A special fixture and processing method for numerical control processing of a space structure of a knotter support

Abstract

The application provides a special fixture and processing method for numerical control processing of a knotter support space structure, comprising a three-axis machine tool fixture and a four-axis machine tool fixture; first, a to-be-processed knotter support is clamped on the three-axis machine tool fixture and the lower end face of the main shaft hole and the end face thereof are processed, and then an absolute coordinate system is established based on the same; and then, according to the absolute coordinate system of the main shaft hole and the end face thereof, the shaft hole of the knife arm, the shaft hole of the rope clamping disc, the shaft hole of the knotting nozzle, the cylindrical cam surface at the knotting nozzle, and the shaft hole of the worm shaft are processed on the four-axis numerical control machine tool; and during the processing, the absolute coordinate system of the four-axis numerical control machine tool is changed into the coordinate system of the to-be-processed shaft hole, and the processing is completed. The three-axis machine tool and the four-axis numerical control machine tool are used to replace the five-axis machine tool, so that the processing cost can be greatly reduced, the economic benefit is improved, and the processing precision requirement of the knotter support is met.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of mechanical processing, and particularly relates to a special fixture for numerical control processing of a space structure of a knotter support and a processing method. BACKGROUND

[0002] A square bale baler is an important equipment for processing straw after crop harvesting, and a knotter is a core component of the square bale baler. The knotter support, as a main structure of the knotter, is a very complex special-shaped workpiece, and each shaft hole has a strict spatial positional relationship, and the assembly precision requirement is high. In addition, the shaft hole and the surface are difficult to process and are not easy to process. If the processing is not accurate, the support blank will be easily wasted.

[0003] The existing Chinese patent 201910017957.X designs a five-axis numerical control machining method and fixture for a double-toothed disc driven knotter support: the knotter support can be machined by clamping once, and the second positioning block with the main shaft hole auxiliary positioning is adopted to realize accurate tool setting, solve the offset of the main shaft hole axis due to the casting error of the support blank, and effectively improve the processing efficiency of the support.

[0004] However, the processing cost of the five-axis numerical control machine tool is high, and the popularization rate is not as high as that of the four-axis numerical control machine tool. Under the requirement of ensuring the processing precision of the support, when producing a large number of knotter supports, the five-axis numerical control machine tool cannot balance the contradiction between the quantity and cost of support processing. Replacing the five-axis machine tool with a four-axis numerical control machine tool can greatly reduce the processing cost and improve the economic benefit. SUMMARY

[0005] In view of the above technical problems, one of the purposes of one mode of the present application is to provide a special fixture for numerical control processing of a space structure of a knotter support, which includes a three-axis machine tool fixture and a four-axis machine tool fixture. The three-axis machine tool fixture can clamp the knotter support to be processed, and process the lower end face counterbore and the end face of the main shaft hole on the three-axis machine tool. The four-axis machine tool fixture can clamp the knotter support to be processed processed by the three-axis machine tool, and process the tool arm shaft hole, the rope clamping disc shaft hole, the knotter nozzle shaft hole, the cylindrical cam surface at the knotter nozzle, and the worm shaft shaft hole. Through the cooperation of the three-axis machine tool fixture and the four-axis machine tool fixture, the knotter support processing precision requirement can be met, the five-axis machine tool is replaced to process the knotter support, the processing cost is reduced, and the economic benefit is improved.

[0006] One of the purposes of one embodiment of the present application is to provide a numerical control machining method for a knotter support space structure, comprising the following steps: first clamping the knotter support on a three-axis machine tool clamp, machining the main shaft hole of the knotter support as a reference hole, establishing an absolute coordinate system, then clamping the knotter support on a four-axis machine tool clamp, finding the coordinates of the corresponding machining position according to the absolute coordinate system established by the three-axis machine tool, transforming the coordinate system to move the position to be machined to the machining station, and completing the machining of the remaining positions. By first machining on a three-axis machine tool to establish an absolute coordinate system, and then transforming the coordinate system of the shaft hole on a four-axis machine tool, the machining precision requirements of the knotter support can be met, and the knotter support can be machined instead of a five-axis machine tool, thereby reducing the machining cost and improving the economic benefit.

[0007] Note that the recitation of these objects does not preclude the existence of other objects. One embodiment of the present application does not need to achieve all the above-mentioned purposes. The purposes other than the above-mentioned purposes can be extracted from the recitations of the specification, drawings and claims.

[0008] The present application achieves the above technical purposes through the following technical means.

[0009] A numerical control machining special fixture for a knotter support space structure, comprising a three-axis machine tool clamp and a four-axis machine tool clamp;

[0010] The three-axis machine tool clamp is used to be installed on a three-axis machine tool, and to fully constrain the knotter support when machining the lower end face counterbore and the end face of the main shaft hole of the knotter support.

[0011] The four-axis machine tool clamp is used to be installed on a four-axis machine tool, and to fully constrain the knotter support when machining the cutter arm shaft hole, the rope clamping disc shaft hole, the knotting nozzle shaft hole, the cylindrical cam surface at the knotting nozzle, the worm shaft shaft hole, and the upper end counterbore and the end face of the main shaft hole.

[0012] In the above scheme, the three-axis machine tool clamp comprises a three-axis clamp mounting plate, a three-axis clamp positioning spindle, a three-axis clamp pressing block, a three-axis clamp pressing plate support shaft, and a three-axis clamp positioning block.

[0013] The three-axis clamp positioning spindle is arranged on the three-axis clamp mounting plate and is used to cooperate with the unprocessed main shaft hole of the knotter support for positioning, and the three-axis clamp positioning spindle is a stepped shaft; the three-axis clamp pressing plate is arranged on the support shaft three-axis clamp mounting plate; the three-axis clamp pressing block is arranged at the top of the three-axis clamp mounting plate at both ends and is used to constrain the top of the knotter support; the three-axis clamp positioning block is arranged on the three-axis clamp mounting plate, and the three-axis clamp positioning block is a wedge-shaped block, and the wedge surface of the three-axis clamp positioning block is in contact with the inclined surface of the worm shaft hole of the knotter support.

[0014] In the scheme, the four-axis machine tool clamp comprises a four-axis clamp mounting plate, a fixed base plate, a cylindrical support, a rotary bearing, a fixed positioning base, a rotary positioning base, a positioning pin shaft, a support positioning block, a support wedge-shaped pressing plate, a support cylindrical pressing plate, a main shaft hole anti-deflection positioning block, a positioning stepped shaft and a main shaft hole concentric positioning block.

[0015] The four-axis clamp mounting plate is arranged at the bottom of the fixed base plate; the fixed positioning base is arranged on the fixed base plate; the rotary bearing is arranged on the fixed positioning base; the rotary positioning base is arranged on the rotary bearing; the fixed positioning base and the rotary positioning base are provided with through holes, and the positioning pin shaft is used for positioning the rotary positioning base through the through holes; the cylindrical support is arranged between the fixed base plate and the rotary positioning base, and is used for supporting the rotary positioning base; the support positioning block, the main shaft hole anti-deflection positioning block and the positioning stepped shaft are arranged on the rotary positioning base; the support positioning block and the main shaft hole anti-deflection positioning block are matched to limit the deflection of the knotter support bracket in the circumferential direction of the main shaft hole and the radial displacement; the main shaft hole anti-deflection positioning block is provided with a protrusion, the protrusion is provided with a bolt, and the bolt is matched with the positioning stepped shaft; the positioning stepped shaft is used for cooperating with the main shaft hole of the knotter support bracket for positioning; the main shaft hole concentric positioning block is arranged at the top of the positioning stepped shaft, and is used for positioning the axis of the main shaft hole of the knotter support bracket and restraining the direction of the main shaft hole axis of the knotter support bracket; the support wedge-shaped pressing plate is arranged on the rotary positioning base, and is used for restraining the cavity above the bottom of the knotter support bracket; the support cylindrical pressing plate is arranged on the rotary positioning base, and is used for restraining the concave surface of the main shaft hole and the cutter arm shaft hole of the knotter support bracket.

[0016] In the scheme, the first stepped shaft of the three-axis clamp positioning spindle has a cylindricality less than 0.01 mm, and the coaxiality between the first stepped shaft and the unprocessed main shaft of the knotter support bracket is less than 0.025 mm; the parallelism between the second stepped shaft end face and the mounting plate is less than 0.04 mm.

[0017] A numerical control machining method of a knotter support bracket space structure comprises the following steps:

[0018] First, the knotter support bracket is clamped by a three-axis machine tool clamp, the main shaft hole of the knotter support bracket is machined as a reference hole, and an absolute coordinate system is established; then, the knotter support bracket is clamped by a four-axis machine tool clamp, the coordinates of the corresponding machining positions are found according to the absolute coordinate system established by the three-axis machine tool, the coordinate system is transformed, and the machining positions are moved to the machining stations, and the machining of the cutter arm shaft hole, the rope clamping disc shaft hole, the knotting nozzle shaft hole, the cylindrical cam surface at the knotting nozzle, the worm shaft hole and the upper end hole of the main shaft hole and the end face thereof is completed.

[0019] The rest of the shaft hole and cylindrical cam surface are processed, and the rotation of the rotary bearing is used to compensate for the B-axis freedom of the four-axis numerical control machine tool in the four-axis machine tool fixture assembly. In the four-axis numerical control machining, the horizontal plane L is established by translating the bottom surface of the knotter support a certain distance upward, and the origin O is established by the intersection of the horizontal plane L and the spindle hole axis of the knotter support. During the shaft hole processing, the workpiece is first rotated by a certain angle around the A-axis of the four-axis machine tool, then the workpiece is rotated by a certain angle around the B-axis of the fixture, and then the positioning pin shaft is used for positioning, so that the end face of the shaft hole to be processed is perpendicular to the tool shaft Z-axis. The tool is moved to the center coordinate of the shaft hole to be processed, and the machining of each shaft hole is completed by feeding up and down along the Z-axis.

[0020] The above scheme comprises the following steps:

[0021] Step S1: three-axis machine tool clamping: clamping the three-axis machine tool fixture on the three-axis numerical control machine tool, and clamping the unprocessed knotter support on the three-axis machine tool fixture;

[0022] Step S2: three-axis machine tool tool setting: positioning the element with the outer contour of the knotter support spindle after clamping in step S1 as the axis, measuring the axis position of the knotter support spindle hole, setting it as the reference axis, establishing the absolute coordinate system and the absolute coordinate origin with the lower end surface of the knotter support spindle hole as the reference plane and making the reference axis perpendicular to the reference plane; completing the tool setting according to the absolute coordinate system and the absolute coordinate origin;

[0023] Step S3: three-axis machine tool processing: using the three-axis machine tool tool to complete the processing of the lower end surface counterbore and the end surface of the knotter support spindle after clamping in step S1;

[0024] Step S4: four-axis machine tool clamping: clamping the four-axis machine tool fixture on the four-axis numerical control machine tool, and clamping the knotter support processed in step S3 on the four-axis machine tool fixture;

[0025] Step S5: four-axis machine tool tool setting: taking the lower end surface of the knotter support spindle hole processed in step S3 as the reference surface, taking the concentric positioning block of the spindle hole as the axis positioning element, determining the spindle hole axis as the reference axis, establishing the four-axis numerical control machine tool coordinate system with the intersection of the reference surface and the reference axis as the workpiece coordinate origin, setting the tool, and determining the positions of the shaft hole, the knotting nozzle shaft hole, the worm shaft hole, and the rope clamping disc shaft hole in the absolute coordinate system according to the absolute coordinate system of the four-axis numerical control machine tool;

[0026] Step S6: Four-axis machine tool processing: sequentially processing the knife arm shaft hole, the rope clamping disc shaft hole, the knot nozzle shaft hole, the cylindrical cam surface at the knot nozzle, the worm shaft hole, when processing the above positions, rotating the four-axis numerical control machine tool processing platform according to the shaft hole position to be processed, changing from the four-axis numerical control machine tool absolute coordinate system to the coordinate system of the shaft hole to be processed; making the shaft hole or the curved surface to be processed reach the processing station, and then processing; the coordinate system of the cylindrical cam surface at the knot nozzle is the same as that of the knot nozzle shaft hole; after the above processing is completed, the main shaft hole concentric positioning block is removed, and the processing of the main shaft hole upper end counterbore and the end face thereof is completed.

[0027] In the above scheme, the change from the four-axis numerical control machine tool absolute coordinate system to the coordinate system of the shaft hole to be processed needs to be rotated around the A-axis and the B-axis respectively, the A-axis is the Y-axis of the four-axis numerical control machine tool, and the B-axis is the Z-axis of the four-axis numerical control machine tool, and the coordinate transformation matrix is:

[0028] T=T A T Β

[0029] In the formula, T A is the transformation matrix of rotation around the A-axis, T Β is the transformation matrix of rotation around the B-axis, and i is the processing sequence.

[0030]

[0031]

[0032] Wherein, θ is the angle of rotation around the A-axis, and β is the angle of rotation around the B-axis.

[0033] Further, the position D i of the center of the shaft hole to be processed in the four-axis numerical control machine tool absolute coordinate system after the coordinate system transformation of step S6 is:

[0034]

[0035] Wherein, x i ', y i ', z i ' are the positions of the center of the shaft hole to be processed in the four-axis numerical control machine tool absolute coordinate system after transformation, and x i , y i , z i are the positions of the center of the shaft hole to be processed in the four-axis numerical control machine tool absolute coordinate system before transformation.

[0036] In the above scheme, the clamping and positioning process of machine tool processing adopts an edge finder, and the main shaft line corresponding to the outer contour of the support shaft hole is determined in a four-point positioning manner.

[0037] Further, when the main axis corresponding to the outer contour of the support shaft hole is determined, the machining coordinates of each shaft hole of the support are adjusted to compensate for the casting error of the knotter support; the error value between the reference point of the unprocessed knotter support and the theoretical reference point is measured by the edge finder as Δx i Δy i Δz i Then the average value of the error values in each direction is obtained; the average value of the deviation of the initial coordinate system origin of the blank and the ideal coordinate system origin in each direction is recorded as (Δx, Δy, Δz), and the corrected machining coordinates can be calculated:

[0038]

[0039] Then the corrected machining absolute coordinates of each shaft hole of the knotter support are (x i ′+Δx′ y i ′+Δy′ z i ′+Δz′).

[0040] Compared with the prior art, the beneficial effects of the present application are:

[0041] According to one mode of the present application, the three-axis machine tool clamp can clamp the knotter support to be processed, the main shaft hole lower end face counterbore and the end face thereof are machined on the three-axis machine tool, the four-axis machine tool clamp can clamp the knotter support to be processed machined by the three-axis machine tool, and the knife arm shaft hole, the rope clamping disc shaft hole, the knotting nozzle shaft hole, the cylindrical cam surface at the knotting nozzle, and the worm shaft shaft hole are machined. Through the cooperation of the three-axis machine tool clamp and the four-axis machine tool clamp, the machining precision requirement of the knotter support can be met, the five-axis machine tool is replaced to machine the knotter support, the machining cost is reduced, and the economic benefit is improved.

[0042] According to one mode of the present application, by first machining on the three-axis machine tool to establish an absolute coordinate system, and then transforming the coordinate system of the shaft hole on the four-axis machine tool, the machining precision requirement of the knotter support can be met, the five-axis machine tool is replaced to machine the knotter support, the machining cost is reduced, and the economic benefit is improved.

[0043] According to one mode of the present application, the rotary positioning base can rotate around the axis of the rotary bearing, and this rotary motion increases the degree of freedom of the four-axis numerical control machining machine tool. After the rotary positioning base is rotated to a specified position, the rotary positioning base is connected with the fixed positioning base by using the positioning pin shaft. In this way, the machining of the main shaft hole and part of the surface of the knotter support with a complex spatial structure can be completed on the four-axis numerical control machine tool, the machining precision meets the requirement, and the machining cost is greatly reduced compared with the five-axis numerical control machining scheme.

[0044] According to one mode of the present application, the present application ensures good coaxiality between the upper end counterbore of the knotter support and the lower end counterbore thereof during machining of the upper end counterbore by bolt connection of the machined main shaft hole concentric positioning block with the stepped positioning shaft.

[0045] According to one mode of the present application, the knife arm shaft hole is a stepped hole, the inner hole is machined by drilling and reaming, and the counterbore is machined by boring; the rest, such as the rope disc shaft hole, the knotter nozzle shaft hole, and the worm shaft hole, are machined by the processing procedure of drilling first and reaming later. The above-mentioned machining process reduces the positioning reference conversion of the machine tool, improves the machining precision and machining efficiency.

[0046] According to one mode of the present application, there is a cylindrical support between the knotter support fixed base plate and the rotating base, which is connected with the fixed base plate when the rotating base is rotated to a specified position. After being connected, the cylindrical support can reduce the deformation of the rotating positioning base along the axis direction of the positioning stepped shaft when the tool is fed, and accordingly can reduce the stress of the rotary bearing, thereby prolonging the service life of the rotary bearing.

[0047] Note that the description of these effects does not preclude the presence of other effects. One mode of the present application does not necessarily have all the above-mentioned effects. Effects other than the above-mentioned can be clearly seen and extracted from the description, drawings, claims, etc. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 is a schematic view of a three-axis machine tool jig structure according to one embodiment of the present application.

[0049] Figure 2 is a three-view drawing of a three-axis machine tool jig according to one embodiment of the present application, wherein, Figure 2 (a) is a front view, Figure 2 (b) is a right view, Figure 2 (c) is a top view.

[0050] Figure 3 is a schematic view of a coordinate system of a knotter support in absolute coordinates of a machine tool after coordinate transformation according to one embodiment of the present application.

[0051] Figure 4 is a schematic view of a four-axis machine tool jig structure according to one embodiment of the present application.

[0052] Figure 5 is a front view of a four-axis machine tool jig according to one embodiment of the present application.

[0053] Figure 6 is a schematic view of the machining process of the knife arm shaft hole of the knotter support according to the present application, wherein Figure 6(a) is a front view after coordinate transformation, Figure 6(b) is a side view after position transformation, and Figure 6(c) is a top view after position transformation.

[0054] Fig. 7 is a schematic diagram of the processing procedure of the shaft hole of the knotter support rope disc shaft, wherein Fig. 7(a) is the front view after coordinate transformation, Fig. 7(b) is the side view after position transformation, and Fig. 7(c) is the top view after position transformation.

[0055] Fig. 8 is a schematic diagram of the processing procedure of the shaft hole of the knotter support knotting nozzle, wherein Fig. 8(a) is the front view after coordinate transformation, Fig. 8(b) is the side view after position transformation, and Fig. 8(c) is the top view after position transformation.

[0056] Figure 9 Fig. 9 is a schematic diagram of the processing procedure of the cylindrical cam surface of the knotter support knotting nozzle.

[0057] Fig. 10 is a schematic diagram of the processing procedure of the shaft hole of the knotter support worm shaft, wherein Fig. 10(a) is the front view after coordinate transformation, Fig. 10(b) is the side view after position transformation, and Fig. 10(c) is the top view after position transformation.

[0058] In the figure: 1, four-axis clamp mounting plate; 2, fixed base plate; 3, cylindrical support; 4, rotary bearing; 5, fixed positioning base; 6, rotating positioning base; 7, positioning pin shaft; 8, clamp support positioning block; 9, support wedge-shaped pressing plate; 10, support cylindrical pressing plate; 11, main shaft hole anti-deflection positioning block; 12, clamp positioning stepped shaft; 13, main shaft hole concentric positioning block; 14, three-axis clamp mounting plate; 15, three-axis clamp positioning mandrel; 16, three-axis clamp pressing block; 17, three-axis clamp pressing plate support shaft; 18, three-axis clamp positioning block. DETAILED DESCRIPTION

[0059] Embodiments of the present application are described in detail below with reference to the attached drawings, which show examples of the embodiments. The embodiments described below are examples and are intended to explain the present application, and should not be understood as limiting the present application.

[0060] In the description of the present application, it is to be understood by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "front", "back", "left", "right", "up", "down", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and not indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0061] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0062] Embodiment 1

[0063] Figure 1 And Figure 3 A preferred embodiment of the special fixture for numerical control machining of the knotter support space structure is shown, including a three-axis machine tool fixture and a four-axis machine tool fixture;

[0064] The three-axis machine tool fixture is used to be mounted on a three-axis machine tool, and the knotter support is fully constrained when machining the lower end face counterbore and the end face of the main shaft hole;

[0065] The four-axis machine tool fixture is used to be mounted on a four-axis machine tool, and the knotter support is fully constrained when machining the cutter arm shaft hole, the rope clamping disc shaft hole, the knotter nozzle shaft hole, the cylindrical cam surface at the knotter nozzle, the worm shaft hole, and the upper end counterbore and the end face of the main shaft hole.

[0066] As shown in Figure 1 And Figure 2 As shown, Figure 1 is a three-axis machine tool fixture perspective view, Figure 2 (a) is a front view, Figure 2 (b) is a right view, Figure 2(c) is a top view, the three-axis machine tool clamp comprises a three-axis clamp mounting plate 14, a three-axis clamp positioning mandrel 15, a three-axis clamp pressing block 16, a three-axis clamp pressing plate support shaft 17 and a three-axis clamp positioning block 18;

[0067] The three-axis clamp positioning mandrel 15 is arranged on the three-axis clamp mounting plate 14 and is used for positioning in cooperation with the unprocessed main shaft hole of the knotter support; the three-axis clamp positioning mandrel 15 is a stepped shaft; the three-axis clamp pressing plate support shaft 17 is arranged on the three-axis clamp mounting plate 14 and the number is two; the three-axis clamp pressing block 16 is provided with a through hole at two ends, is connected with the top of the three-axis clamp mounting plate 14 through the through hole and is used for constraining the top of the knotter support; the three-axis clamp positioning block 18 is arranged on the three-axis clamp mounting plate 14 and is a wedge-shaped block; the wedge surface of the wedge-shaped block is attached to the inclined surface of the worm shaft hole of the knotter support.

[0068] According to the embodiment, preferably, the three-axis clamp mounting plate 14 is installed on the working platform of the three-axis numerical control machine tool; the three-axis clamp pressing block 16 and the three-axis clamp positioning block 18 are bolted on the three-axis clamp mounting plate 14; the three-axis clamp pressing plate support shaft 17 is screwed on the three-axis clamp mounting plate 14; and the three-axis clamp pressing block 16 is screwed on the three-axis clamp pressing plate support shaft 17.

[0069] The three-axis machine tool clamp is used for clamping the knotter support on the three-axis machine tool, and the machining of the lower end hole of the main shaft hole close to the side of the arm shaft hole and the end face thereof is completed on the three-axis numerical control machine tool, so that the lower end face of the main shaft hole has good parallelism with the end face of the second stepped shaft end of the stepped shaft, and the end face is used as a clamping reference datum surface of the four-axis machine tool clamp, thereby facilitating the machine tool operator to complete the first positioning, clamping and tool setting of the four-axis machine tool clamp on the four-axis numerical control machine tool.

[0070] As shown in Figure 4 and Figure 5 , the four-axis machine tool clamp comprises a four-axis clamp mounting plate 1, a fixed bottom plate 2, a cylindrical support 3, a rotary bearing 4, a fixed positioning base 5, a rotary positioning base 6, a positioning pin shaft 7, a support positioning block 8, a support wedge-shaped pressing plate 9, a support cylindrical pressing plate 10, a main shaft hole anti-deflection positioning block 11, a positioning stepped shaft 12 and a main shaft hole concentric positioning block 13.

[0071] The four-axis clamp mounting plate 1 is arranged on both sides of the fixed base plate 2; the fixed positioning base 5 is arranged on the fixed base plate 2; the rotary bearing 4 is arranged on the fixed positioning base 5; the rotary positioning base 6 is arranged on the rotary bearing 4; the fixed positioning base 5 and the rotary positioning base 6 are provided with through holes, the positioning pin shaft 7 is used for positioning the rotary positioning base 6 through the through holes; in order to prevent the rotary base from deforming along the main axis direction due to force when the tool feeds, a cylindrical support 3 is arranged between the rotary positioning base 6 and the fixed base plate 2; the support positioning block 8, the main shaft hole anti-deflection positioning block 11 and the positioning stepped shaft 12 are arranged on the rotary positioning base 6; the support positioning block 8 and the main shaft hole anti-deflection positioning block 11 are matched and used for limiting the deflection of the knotter support in the circumferential direction of the main shaft hole and the radial displacement, so as to fully constrain the knotter support; the main shaft hole anti-deflection positioning block 11 is provided with a protrusion, the protrusion is provided with a bolt, and the bolt is matched with the positioning stepped shaft 12; the positioning stepped shaft 12 is used for cooperating with the main shaft hole of the knotter support for positioning; the main shaft hole concentric positioning block 13 is arranged on the top of the positioning stepped shaft 12 and is used for positioning the main shaft hole axis of the knotter support and constraining the main shaft axis direction of the knotter support; in order to make the constraint reliable and avoid the interference of the clamping device on the machining of each shaft hole and the movement of the tool, the support wedge-shaped pressing plate 9 is used to press the cavity above the warped bottom of the support, and the support cylindrical pressing plate 10 is arranged on the concave surface of the main shaft hole and the tool arm shaft hole, and the support rod with a double-headed bolt is connected with the rotary positioning base.

[0072] According to the embodiment, preferably, the four-axis clamp mounting plate 1 is fixed on the workbench of the four-axis numerical control machine tool through bolts, the fixed base plate 2 is connected with the four-axis clamp mounting plate 1 through bolts, the rotary positioning base 7 and the fixed positioning base 6 are respectively connected with the inner and outer rings of the rotary bearing 4 through bolts, the clamp support positioning block 8 and the main shaft anti-deflection positioning block 11 are installed on the rotary positioning base 6 through bolts, the clamp positioning stepped shaft 12 is installed on the rotary positioning base 6 through bolts, and the main shaft hole concentric positioning block is installed on the clamp positioning stepped shaft 12 through bolts.

[0073] According to the embodiment, preferably, the rotary positioning base 6 and the fixed positioning base 5 are respectively installed on the inner and outer rings of the rotary bearing 4, high-precision positioning holes are machined on each base according to the machining design requirements, after the rotary positioning base 6 is rotated to the specified position, the positioning pin shaft 7 is used to connect the rotary positioning base 6 with the fixed positioning base 5 for positioning. And four groups of eight bolt holes are machined on the fixed base plate 2, when the rotary positioning base 6 drives the cylindrical support 3 to rotate to the specified bolt hole position, the cylindrical support 3 is connected with the fixed base plate 2 through bolts. After being connected, the cylindrical support can reduce the deformation of the rotary positioning base along the positioning stepped shaft axis direction caused by the tool feeding, and correspondingly can reduce the stress of the rotary bearing, thereby prolonging the service life of the rotary bearing.

[0074] In the use of four-axis machine tool clamps, the workpiece is first rotated by a certain angle around the four-axis machine tool rotation axis (A-axis), and then the workpiece is rotated by a certain angle around the clamp rotation axis (B-axis), and then positioned by the positioning pin shaft 7, so that the end face of the to-be-processed shaft hole is perpendicular to the tool shaft Z-axis. The tool is moved to the absolute center coordinates of the to-be-processed shaft hole, and the machining of each shaft hole and cylindrical cam surface is completed by feeding up and down along the Z-axis.

[0075] The four-axis machine tool clamp has a main shaft hole concentric positioning block 13 for ensuring the concentricity of the upper end counterbore of the main shaft hole and the lower end counterbore of the main shaft hole. The machined main shaft hole concentric positioning block 13 and the main shaft hole outer contour are equal in radius, the first stepped shaft surface of the clamp positioning stepped shaft 12 closely abuts the lower end counterbore surface of the main shaft hole, a threaded hole is machined at the center position of the shaft end of the clamp positioning stepped shaft 12, and the main shaft hole concentric positioning block is installed on the clamp positioning stepped shaft 12 through threaded connection, so that the main shaft hole axis and the main shaft hole concentric positioning block are coaxial. The axis center of the main shaft hole concentric positioning block 13 can be accurately measured by the four-point probe of the machine tool, and the absolute coordinate origin of the machine tool can be conveniently set.

[0076] According to the embodiment, preferably, the first stepped shaft of the three-axis clamp positioning mandrel 15 has a first stepped shaft cylindricity less than 0.01 mm, and the first stepped shaft has a coaxiality with the knotter support unprocessed main shaft less than 0.025 mm; the second stepped shaft end surface has a parallelism with the mounting plate less than 0.04 mm.

[0077] The main shaft hole anti-deflection positioning block 11 is provided with a protrusion on the left side, the right side and the rear side, a threaded hole is arranged on the protrusion, a bolt is arranged in the threaded hole, and the top of the bolt abuts against the positioning stepped shaft 12.

[0078] Embodiment 2

[0079] A numerical control machining method of a knotter support space structure, comprising the following steps:

[0080] First, the knotter support is clamped by a three-axis machine tool clamp, the main shaft hole of the knotter support is machined as a reference hole, an absolute coordinate system is established, then the knotter support is clamped by a four-axis machine tool clamp, the coordinates of the corresponding machining positions are found according to the absolute coordinate system established by the three-axis machine tool, the coordinate system is transformed to move the to-be-processed positions to the machining stations, and the machining of the remaining positions is completed.

[0081] The rest of the shaft hole and cylindrical cam surface are processed, and the rotation of the bearing is compensated for the B-axis freedom of the four-axis numerical control machine tool in the four-axis machine tool fixture assembly. In the four-axis numerical control machining, the horizontal plane L is established by translating the bottom surface of the knotter support a certain distance upward, and the coordinate system is established by taking the intersection of the horizontal plane L and the axis of the main shaft hole of the knotter support as the origin O. During shaft hole processing, the workpiece is first rotated by a certain angle around the A-axis of the four-axis machine tool, then the workpiece is rotated by a certain angle around the B-axis of the fixture, and then the positioning pin shaft is positioned to make the end face of the shaft hole to be processed perpendicular to the tool shaft Z-axis. The tool is moved to the center coordinates of the shaft hole to be processed, and the machining of each shaft hole is completed by feeding up and down along the Z-axis.

[0082] According to the embodiment, preferably, the machining method comprises the following steps:

[0083] Step S1: three-axis machine tool clamping: clamping the three-axis machine tool fixture on the three-axis numerical control machine tool, and clamping the unprocessed knotter support on the three-axis machine tool fixture;

[0084] Step S2: three-axis machine tool tool setting: positioning the element with the outer contour of the knotter support main shaft after clamping in step S1 as the axis, measuring the axis position of the knotter support main shaft hole, setting it as the reference axis, establishing the absolute coordinate system and the absolute coordinate origin with the lower end surface of the knotter support main shaft hole as the reference plane and making the reference axis perpendicular to the reference plane; completing the tool setting according to the absolute coordinate system and the absolute coordinate origin;

[0085] According to the embodiment, preferably, the outer contour of the knotter support main shaft hole is measured by a dial indicator, the position of the knotter support main shaft hole axis is determined, the main shaft is taken as the reference axis of the three-axis machine tool, the upper surface of the machining platform by a certain distance (L1=140mm) is taken as the reference plane of the lower end surface of the knotter support main shaft hole, the intersection of the reference axis and the reference plane is taken as the coordinate origin of the absolute coordinate system of the machine tool, and the absolute coordinate system of the three-axis numerical control machine tool is established.

[0086] Step S3: three-axis machine tool processing: using a three-axis machine tool boring tool to complete the processing of the lower end surface counterbore and the end surface of the knotter support main shaft hole after clamping in step S1;

[0087] Step S4: four-axis machine tool clamping: clamping the four-axis machine tool fixture on the four-axis numerical control machine tool, and clamping the knotter support processed in step S3 on the four-axis machine tool fixture;

[0088] Step S5: four-axis machine tool tool setting: taking the lower end face of the knotter support main shaft hole processed in step S3 as the reference plane, positioning the original piece with the main shaft hole concentric positioning block as the axis, determining the main shaft hole axis as the reference axis, taking the intersection of the reference plane and the reference axis as the workpiece coordinate origin to establish the four-axis NC machine tool coordinate system, tool setting is performed, and the positions of the shaft hole centers and the shaft line angles of the knife arm shaft hole, the knotter nozzle shaft hole, the worm shaft hole, and the rope clamp disc shaft hole in the absolute coordinate system are determined according to the four-axis NC machine tool absolute coordinate system;

[0089] According to the embodiment, preferably, in the four-axis NC machine tool, the lower end face of the knotter support main shaft hole is taken as the reference plane, the axis of the main shaft hole is taken as the reference axis, the intersection of the reference plane and the main shaft hole axis is taken as the coordinate origin O0, and the coordinate system of the workpiece is established. Meanwhile, it is set as the coordinate origin O of the absolute coordinate of the machine tool after clamping. According to the positional relationship of the shaft holes in the workpiece coordinate, the initial absolute coordinate center O1 of the knife arm shaft hole is determined as (-19.5, -58, 30), the initial absolute coordinate center O2 of the rope clamp disc shaft hole is determined as (56.14, -158.29, 51), the initial absolute coordinate center of the knotter nozzle shaft hole is determined as O3 (0, -137.64, 14.87), and the initial absolute coordinate center O4 of the worm shaft hole is determined as (80.27, -139.03, 88.17).

[0090] Step S6: four-axis machine tool processing: the knife arm shaft hole, the rope clamp disc shaft hole, the knotter nozzle shaft hole, the cylindrical cam surface at the knotter nozzle, and the worm shaft hole are processed in sequence. When the above positions are processed, the four-axis NC machine tool processing platform is rotated according to the position of the shaft hole to be processed, so that the absolute coordinate system of the four-axis NC machine tool is changed into the coordinate system of the shaft hole to be processed. The shaft hole or the surface to be processed reaches the processing station, and then processing is performed. The coordinate system of the cylindrical cam surface at the knotter nozzle is the same as that of the knotter nozzle shaft hole. After the above processing is completed, the main shaft hole concentric positioning block 13 is removed, and the processing of the upper end counterbore and the end face of the main shaft hole is completed.

[0091] The change from the absolute coordinate system of the four-axis NC machine tool to the coordinate system of the shaft hole to be processed in step S6 needs to be rotated around the A-axis, i.e. the Y-axis of the four-axis NC machine tool, and the B-axis, i.e. the Z-axis of the four-axis NC machine tool, and the coordinate transformation matrix is:

[0092] T=T A T Β

[0093] In the formula, T A is the transformation matrix of rotation around the A-axis, T Β is the transformation matrix of rotation around the B-axis, and i is the processing sequence.

[0094]

[0095]

[0096] wherein θ is the angle of rotation about the A-axis and β is the angle of alignment about the B-axis.

[0097] Further, the position D of the center of the shaft hole to be machined after coordinate system transformation in the absolute coordinate system of the four-axis NC machine tool in step S6 i (i = 1, 2, 3, 4) are:

[0098]

[0099] wherein x i ', y i ', z i ' are the positions of the center of the shaft hole to be machined after transformation in the absolute coordinate system of the four-axis NC machine tool, x i , y i , z i are the positions of the center of the shaft hole to be machined before transformation in the absolute coordinate system of the four-axis NC machine tool.

[0100] In the clamping and positioning process of the machine tool, the edge finder is used to determine the main axis corresponding to the outer contour of the shaft hole of the support in a four-point positioning manner, so as to determine the machining reference axis. Since the blank of the knotter casting has casting errors, the outer contour of the shaft hole of the corresponding support is not an ideal circle, and the geometric reference point of the shaft hole is also not an ideal reference point. Therefore, it is necessary to adjust the machining coordinates of each shaft hole of the support to compensate for the casting errors of the knotter support, so that the actual machining center position is as close as possible to the theoretical position, thereby ensuring the accuracy of machining, so that the five main shaft holes of the knotter support and the knotter nozzle cam surface have accurate spatial positional relationship, facilitating the installation of the subsequent knotter parts.

[0101] Generally, A1, A2, A3, A4 and A4 support castings are randomly selected in the same batch of castings, and the error value between the support blank reference point and the theoretical reference point is measured by the edge finder as Δx i Δy i Δz i , and then the average value of the error value in each direction is obtained. Denote the average value of the deviation of the measured blank initial coordinate system origin and the ideal coordinate system origin in each direction as (Δx, Δy, Δz), and then the corrected machining coordinates can be calculated:

[0102]

[0103] so that the deviation distance of the center position of each shaft hole of the machined knotter support from the ideal position is less than ±1mm, and the spatial angular position error between the five shaft holes of the support is less than ±1°, then the corrected machine tool machining absolute coordinates of each shaft hole of the knotter support are (x i ' + Δx' y i ' + Δy' zi ' + Δz').

[0104] According to the present embodiment, preferably, when the four-axis machine tool is processed, the right-hand Cartesian coordinate system is followed, the clockwise rotation angle of the numerical control machine tool around the axis is set as a negative angle, and the counterclockwise rotation angle is set as a positive angle. The lower end surface of the main shaft hole is set as a reference surface, the main shaft hole axis is set as a reference axis, the intersection of the reference surface and the reference axis is set as the workpiece coordinate origin of the knotter support, and when the machine tool is set, the point is set as the absolute coordinate origin in the machine tool coordinate system. And according to the position of the axis center and the axis angle of the cutter arm shaft hole, the knotter shaft hole, the worm shaft hole, and the rope clamping disc shaft hole in the workpiece coordinate system, the initial absolute center position coordinates of each shaft hole of the knotter are determined with the machine tool absolute coordinate system origin as the reference.

[0105] As shown in FIG. 6, the cutter arm shaft hole is processed, FIG. 6(a) is the front view after coordinate transformation, FIG. 6(b) is the side view after position transformation, and FIG. 6(c) is the top view after position transformation: the four-axis numerical control machine tool processing platform rotates by a certain angle (i.e. θ1=-90°) around the A-axis, reaches the processing station of the cutter arm shaft hole, inserts the positioning pin shafts into the corresponding positioning holes of the rotating positioning base and the fixed positioning base respectively, realizes the positioning of the workpiece B-axis rotation direction, moves the cutter to the absolute coordinates (x1'+Δx1' y1'+Δy1' z1'+Δz1'), and completes the processing of the cutter arm shaft hole along the Z-axis up and down feed. Specifically, when processing the cutter arm shaft hole, the processing technology of rough processing with a reamer first and then fine processing with a boring cutter is adopted to obtain the specified diameter tolerance requirement of the cutter arm shaft hole;

[0106] As shown in FIG. 7, the rope clamping disc shaft hole is processed, wherein FIG. 7(a) is the front view after coordinate transformation, FIG. 7(b) is the side view after position transformation, and FIG. 7(c) is the top view after position transformation: the processing station of the cutter arm shaft hole in the last step is kept unchanged (i.e. θ2=-90°), the positioning pin shafts are pulled out, the workpiece is rotated as a whole around the B-axis, and rotated to the specified position (i.e. β2=-12°), the two positioning pin shafts are inserted into the corresponding positioning holes on the rotating positioning base and the fixed positioning base respectively again, the positioning of the workpiece B-axis rotation direction is realized, then the cutter is moved to the coordinates (x2'+Δx2' y2'+Δy2' z2'+Δz2'), and according to the processing procedure requirement of reaming first and then boring, the cutter completes the processing of the rope clamping disc shaft hole along the Z-axis up and down feed;

[0107] As shown in Fig. 8, the knotter nozzle shaft hole processing: keep the processing station of the last step of clamping rope disc shaft hole unchanged, first rotate the processing platform counterclockwise around the A axis by 8° (i.e. θ3=-82°), then repeat the above process of pulling out the positioning pin shaft, rotating the bracket around the B axis by a certain angle (i.e. β3=-90°), and then inserting the positioning pin shaft into the corresponding positioning hole again, so as to realize the positioning of the B axis rotation direction, and at the same time, move the cutter to (x3'+Δx3' y3'+Δy3' z3'+Δz3'), and complete the processing of the knotter nozzle shaft hole along the Z axis according to the process requirements;

[0108] As shown in Fig. 8, the knotter nozzle shaft hole processing: keep the processing station of the last step of clamping rope disc shaft hole unchanged, first rotate the processing platform counterclockwise around the A axis by 8° (i.e. θ3=-82°), then repeat the above process of pulling out the positioning pin shaft, rotating the bracket around the B axis by a certain angle (i.e. β3=-90°), and then inserting the positioning pin shaft into the corresponding positioning hole again, so as to realize the positioning of the B axis rotation direction, and at the same time, move the cutter to (x3'+Δx3' y3'+Δy3' z3'+Δz3'), and complete the processing of the knotter nozzle shaft hole along the Z axis according to the process requirements; Figure 9 As shown in Fig. 8, the knotter nozzle shaft hole processing: keep the processing station of the last step of clamping rope disc shaft hole unchanged, first rotate the processing platform counterclockwise around the A axis by 8° (i.e. θ3=-82°), then repeat the above process of pulling out the positioning pin shaft, rotating the bracket around the B axis by a certain angle (i.e. β3=-90°), and then inserting the positioning pin shaft into the corresponding positioning hole again, so as to realize the positioning of the B axis rotation direction, and at the same time, move the cutter to (x3'+Δx3' y3'+Δy3' z3'+Δz3'), and complete the processing of the knotter nozzle shaft hole along the Z axis according to the process requirements;

[0109] As shown in Fig. 8, the knotter nozzle shaft hole processing: keep the processing station of the last step of clamping rope disc shaft hole unchanged, first rotate the processing platform counterclockwise around the A axis by 8° (i.e. θ3=-82°), then repeat the above process of pulling out the positioning pin shaft, rotating the bracket around the B axis by a certain angle (i.e. β3=-90°), and then inserting the positioning pin shaft into the corresponding positioning hole again, so as to realize the positioning of the B axis rotation direction, and at the same time, move the cutter to (x3'+Δx3' y3'+Δy3' z3'+Δz3'), and complete the processing of the knotter nozzle shaft hole along the Z axis according to the process requirements;

[0110] The processing of the upper end of the main shaft hole: after the processing of the knotter bracket worm shaft hole is completed, the processing platform of the machine tool is restored to the horizontal position, that is, the processing platform is counterclockwise rotated around the A axis by 110°, at this time the main shaft hole axis is restored to the reference axis position. When setting the absolute coordinate origin of the machine tool, the axis of the main shaft hole concentric positioning block has been accurately measured by the four-point probe of the machine tool, and because the main shaft hole concentric block is connected with the stepped shaft through bolts, the coaxiality of the axis of the positioning block and the main shaft hole axis is ensured. Now the main shaft hole concentric positioning block is removed, the cutter is moved to the processing coordinates, and the boring process is used to complete the processing of the upper end of the main shaft hole and the end face.

[0111] The three-axis machine tool clamp of the present application can clamp the to-be-processed knotter support, process the spindle hole lower end face counterbore and its end face on the three-axis machine tool, the four-axis machine tool clamp can clamp the to-be-processed knotter support processed on the three-axis machine tool, and process the knife arm shaft hole, the rope clamping disc shaft hole, the knotting nozzle shaft hole, the cylindrical cam surface at the knotting nozzle, and the worm shaft hole. By first processing on the three-axis machine tool to establish an absolute coordinate system, and then transforming the coordinate system of the shaft hole on the four-axis machine tool for processing, the knotter support processing precision requirement can be met, the five-axis machine tool is replaced to process the knotter support, the processing cost is reduced, and the economic benefit is improved.

[0112] It should be understood that, although the present specification is described in terms of various embodiments, not every embodiment contains only one independent technical solution, and the specification is described in this way only for clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

[0113] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present application, and are not used to limit the protection scope of the present application, and equivalent embodiments or changes made without departing from the spirit of the present application should be included in the protection scope of the present application.

Claims

1. A special fixture for numerical control machining of a space structure of a knotter support, characterized in that, The three-axis machine tool clamp and the four-axis machine tool clamp are included. The three-axis machine tool clamp is used for full constraint of the knotter support during machining of the main shaft hole lower end face counterbore and the end face of the knotter support. The four-axis machine tool clamp is used for full constraint of the knotter support during machining of the knife arm shaft hole, the rope clamping disc shaft hole, the knotting nozzle shaft hole, the cylindrical cam surface at the knotting nozzle, the worm shaft hole and the main shaft hole upper end counterbore and the end face of the knotter support. The four-axis machine tool clamp includes a four-axis clamp mounting plate (1), a fixed bottom plate (2), a cylindrical support (3), a rotary bearing (4), a fixed positioning base (5), a rotary positioning base (6), a positioning pin shaft (7), a support positioning block (8), a support wedge-shaped pressing plate (9), a support cylindrical pressing plate (10), a main shaft hole anti-deflection positioning block (11), a positioning stepped shaft (12) and a main shaft hole concentric positioning block (13). The four-axis clamp mounting plate (1) is arranged at the bottom of the fixed bottom plate (2); the fixed positioning base (5) is arranged on the fixed bottom plate (2); the rotary bearing (4) is arranged on the fixed positioning base (5); the rotary positioning base (6) is arranged on the rotary bearing (4); the fixed positioning base (5) and the rotary positioning base (6) are provided with through holes, and the positioning pin shaft (7) is used for positioning the rotary positioning base (6) through the through holes; the cylindrical support (3) is arranged between the fixed bottom plate (2) and the rotary positioning base (6) and is used for supporting the rotary positioning base (6); the support positioning block (8), the main shaft hole anti-deflection positioning block (11) and the positioning stepped shaft (12) are arranged on the rotary positioning base (6); the support positioning block (8) and the main shaft hole anti-deflection positioning block (11) are matched and used for limiting deflection of the knotter support in the circumferential direction of the main shaft hole and displacement in the radial direction; the main shaft hole anti-deflection positioning block (11) is provided with a protrusion, the protrusion is provided with a bolt, and the bolt is matched with the positioning stepped shaft (12); the positioning stepped shaft (12) is used for positioning in cooperation with the main shaft hole of the knotter support; the main shaft hole concentric positioning block (13) is arranged at the top of the positioning stepped shaft (12) and is used for positioning the axis of the main shaft hole of the knotter support and constraining the main shaft hole axis direction of the knotter support; the support wedge-shaped pressing plate (9) is arranged on the rotary positioning base (6) and is used for constraining the cavity above the bottom of the knotter support; and the support cylindrical pressing plate (10) is arranged on the rotary positioning base (6) and is used for constraining the concave surface between the main shaft hole and the knife arm shaft hole of the knotter support.

2. The special fixture for numerical control machining of the knotted support spatial structure according to claim 1, characterized in that, The three-axis machine tool clamp includes a three-axis clamp mounting plate (14), a three-axis clamp positioning spindle (15), a three-axis clamp pressing block (16), a three-axis clamp pressing plate support shaft (17) and a three-axis clamp positioning block (18). The three-axis clamp positioning spindle (15) is arranged on the three-axis clamp mounting plate (14) and is used for positioning in cooperation with the unprocessed main shaft hole of the knotter support; the three-axis clamp positioning spindle (15) is a stepped shaft; the three-axis clamp pressure plate support shaft (17) is arranged on the three-axis clamp mounting plate (14); the three-axis clamp pressing block (16) is arranged on the top of the three-axis clamp mounting plate (14) and is used for constraining the top of the knotter support; the three-axis clamp positioning block (18) is arranged on the three-axis clamp mounting plate (14); the three-axis clamp positioning block (18) is a wedge-shaped block; and the wedge surface of the three-axis clamp positioning block (18) is attached to the inclined surface of the worm shaft hole of the knotter support.

3. The special fixture for numerical control machining of the support spatial structure of the knotter according to claim 2, characterized in that, The first stepped shaft of the three-axis clamp positioning spindle (15) has a cylindricality less than 0.01 mm; and the coaxiality between the first stepped shaft and the unprocessed main shaft of the knotter support is less than 0.025 mm; and the parallelism between the end face of the second stepped shaft and the mounting plate is less than 0.04 mm.

4. A machining method using the special fixture for numerical control machining of the space structure of the knotter support according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: First, the three-axis machine tool clamp is used to clamp the knotter support, the main shaft hole of the knotter support is machined as a reference hole, and an absolute coordinate system is established; then, the four-axis machine tool clamp is used to clamp the knotter support, the coordinate of the corresponding machining position is found according to the absolute coordinate system established by the three-axis machine tool, the coordinate system is transformed, and the machining position is moved to the machining station, so that the machining of the knife arm shaft hole, the rope clamping disc shaft hole, the knotting nozzle shaft hole, the cylindrical cam surface at the knotting nozzle, the worm shaft hole and the upper end hole and the end face of the main shaft hole is completed.

5. The method according to claim 4, wherein the method is characterized by, The method comprises the following steps: Step S1: three-axis machine tool clamping: the three-axis machine tool clamp is clamped on the three-axis numerical control machine tool, and the unprocessed knotter support is clamped on the three-axis machine tool clamp; Step S2: three-axis machine tool tool setting: the outer contour of the main shaft hole of the knotter support clamped in step S1 is used as the axis positioning element, the axis position of the main shaft hole of the knotter support is measured, and is set as the reference axis; the absolute coordinate system and the absolute coordinate origin are established by taking the lower end face of the main shaft hole of the knotter support as the reference plane and making the reference axis perpendicular to the reference plane; and the tool setting is completed according to the absolute coordinate system and the absolute coordinate origin; Step S3: three-axis machine tool machining: the three-axis machine tool cutter is used to complete the machining of the lower end hole and the end face of the main shaft hole of the knotter support clamped in step S1; Step S4: four-axis machine tool clamping: the four-axis machine tool clamp is clamped on the four-axis numerical control machine tool, and the knotter support machined in step S3 is clamped on the four-axis machine tool clamp; Step S5: four-axis machine tool tool setting: the lower end face of the main shaft hole of the knotter support machined in step S3 is used as the reference surface, the main shaft hole concentric positioning block is used as the axis positioning element, the main shaft hole axis is determined as the reference axis, the intersection point of the reference surface and the reference axis is used as the workpiece coordinate origin to establish the four-axis numerical control machine tool coordinate system, the tool setting is performed, and the positions of the axis centers and the axis angles of the knife arm shaft hole, the knotting nozzle shaft hole, the worm shaft hole and the rope clamping disc shaft hole in the absolute coordinate system are determined according to the absolute coordinate system of the four-axis numerical control machine tool. Step S6: Four-axis machine tool processing: sequentially process the knife arm shaft hole, the rope clamping disc shaft hole, the knot nozzle shaft hole, the cylindrical cam surface at the knot nozzle and the worm shaft hole. When processing the above positions, rotate the four-axis numerical control machine tool processing platform according to the position of the shaft hole to be processed, so as to change from the four-axis numerical control machine tool absolute coordinate system to the coordinate system of the shaft hole to be processed; make the shaft hole or surface to be processed reach the processing station, and then process; the coordinate system of the cylindrical cam surface at the knot nozzle is the same as that of the knot nozzle shaft hole; after the above processing is completed, remove the main shaft hole concentric positioning block (13), and complete the processing of the main shaft hole upper end counterbore and the end face thereof.

6. The numerical control machining method of the knottier support space structure according to claim 5, characterized in that, The step S6 changes from the four-axis numerical control machine tool absolute coordinate system to the coordinate system of the shaft hole to be processed by rotating around the A-axis and the B-axis respectively, the A-axis being the Y-axis of the four-axis numerical control machine tool, and the B-axis being the Z-axis of the four-axis numerical control machine tool, and the coordinate transformation matrix is: ； wherein is the transformation matrix for rotation around the A axis, is the transformation matrix for rotation around the B axis, i is the machining order: ； ； Wherein, θ is the angle of rotation around the A-axis, and β is the angle of rotation around the B-axis.

7. The numerical control machining method of the knottier support space structure according to claim 6, characterized in that, Step S6 the position D of the center of the axis hole to be machined in the absolute coordinate system of the four-axis NC machine tool after coordinate system transformation i is: ； wherein, , , is the position of the center of the axis hole to be machined after the transformation in the absolute coordinate system of the four-axis NC machine tool, , , is the position of the center of the axis hole to be machined before the transformation in the absolute coordinate system of the four-axis NC machine tool.

8. The numerical control machining method of the knottier support space structure according to claim 5, characterized in that, The clamping and positioning process of machine tool processing adopts a feeler, and a four-point positioning mode is used to determine the main shaft line corresponding to the outer contour of the support shaft hole.

9. The numerical control machining method of the knottier support space structure according to claim 8, characterized in that, When determining the main axis corresponding to the outer contour of the support shaft hole, the machining coordinates of each shaft hole of the support need to be adjusted to compensate for the casting error of the knotter support; the error value between the reference point of the unprocessed knotter support and the theoretical reference point is measured by the edge finder , and then the average value of the error value in each direction is calculated; the average value of the deviation of the initial coordinate system origin of the blank and the ideal coordinate system origin in each direction is recorded as , and the corrected machining coordinates can be calculated. ； The absolute coordinate of each axis hole of the knotter support after the correction is .

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