific structures, for those of ordinary skill in the art of the present technology, without departing from the principle of the present technology, several improvements, modifications or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, modifications, changes or combinations, or directly applying the concept and technical solution of the technology to other occasions without improvement, should all be regarded as the protection scope of the present technology.

Claims

1. A processing method for a balance shaft bracket, characterized in that, Specifically, it includes the following steps: S1. Install and fix the balance shaft bracket on the positioning fixture; S2. Machine the balance shaft bracket in a horizontal machining center. Specifically, machine a bearing hole in the exact center of the balance shaft bracket; S3. Continue to machine the balance shaft bracket in the horizontal machining center. Specifically, machine threaded holes on the balance shaft bracket, and the threaded holes penetrate to the bearing hole, and ensure the perpendicularity and symmetry of the threaded holes relative to the bearing hole; S4. Fix the internal chamfering tool to the spindle of the horizontal machining center. The cutting head of the internal chamfering tool is configured to gradually retract when subjected to an external force and automatically rebound when the external force disappears; Insert the cutting head along the threaded hole into the bearing hole, start the spindle to rotate and move, so that the cutting head chamfers at the intersection of the bearing hole and the threaded hole; S5. After chamfering is completed, the spindle stops rotating and the cutting head is downward at this time; Then the spindle retracts and gradually withdraws the tool until the tool completely exits; In step S1, the positioning fixture includes a bottom plate, and a front-back direction positioning component, an up-down direction positioning component, and a side direction positioning component are provided on the bottom plate; The front-back direction positioning component is configured to position and fix the balance shaft bracket in the front-back direction; The up-down direction positioning component is configured to position and fix the balance shaft bracket in the up-down direction; The side direction positioning component is configured to position and fix the balance shaft bracket in the left-right direction; The front-back direction positioning component includes a positioning block and a rotating press head; First supports are respectively fixedly connected to the left and right sides of the bottom plate. A positioning block is installed and fixed on the top of each first support; A rotating press head is also fixed on each first support, and the rotating press head corresponds to the positioning block one by one; After the balance shaft bracket abuts against the positioning block, rotate the rotating press head to press against the balance shaft bracket; The front-back direction positioning component further includes a bottom press head. The positioning block and the rotating press head are configured to limit the top of the balance shaft bracket, and the bottom press head is configured to limit the bottom of the balance shaft bracket; The up-down direction positioning component includes a positioning pin; Second supports are respectively fixedly connected to the left and right sides of the bottom plate. The positioning pin is installed on the top of each second support; The positioning pin extends vertically upward; The side direction positioning component includes an adjusting pressure rod; A third support is also fixedly connected to the bottom plate, and the adjusting pressure rod is movably connected to the upper end of the third support; Manually adjust the adjusting pressure rod to position and fix the side of the balance shaft bracket.

2. The processing method of a balance shaft bracket according to claim 1, characterized in that, In step S2, the machining of the bearing hole is completed by successively using rough boring, semi-finish boring, and reaming: Specifically, rough boring is carried out according to the specification of Φ103.5±0.1mm, semi-finish boring is carried out according to the specification of Φ104.7±0.05mm, and the tool used for semi-finish boring is a fine boring tool with fine adjustment. A large-diameter reamer is used to ensure the reaming operation of the Φ105mm (+0.012, +0.047) hole diameter tolerance and roundness tolerance of 0.018mm; The cutting parameters for reaming are: the spindle speed is 260 rpm / min, and the feed speed is 200 m / min.

3. The processing method of a balance shaft bracket according to claim 1, characterized in that: In step S3, the machining of the threaded hole is completed by successively drilling a bottom hole, finely boring the bottom hole, machining a chamfer at the hole opening, and tapping: specifically, the bottom hole is drilled to Φ20.6mm (+0.1, 0), then a Φ44mm hole is counterbored, then the threaded bottom hole is finely bored to Φ21mm (+0.15, 0), then a 15° chamfer is made at the orifice of the threaded bottom hole, and finally the thread is tapped.

4. The processing method of a balance shaft bracket according to claim 1, characterized in that, In step S4, the internal chamfering tool includes a tool shank and a tool head. The tool head is elastically built into the tool shank and retracts into the tool shank when the tool head is stressed; when the tool head is not stressed, the cutting edge in the tool head is outside the tool shank.

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