A device and method for producing sub-head spun-dyed polyester pre-oriented yarn

Abstract

This invention belongs to the field of synthetic fiber technology and relates to a production apparatus and method for pre-oriented polyester yarn produced by sub-head spinning. The production apparatus includes, from top to bottom, a sand cup, a first diverter plate, a second diverter plate, and a spinneret. The first diverter plate has two symmetrically distributed first diverter holes, denoted as first diverter hole a' and first diverter hole b', respectively. The first and second diverter plates together form two independent semi-cylindrical cavities; the second diverter plate and the spinneret together form two independent semi-cylindrical cavities. Using the aforementioned production apparatus, the extrusion pressure of the first diverter holes a' and b' reaches 9-10 MPa during spinning. The production apparatus of this invention can ensure that the deviation in the overall yarn density of two bundles of yarn emerging from the same spinneret is less than 1%. The preparation method of this invention is simple, low-cost, and beneficial for improving spinning efficiency, making it suitable for large-scale industrial applications.

Description

Technical Field

[0001] This invention belongs to the field of synthetic fiber technology, specifically relating to a production apparatus and method for pre-oriented polyester yarn produced by sub-head spinning. Background Technology

[0002] The traditional production method for pre-oriented polyester yarn uses a "one spinneret, one bundle" model, meaning that only one bundle of yarn is spun from one spinneret. This model ensures high-quality yarn bundles but suffers from low output. Furthermore, many chemical fiber production companies determine the load, spinneret diameter, and other parameters for each spinning line during construction. To increase output, it is usually necessary to replace the entire system, from the melt piping to the winding equipment, which undoubtedly increases costs significantly.

[0003] To increase production, existing technologies have modified the spinneret by splitting it in two to produce two bundles of yarn, thus obtaining pre-oriented polyester yarn spun from a semi-tipped surface. The production process of pre-oriented polyester yarn spun from a semi-tipped surface involves polyester melt passing through a sand cup in the spinning assembly, flowing out from a small hole at the bottom of the sand cup, flowing to the spinneret, and then being ejected from the spinneret holes. The ejected yarn is split into two bundles, which are then oiled, guided, and wound into yarn cakes. For example, patent application CN109825886A discloses an energy-saving and efficiency-enhancing method for modifying the spinneret of a winding equipment. This method involves reconfiguring the spinneret, replacing it with an XF*2 spinneret, that is, doubling the number of spinneret holes on the original spinneret (i.e., improving the original XF to XF*2), and these spinneret holes are spaced apart on both sides.

[0004] However, this modification method also brought new problems. Due to the uneven flow rate of the melt in the filter sand, and the fact that this unevenness intensifies with the extended use of the spinning assembly, the melt distribution on the spinneret becomes uneven. Therefore, the amount of yarn produced from each exit orifice varies, and this variation is random and irregular. This ultimately leads to a deviation in the linear density of the two bundles of yarn produced from the same spinneret. According to the industry standard for polyester pre-oriented yarn (FZ / T 54033-2012), the linear density deviation rate for superior grade conventional polyester pre-oriented yarn is ±2.0%, while the linear density deviation rate for superior grade semi-twisted polyester pre-oriented yarn is relaxed to ±2.5%. However, with the increasing demands from downstream weaving users for higher linear density deviation rates between filaments, the existing semi-twisted polyester pre-oriented yarn can no longer meet market demands.

[0005] Therefore, it is particularly important to develop a production device and method for producing pre-oriented polyester yarn from the same spinneret that can reduce the deviation rate of linear density between two bundles of yarn produced by the same spinneret. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a production apparatus and method for pre-oriented polyester yarn.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A production apparatus for pre-oriented polyester yarn by sub-head spinning includes a sand cup and a spinneret. The spinneret holes on the spinneret are symmetrically distributed in two semi-circular regions, which are referred to as semi-circular region a and semi-circular region b, respectively. It also includes a first flow divider and a second flow divider.

[0009] The sand cup, the first flow divider plate, the second flow divider plate, and the spinneret are arranged in descending order. The sand cup and the first flow divider plate together form an inverted conical cavity, which is coaxial with the sand cup. The first flow divider plate and the second flow divider plate together form two independent semi-cylindrical cavities, denoted as semi-cylindrical cavity a* and semi-cylindrical cavity b*, respectively. The second flow divider plate and the spinneret together form two independent semi-cylindrical cavities, denoted as semi-cylindrical cavity a# and semi-cylindrical cavity b#, respectively.

[0010] The orthographic projections of semi-cylindrical cavity a*, semi-cylindrical cavity a#, and semi-circular region a completely overlap; the orthographic projections of semi-cylindrical cavity b*, semi-cylindrical cavity b#, and semi-circular region b completely overlap.

[0011] The first flow divider plate has two first flow divider holes symmetrically distributed on both sides of the central axis of the inverted conical cavity, which are respectively denoted as first flow divider hole a' and first flow divider hole b'. First flow divider hole a' connects the inverted conical cavity and the semi-cylindrical cavity a*, and first flow divider hole b' connects the inverted conical cavity and the semi-cylindrical cavity b*.

[0012] The outlet areas of the first split orifice a' and the first split orifice b' are the same, denoted as S1. The sum of the outlet areas of all spinnerets is denoted as S2. S2×60%≤S1≤S2×90%. This ensures that the extrusion pressure of the first split orifice a' and the first split orifice b' is greater than that of the spinnerets, thus ensuring that the flow rate of melt entering the first split orifice a' and the first split orifice b' is consistent.

[0013] The second diversion plate is provided with two sets of symmetrically distributed second diversion holes located above the semi-circular region a and the semi-circular region b, respectively.

[0014] After flowing out of the sand cup, the melt enters the inverted conical cavity. It is evenly divided through the first diversion hole a' and the first diversion hole b', and then reaches the semi-cylindrical cavities a* and b* respectively. After passing through the second diversion hole, it reaches the semi-cylindrical cavities a# and b# respectively, and then is ejected from the spinneret. The purpose of designing the second diversion hole on the second diversion plate is to disperse and guide the melt coming out of the first diversion hole of the first diversion plate. After dispersion and guidance, the melt can reach each spinneret hole of the spinneret plate evenly, so as not to result in uneven filament output from each spinneret hole. If there is no second diversion plate, although the two bundles of filaments coming out of the spinneret plate have a uniform overall density, the individual filaments will be uneven.

[0015] As a preferred technical solution:

[0016] As described above, in a pre-oriented polyester yarn production device, the sand cup is cylindrical, and the first diverter plate, the second diverter plate, and the spinneret are all circular plates. The axes of symmetry of the semicircular regions a and b intersect with the central axis of the spinneret, and the sand cup, the first diverter plate, the second diverter plate, and the spinneret are coaxial.

[0017] As described above, a production device for pre-oriented polyester yarn with a spun head has a melt distribution device inside the sand cup. The melt distribution device is used to change the flow direction of the melt entering the sand cup, so that the melt in different regions mixes with each other. The melt distribution device consists of a frustum and three blades installed on the frustum. The frustum is coaxial with the sand cup and the diameter of its large end face is smaller than the inner diameter of the sand cup. The large end face of the frustum is located below the small end face. The frustum is divided into upper and lower sections, and the three blades are all located in the upper section of the frustum.

[0018] As described above, the production device for pre-oriented polyester yarn by sub-head spinning has an outer diameter of 104-120mm, an inner diameter of 96-112mm, and a height of 69-70mm. The bottom of the sand cup has multiple through holes, all of which are distributed in concentric circles, each consisting of 5-6 circles. The diameter of the through holes is 1.5-2mm, and the distance between two adjacent through holes is 4-6mm.

[0019] The small end face diameter of the frustum is 8-10mm, the large end face diameter is 18-20mm, the height is 30-32mm, and the distance between the frustum and the bottom of the sand cup is 2.5-3mm.

[0020] The blades are inclined arc-shaped flat plates. The inner arc surface of the arc-shaped flat plates fits into the circumference of the frustum. The projections of the inner arc surfaces of the three arc-shaped flat plates onto the horizontal plane form a complete circle. The highest point of the inner arc surface of the arc-shaped flat plate is 8-10 mm from the top of the frustum, and the lowest point is 18-20 mm from the bottom of the frustum. The arc length of the inner arc surface of the arc-shaped flat plate is 10-12 mm, and the angle between the plane of the arc-shaped flat plate and the horizontal plane is 26-28°.

[0021] As described above, the production device for pre-oriented polyester yarn by sub-head spinning includes a sand cup with filter screen one, filter screen two, filter screen three, support screen one, support screen two, and support screen three. Filter screen one and filter screen two are both fitted onto the lower section of the truncated cone, with filter screen one located above filter screen two, and the two are spaced apart. When the melt passes through the metal sand, uneven pressure is likely to occur, but adding two layers of filter screens will make the pressure more uniform. Filter screen three, support screen one, support screen two, and support screen three are arranged from top to bottom at the bottom of the sand cup. The purpose of placing the three support screens is to prevent the high-pressure polyester melt from squeezing and deforming the filter screen when it passes through the high-mesh filter screen, thus affecting the filtration effect.

[0022] As described above, in a production device for pre-oriented polyester yarn, the vertical distance between filter screen two and the large end face of the truncated cone is 10mm, the distance between filter screen two and filter screen one is 10mm, the aperture of filter screen one and filter screen two is 60 mesh, the aperture of filter screen three is 600-800 mesh, the aperture of support screen one is 50 mesh, the aperture of support screen two is 20 mesh, and the aperture of support screen three is 10 mesh.

[0023] As described above, in a production apparatus for pre-oriented polyester yarn by sub-head spinning, the bottom surface of the sand cup is a plane m; the upper surface of the first diverter plate is provided with an inverted conical groove, and the lower surface is provided with a semi-circular groove a1 and a semi-circular groove b1; the upper surface of the second diverter plate is provided with a semi-circular groove a2 and a semi-circular groove b2, and the lower surface is provided with a semi-circular groove a3 and a semi-circular groove b3; the upper surface of the spinneret is a plane n.

[0024] Plane m and the inner surface of the inverted conical groove together form an inverted conical cavity; the inner surface of the semi-circular groove a1 and the inner surface of the semi-circular groove a2 together form a semi-cylindrical cavity a*, the inner surface of the semi-circular groove b1 and the inner surface of the semi-circular groove b2 together form a semi-cylindrical cavity b*; the semi-circular groove a3 and plane m together form a semi-cylindrical cavity a#, and the semi-circular groove b3 and plane m together form a semi-cylindrical cavity b#.

[0025] The upper surface of the second diverter plate is connected to the lower surface of the first diverter plate by pressure through an aluminum pad, and the lower surface of the second diverter plate is connected to the spinneret by pressure through an aluminum pad.

[0026] As described above, the production apparatus for pre-oriented polyester yarn using a sub-head spinning method has an inverted conical cavity shaped like an inverted frustum, with a large base diameter of 104-120 mm and a height of 15-18 mm. The angle between the generatrix and the large base is 18-20°. The upper ends of the first diversion holes a' and b' are both located on the small end of the inverted frustum. The heights of the semi-cylindrical cavities a* and b* are 2-4 mm. The total number of second diversion holes is 120-130, with a diameter of 1.4-1.6 mm, which helps to further distribute the pressure of the polyester melt evenly. The heights of the semi-cylindrical cavities a# and b# are 1.5-3 mm.

[0027] This invention also provides a method for producing pre-oriented polyester yarn with a sub-head spinning technique. The method employs a pre-oriented polyester yarn production apparatus as described in any of the preceding claims. During the spinning process, the pump output, S1, and S2 are adjusted to ensure that the extrusion pressure of the first diversion orifice a' and the first diversion orifice b' reaches 9-10 MPa. The melt flows through the sand cup into the inverted conical cavity between the sand cup and the first diversion plate, and is then extruded from the first diversion orifice a' and the first diversion orifice b'. During this process, the inverted conical cavity between the sand cup and the first diversion plate is filled with melt. Due to continuous feeding and discharging, the outlet area (S1) of the first diversion orifice a' and the first diversion orifice b' is small, resulting in a certain pressure on the melt within the inverted conical cavity. This pressure is called the extrusion pressure.

[0028] As a preferred technical solution:

[0029] As described above, in the production method of pre-oriented polyester yarn produced by a spinneret, the linear density deviation rate of two bundles of yarns from the same spinneret is less than 1.0%, the coefficient of variation (CV) of the linear density of the two bundles of yarns is less than 0.6%, the yarn unevenness of each bundle of yarns is less than 1.4%, and the diameter deviation rate of any two monofilaments from the same spinneret is less than 15%.

[0030] Beneficial effects:

[0031] (1) The preparation method of the present invention ingeniously utilizes a first flow divider to uniformly divide the melt into two parts, which are then introduced into two completely independent chambers. This design significantly improves the flow rate and pressure uniformity of the two flow dividers on the first flow divider. Then, through a dense network of small holes on the second flow divider, the melt flowing out of the flow dividers on the first flow divider is further finely dispersed and guided, ensuring that the melt can uniformly and stably reach each spinneret hole. This process makes the melt pressure and filament output of each spinneret hole more uniform and consistent, ultimately achieving an excellent effect where the linear density deviation rate of the two filament bundles produced by the same spinneret is less than 1.0%.

[0032] (2) The preparation method of the present invention does not require large-scale modification of the melt pipeline and winding equipment. It only requires the addition of a first filament splitting plate and a second filament splitting plate between the existing sand cup and spinneret. The operation is simple, the cost is low, and it is conducive to increasing the spinning output. It is suitable for large-scale industrial applications. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the production apparatus for pre-oriented polyester yarn in Embodiments 1-4 of the present invention;

[0034] Figure 2 yes Figure 1 A top view of the first splitter plate;

[0035] Figure 3 yes Figure 1 A bottom view of the first splitter plate;

[0036] Figure 4 yes Figure 3 The diagram shows a cross-sectional view of the first splitter plate along BB.

[0037] Figure 5 yes Figure 1 A top view of the second diverter plate;

[0038] Figure 6 yes Figure 1 A bottom view of the second diverter plate;

[0039] Figure 7 yes Figure 6 The diagram shows a cross-sectional view of the second flow divider along AA.

[0040] Figure 8 This is a schematic diagram of the melt distribution device according to embodiments 5-7 of the present invention;

[0041] Figure 9 These are schematic diagrams of the filter screen and support screen of Embodiments 8-10 of the present invention;

[0042] Among them, 1 is the sand cup, 2 is the first diverter plate, 3 is the second diverter plate, 4 is the spinneret plate, 5 is the metal sand, 6 is the frustum, 7 is the first filter screen, 8 is the second filter screen, 9 is the first diverter hole a', 10 is the first diverter hole b', 11 is the second diverter hole, 12 is the third filter screen, 13 is the first support mesh, 14 is the second support mesh, 15 is the third support mesh, 16 is the inverted conical cavity, 17 is the semi-cylindrical cavity a*, 18 is the semi-cylindrical cavity b*, 19 is the semi-cylindrical cavity a#, 20 is the semi-cylindrical cavity b#, 21 is the first blade, and 22 is the second blade. Detailed Implementation

[0043] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0044] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0045] (1) Linear density deviation rate of two bundles of filaments and coefficient of variation (CV) of linear density of two bundles of filaments: Two bundles of filaments from the same spinneret are denoted as filament 1 and filament 2 respectively. According to GB / T 14343-2008 "Test method for linear density of chemical fiber filaments", the mass of 10,000 meters of sample is determined, and the linear density (dtex) of filament 1 and the linear density (dtex) of filament 2 are calculated. The linear density deviation rate of two bundles of filaments is calculated according to the formula "linear density deviation rate of two bundles of filaments = |linear density of filament 1 - linear density of filament 2| / linear density of filament 1 × 100%". The coefficient of variation (CV) of linear density of two bundles of filaments is calculated according to the formula "linear density standard deviation / linear density average value".

[0046] (2) Evenness of each bundle of filaments: According to GB / T 14346-2015 "Test Method for Evenness of Chemical Fiber Filaments - Capacitive Method", the USTER5 evenness tester was used for testing. The specific process is as follows: First, the filament bundle is placed in an environment with a temperature of (20±2)℃ and a relative humidity of (65±5)% for 2 hours to adjust the humidity. Then, the filament bundle is passed through the two plates of the capacitor at a uniform speed. The mass in each equal interval is converted into an electrical signal. The percentage of the standard deviation of all test electrical signals to the average value is the evenness. The test speed is 200m / min and the filament bundle test time is 2.5min.

[0047] (3) Diameter deviation rate of any two monofilaments: According to FZ / T 50002-2013 "Test method for the irregularity of chemical fibers", the cross-section of the fiber is enlarged and the diameter of each monofilament is measured. The diameter deviation rate of any two monofilaments is calculated according to the formula "diameter deviation rate of two monofilaments = |diameter of monofilament 1 - diameter of monofilament 2| / diameter of monofilament 1 × 100%".

[0048] Example 1

[0049] like Figure 1The apparatus shown is for producing pre-oriented polyester yarn by spun yarn, comprising a sand cup 1, a first diverter plate 2, a second diverter plate 3, a spinneret 4, and metal sand 5; the sand cup 1, the first diverter plate 2, the second diverter plate 3, and the spinneret 4 are arranged sequentially from top to bottom; the upper surface of the second diverter plate 3 is pressurized to the lower surface of the first diverter plate 2 through an aluminum pad, and the lower surface of the second diverter plate 3 is pressurized to the spinneret 4 through an aluminum pad;

[0050] The sand cup 1 is cylindrical, and the first flow divider 2, the second flow divider 3, and the spinneret 4 are all circular plates; the sand cup 1, the first flow divider 2, the second flow divider 3, and the spinneret 4 are coaxial;

[0051] The bottom surface of the sand cup 1 is a plane m; the upper surface of the first diverter plate 2 is provided with an inverted conical groove, and the lower surface is provided with a semi-circular groove a1 and a semi-circular groove b1; the upper surface of the second diverter plate 3 is provided with a semi-circular groove a2 and a semi-circular groove b2, and the lower surface is provided with a semi-circular groove a3 and a semi-circular groove b3; the upper surface of the spinneret plate 4 is a plane n.

[0052] Plane m and the inner surface of the inverted conical groove together form an inverted conical cavity 16, which is coaxial with the sand cup 1; the inner surfaces of the semi-circular groove a1 and the semi-circular groove a2 together form a semi-cylindrical cavity a* 17, the inner surfaces of the semi-circular groove b1 and the semi-circular groove b2 together form a semi-cylindrical cavity b* 18; the semi-circular groove a3 and plane m together form a semi-cylindrical cavity a# 19, and the semi-circular groove b3 and plane m together form a semi-cylindrical cavity b# 20.

[0053] The spinneret 4 has circular spinneret holes that are symmetrically distributed in two semi-circular regions, which are denoted as semi-circular region a and semi-circular region b, respectively. The axes of symmetry of semi-circular region a and semi-circular region b intersect the central axis of spinneret 4.

[0054] The orthographic projections of semi-cylindrical cavities a* 17, a# 19 and semi-circular region a completely overlap; the orthographic projections of semi-cylindrical cavities b* 18, b# 20 and semi-circular region b completely overlap.

[0055] like Figure 1-4 The first flow divider plate 2 shown has two first flow divider holes symmetrically distributed on both sides of the central axis of the inverted conical cavity 16, denoted as first flow divider hole a' 9 and first flow divider hole b' 10, respectively. First flow divider hole a' 9 connects the inverted conical cavity 16 and the semi-cylindrical cavity a* 17, and first flow divider hole b' 10 connects the inverted conical cavity 16 and the semi-cylindrical cavity b* 18. The outlet areas of first flow divider hole a' 9 and first flow divider hole b' 10 are the same, denoted as S1, and the area of ​​S1 is 6.3 mm².2 The sum of the exit areas of all spinnerets is denoted as S2, and the area of ​​S2 is 10.5 mm. 2 S1 and S2 satisfy S1 = S2 × 60%;

[0056] The sand cup 1 has an outer diameter of 104 mm, an inner diameter of 96 mm, and a height of 69 mm. Multiple through holes are provided at the bottom of the sand cup 1, all arranged in concentric circles consisting of five circles. The diameter of each through hole is 1.5 mm, and the distance between two adjacent through holes is 4 mm. The inverted conical cavity 16 is shaped like an inverted frustum, with a large base diameter of 104 mm and a height of 15 mm. The angle between the generatrix and the large base is 18°. The upper ends of the first diversion holes a' 9 and b' 10 are both located at the small end of the inverted frustum. The heights of the semi-cylindrical cavities a* 17 and b* 18 are 2 mm. The heights of the semi-cylindrical cavities a# 19 and b# 20 are 1.5 mm.

[0057] like Figure 5-7 The second diversion plate 3 shown has two sets of symmetrically distributed second diversion holes 11 located above the semicircular region a and the semicircular region b, respectively; the total number of second diversion holes 11 is 120, and the hole diameter is 1.6mm.

[0058] A method for producing pre-oriented polyester yarn using a spinneret is disclosed. The method employs the aforementioned spinneret production apparatus. During the spinning process, the pump output is controlled at 106 g / min, ensuring that the extrusion pressure of the first diversion orifice a'9 and the first diversion orifice b'10 reaches 10 MPa. The linear density deviation rate between the two yarn bundles emerging from the same spinneret is 0.7%, the coefficient of variation (CV) of the linear density between the two yarn bundles is 0.29%, the maximum yarn evenness of each yarn bundle is 1.33%, and the maximum diameter deviation rate between any two filaments emerging from the same spinneret is 13.5%. No slurry leakage is observed at any of the 36 spinning positions over 24 hours.

[0059] Example 2

[0060] like Figure 1 The apparatus shown is for producing pre-oriented polyester yarn by spun yarn, comprising a sand cup 1, a first diverter plate 2, a second diverter plate 3, a spinneret 4, and metal sand 5; the sand cup 1, the first diverter plate 2, the second diverter plate 3, and the spinneret 4 are arranged sequentially from top to bottom; the upper surface of the second diverter plate 3 is pressurized to the lower surface of the first diverter plate 2 through an aluminum pad, and the lower surface of the second diverter plate 3 is pressurized to the spinneret 4 through an aluminum pad;

[0061] The sand cup 1 is cylindrical, and the first flow divider 2, the second flow divider 3, and the spinneret 4 are all circular plates; the sand cup 1, the first flow divider 2, the second flow divider 3, and the spinneret 4 are coaxial;

[0062] The bottom surface of the sand cup 1 is a plane m; the upper surface of the first diverter plate 2 is provided with an inverted conical groove, and the lower surface is provided with a semi-circular groove a1 and a semi-circular groove b1; the upper surface of the second diverter plate 3 is provided with a semi-circular groove a2 and a semi-circular groove b2, and the lower surface is provided with a semi-circular groove a3 and a semi-circular groove b3; the upper surface of the spinneret plate 4 is a plane n.

[0063] Plane m and the inner surface of the inverted conical groove together form an inverted conical cavity 16, which is coaxial with the sand cup 1; the inner surfaces of the semi-circular groove a1 and the semi-circular groove a2 together form a semi-cylindrical cavity a* 17, the inner surfaces of the semi-circular groove b1 and the semi-circular groove b2 together form a semi-cylindrical cavity b* 18; the semi-circular groove a3 and plane m together form a semi-cylindrical cavity a# 19, and the semi-circular groove b3 and plane m together form a semi-cylindrical cavity b# 20.

[0064] The spinneret 4 has circular spinneret holes that are symmetrically distributed in two semi-circular regions, which are denoted as semi-circular region a and semi-circular region b, respectively. The axes of symmetry of semi-circular region a and semi-circular region b intersect the central axis of spinneret 4.

[0065] The orthographic projections of semi-cylindrical cavities a* 17, a# 19 and semi-circular region a completely overlap; the orthographic projections of semi-cylindrical cavities b* 18, b# 20 and semi-circular region b completely overlap.

[0066] like Figure 1-4 The first flow divider plate 2 shown has two first flow divider holes symmetrically distributed on both sides of the central axis of the inverted conical cavity 16, denoted as first flow divider hole a' 9 and first flow divider hole b' 10, respectively. First flow divider hole a' 9 connects the inverted conical cavity 16 and the semi-cylindrical cavity a* 17, and first flow divider hole b' 10 connects the inverted conical cavity 16 and the semi-cylindrical cavity b* 18. The outlet areas of first flow divider hole a' 9 and first flow divider hole b' 10 are the same, denoted as S1, and the area of ​​S1 is 6.16 mm². 2 The sum of the exit areas of all spinnerets is denoted as S2, and the area of ​​S2 is 8.8 mm. 2 S1 and S2 satisfy S1 = S2 × 70%;

[0067] The sand cup 1 has an outer diameter of 105mm, an inner diameter of 97mm, and a height of 69.5mm. Multiple through holes are located at the bottom of the sand cup 1, all arranged in concentric circles consisting of six individual circles. The diameter of each through hole is 1.8mm, and the distance between two adjacent through holes is 5mm. The inverted conical cavity 16 is shaped like an inverted frustum, with a large base diameter of 105mm and a height of 15.5mm. The angle between the generatrix and the large base is 19°. The upper ends of the first diversion holes a' 9 and b' 10 are both located at the small end of the inverted frustum. The heights of the semi-cylindrical cavities a* 17 and b* 18 are 2.5mm. The heights of the semi-cylindrical cavities a# 19 and b# 20 are 2mm.

[0068] like Figure 5-7 The second diversion plate 3 shown has two sets of symmetrically distributed second diversion holes 11 located above the semicircular region a and the semicircular region b, respectively; the total number of second diversion holes 11 is 123, and the hole diameter is 1.55mm.

[0069] A method for producing pre-oriented polyester yarn using a pre-oriented polyester yarn spinning device is disclosed. During the spinning process, the pump output is controlled at 98 g / min, resulting in an extrusion pressure of 9.8 MPa at the first diversion orifice a' 9 and the first diversion orifice b' 10. The linear density deviation rate between the two yarn bundles from the same spinneret is 0.8%, the coefficient of variation (CV) of the linear density between the two yarn bundles is 0.43%, the maximum yarn evenness of each yarn bundle is 1.22%, and the maximum diameter deviation rate between any two filaments from the same spinneret is 13.4%. No slurry leakage is observed at any of the 36 spinning positions over 24 hours.

[0070] Example 3

[0071] like Figure 1 The apparatus shown is for producing pre-oriented polyester yarn by spun yarn, comprising a sand cup 1, a first diverter plate 2, a second diverter plate 3, a spinneret 4, and metal sand 5; the sand cup 1, the first diverter plate 2, the second diverter plate 3, and the spinneret 4 are arranged sequentially from top to bottom; the upper surface of the second diverter plate 3 is pressurized to the lower surface of the first diverter plate 2 through an aluminum pad, and the lower surface of the second diverter plate 3 is pressurized to the spinneret 4 through an aluminum pad;

[0072] The sand cup 1 is cylindrical, and the first flow divider 2, the second flow divider 3, and the spinneret 4 are all circular plates; the sand cup 1, the first flow divider 2, the second flow divider 3, and the spinneret 4 are coaxial;

[0073] The bottom surface of the sand cup 1 is a plane m; the upper surface of the first diverter plate 2 is provided with an inverted conical groove, and the lower surface is provided with a semi-circular groove a1 and a semi-circular groove b1; the upper surface of the second diverter plate 3 is provided with a semi-circular groove a2 and a semi-circular groove b2, and the lower surface is provided with a semi-circular groove a3 and a semi-circular groove b3; the upper surface of the spinneret plate 4 is a plane n.

[0074] Plane m and the inner surface of the inverted conical groove together form an inverted conical cavity 16, which is coaxial with the sand cup 1; the inner surfaces of the semi-circular groove a1 and the semi-circular groove a2 together form a semi-cylindrical cavity a* 17, the inner surfaces of the semi-circular groove b1 and the semi-circular groove b2 together form a semi-cylindrical cavity b* 18; the semi-circular groove a3 and plane m together form a semi-cylindrical cavity a# 19, and the semi-circular groove b3 and plane m together form a semi-cylindrical cavity b# 20.

[0075] The spinneret 4 has circular spinneret holes that are symmetrically distributed in two semi-circular regions, which are denoted as semi-circular region a and semi-circular region b, respectively. The axes of symmetry of semi-circular region a and semi-circular region b intersect the central axis of spinneret 4.

[0076] The orthographic projections of semi-cylindrical cavities a* 17, a# 19 and semi-circular region a completely overlap; the orthographic projections of semi-cylindrical cavities b* 18, b# 20 and semi-circular region b completely overlap.

[0077] like Figure 1-4 The first flow divider plate 2 shown has two first flow divider holes symmetrically distributed on both sides of the central axis of the inverted conical cavity 16, denoted as first flow divider hole a' 9 and first flow divider hole b' 10, respectively. First flow divider hole a' 9 connects the inverted conical cavity 16 and the semi-cylindrical cavity a* 17, and first flow divider hole b' 10 connects the inverted conical cavity 16 and the semi-cylindrical cavity b* 18. The outlet areas of first flow divider hole a' 9 and first flow divider hole b' 10 are the same, denoted as S1, and the area of ​​S1 is 5.52 mm². 2 The sum of the exit areas of all spinnerets is denoted as S2, and the area of ​​S2 is 6.9 mm. 2 S1 and S2 satisfy S1 = S2 × 80%;

[0078] The sand cup 1 has an outer diameter of 120mm, an inner diameter of 112mm, and a height of 70mm. Multiple through holes are located at the bottom of the sand cup 1, all arranged in concentric circles consisting of five circles. The diameter of each through hole is 2mm, and the distance between two adjacent through holes is 6mm. The inverted conical cavity 16 is shaped like an inverted frustum, with a large base diameter of 120mm and a height of 18mm. The angle between the generatrix and the large base is 20°. The upper ends of the first diversion holes a' 9 and b' 10 are located at the small end of the inverted frustum. The heights of the semi-cylindrical cavities a* 17 and b* 18 are 3mm. The heights of the semi-cylindrical cavities a# 19 and b# 20 are 2.5mm.

[0079] like Figure 5-7 The second diversion plate 3 shown has two sets of symmetrically distributed second diversion holes 11 located above the semicircular region a and the semicircular region b, respectively; the total number of second diversion holes 11 is 125, and the hole diameter is 1.5mm.

[0080] A method for producing pre-oriented polyester yarn using a spinneret is disclosed. The method employs the aforementioned spinneret production apparatus. During the spinning process, the pump output is controlled at 90 g / min, ensuring that the extrusion pressure of the first diversion orifice a' 9 and the first diversion orifice b' 10 reaches 9.5 MPa. The linear density deviation rate between the two yarn bundles emerging from the same spinneret is 0.8%, the coefficient of variation (CV) of the linear density between the two yarn bundles is 0.41%, the maximum yarn evenness of each yarn bundle is 1.36%, and the maximum diameter deviation rate between any two filaments emerging from the same spinneret is 14.7%. No slurry leakage is observed at any of the 36 spinning positions over 24 hours.

[0081] Example 4

[0082] like Figure 1 The apparatus shown is for producing pre-oriented polyester yarn by spun yarn, comprising a sand cup 1, a first diverter plate 2, a second diverter plate 3, a spinneret 4, and metal sand 5; the sand cup 1, the first diverter plate 2, the second diverter plate 3, and the spinneret 4 are arranged sequentially from top to bottom; the upper surface of the second diverter plate 3 is pressurized to the lower surface of the first diverter plate 2 through an aluminum pad, and the lower surface of the second diverter plate 3 is pressurized to the spinneret 4 through an aluminum pad;

[0083] The sand cup 1 is cylindrical, and the first flow divider 2, the second flow divider 3, and the spinneret 4 are all circular plates; the sand cup 1, the first flow divider 2, the second flow divider 3, and the spinneret 4 are coaxial;

[0084] The bottom surface of the sand cup 1 is a plane m; the upper surface of the first diverter plate 2 is provided with an inverted conical groove, and the lower surface is provided with a semi-circular groove a1 and a semi-circular groove b1; the upper surface of the second diverter plate 3 is provided with a semi-circular groove a2 and a semi-circular groove b2, and the lower surface is provided with a semi-circular groove a3 and a semi-circular groove b3; the upper surface of the spinneret plate 4 is a plane n.

[0085] Plane m and the inner surface of the inverted conical groove together form an inverted conical cavity 16, which is coaxial with the sand cup 1; the inner surfaces of the semi-circular groove a1 and the semi-circular groove a2 together form a semi-cylindrical cavity a* 17, the inner surfaces of the semi-circular groove b1 and the semi-circular groove b2 together form a semi-cylindrical cavity b* 18; the semi-circular groove a3 and plane m together form a semi-cylindrical cavity a# 19, and the semi-circular groove b3 and plane m together form a semi-cylindrical cavity b# 20.

[0086] The spinneret 4 has circular spinneret holes that are symmetrically distributed in two semi-circular regions, which are denoted as semi-circular region a and semi-circular region b, respectively. The axes of symmetry of semi-circular region a and semi-circular region b intersect the central axis of spinneret 4.

[0087] The orthographic projections of semi-cylindrical cavities a* 17, a# 19 and semi-circular region a completely overlap; the orthographic projections of semi-cylindrical cavities b* 18, b# 20 and semi-circular region b completely overlap.

[0088] like Figure 1-4 The first flow divider plate 2 shown has two first flow divider holes symmetrically distributed on both sides of the central axis of the inverted conical cavity 16, denoted as first flow divider hole a' 9 and first flow divider hole b' 10, respectively. First flow divider hole a' 9 connects the inverted conical cavity 16 and the semi-cylindrical cavity a* 17, and first flow divider hole b' 10 connects the inverted conical cavity 16 and the semi-cylindrical cavity b* 18. The outlet areas of first flow divider hole a' 9 and first flow divider hole b' 10 are the same, denoted as S1, and the area of ​​S1 is 4.68 mm². 2 The sum of the exit areas of all spinnerets is denoted as S2, and the area of ​​S2 is 5.2 mm. 2 S1 and S2 satisfy S1 = S2 × 90%;

[0089] The sand cup 1 has an outer diameter of 120mm, an inner diameter of 112mm, and a height of 70mm. Multiple through holes are located at the bottom of the sand cup 1, all arranged in concentric circles consisting of five circles. The diameter of each through hole is 2mm, and the distance between two adjacent through holes is 6mm. The inverted conical cavity 16 is shaped like an inverted frustum, with a large base diameter of 120mm and a height of 18mm. The angle between the generatrix and the large base is 20°. The upper ends of the first diversion holes a' 9 and b' 10 are located at the small end of the inverted frustum. The heights of the semi-cylindrical cavities a* 17 and b* 18 are 4mm. The heights of the semi-cylindrical cavities a# 19 and b# 20 are 3mm.

[0090] like Figure 5-7 The second diversion plate 3 shown has two sets of symmetrically distributed second diversion holes 11 located above the semicircular region a and the semicircular region b, respectively; the total number of second diversion holes 11 is 130, and the hole diameter is 1.4mm.

[0091] A method for producing pre-oriented polyester yarn using a pre-oriented polyester yarn spinning device is disclosed. During spinning, the pump output is 82 g / min, resulting in an extrusion pressure of 9.0 MPa at the first diversion orifice a' 9 and the first diversion orifice b' 10. The linear density deviation rate between two bundles of yarn from the same spinneret is 0.9%, the coefficient of variation (CV) of the linear density between the two bundles is 0.55%, the maximum evenness of each bundle is 1.29%, and the maximum diameter deviation rate between any two filaments from the same spinneret is 14.1%. No slurry leakage is observed at any of the 36 spinning positions over 24 hours.

[0092] Comparative Example 1

[0093] A production apparatus for pre-oriented polyester yarn with a sub-head spun pattern is basically the same as that in Example 1, except that the value of S1 is 6.3 mm. 2 The S2 value is 15.75 mm. 2 S1 = S2 × 40%.

[0094] A method for producing pre-oriented polyester yarn with a sub-head spinneret is basically the same as in Example 1, except that the spinning is carried out using the production device of Comparative Example 1.

[0095] Because the ratio of S1 to S2 is too small, it is easy to cause excessive pressure on the components, resulting in 18 instances of slurry leakage quality problems in 36 spinning positions within 24 hours.

[0096] Comparative Example 2

[0097] A production apparatus for pre-oriented polyester yarn with a sub-head spun pattern is basically the same as that in Example 1, except that the value of S1 is 6.3 mm. 2 The S2 value is 12.6 mm. 2S1 = S2 × 50%.

[0098] A method for producing pre-oriented polyester yarn with a serrated head is basically the same as in Example 1, except that the spinning is carried out using the production equipment of Comparative Example 2.

[0099] Because the ratio of S1 to S2 is too small, it can easily lead to excessive pressure on the components, resulting in 15 instances of grout leakage in 36 locations within 24 hours.

[0100] Comparative Example 3

[0101] A production apparatus for pre-oriented polyester yarn with a sub-head spun pattern is basically the same as that in Example 1, except that the value of S1 is 6.3 mm. 2 The S2 value is 6.63 mm. 2 S1 = S2 × 95%.

[0102] A method for producing pre-oriented polyester yarn with a serrated head is basically the same as in Example 1, except that the spinning is carried out using the production device of Comparative Example 3.

[0103] The linear density deviation rate of the two filament bundles from the same spinneret is 1.1%, the coefficient of variation (CV) of the linear density of the two filament bundles is 0.81%, the maximum unevenness of each filament bundle is 1.57%, and the maximum diameter deviation rate of any two filaments from the same spinneret is 20.6%.

[0104] Comparative Example 4

[0105] A production apparatus for pre-oriented polyester yarn with a sub-head spun pattern is basically the same as that in Example 1, except that the value of S1 is 6.3 mm. 2 S2 is 6.3mm. 2 S1 = S2 × 100%.

[0106] A method for producing pre-oriented polyester yarn with a serrated head is basically the same as in Example 1, except that the spinning is carried out using the production device of Comparative Example 4.

[0107] The linear density deviation rate of the two filament bundles from the same spinneret is 1.8%, the coefficient of variation (CV) of the linear density of the two filament bundles is 1.27%, the maximum unevenness of each filament bundle is 1.79%, and the maximum diameter deviation rate of any two filaments from the same spinneret is 30.1%.

[0108] Compared with Example 1, the linear density deviation rate, linear density variation coefficient (CV) value of the two filament bundles from the same spinneret in Comparative Examples 3 and 4 increased significantly. This is because S1 and S2 are the same size, and the first diversion hole a' and the first diversion hole b' failed to play a diversion role, which led to the increase in deviation.

[0109] Comparing Comparative Examples 1-4 and Examples 1-4, it can be seen that a ratio of S1 to S2 that is too large or too small is unfavorable. When the ratio is too small, multiple slurry leakage problems occurred in 36 spinning positions within 24 hours. When the ratio is too large, the linear density deviation rate of the two bundles of yarns increases, the coefficient of variation (CV) of the linear density of the two bundles of yarns increases, the evenness of each bundle of yarns increases, and the diameter deviation rate of any two monofilaments from the same spinneret increases.

[0110] Example 5

[0111] A production apparatus for pre-oriented polyester yarn with a serrated head differs from that in Example 1 in that: Figure 8 As shown, the sand cup 1 is also equipped with a melt distribution device. The melt distribution device is used to change the flow direction of the melt entering the sand cup 1, so that the melt in different regions mixes with each other. The melt distribution device consists of a frustum 6 and three blades installed on the frustum 6. The three blades are the first blade 21, the second blade 22, and the third blade (the third blade is in...). Figure 8 (Not shown), the frustum 6 is coaxial with the sand cup 1 and the diameter of the large end face is smaller than the inner diameter of the sand cup. The large end face of the frustum 6 is located below the small end face. The frustum 6 is divided into upper and lower sections, and the three blades are all located in the upper section of the frustum 6.

[0112] The small end face of the frustum 6 has a diameter of 8mm, the large end face has a diameter of 18mm, and the height is 30mm. The distance between the frustum 6 and the bottom of the sand cup 1 is 2.5mm.

[0113] The blades are inclined arc-shaped flat plates. The inner arc surface of the arc-shaped flat plates fits into the circumference of the frustum 6. The projections of the inner arc surfaces of the three arc-shaped flat plates onto the horizontal plane form a complete circle. The highest point of the inner arc surface of the arc-shaped flat plate is 8 mm from the upper end of the frustum 6, and the lowest point is 18 mm from the lower end of the frustum 6. The arc length of the inner arc surface of the arc-shaped flat plate is 10 mm, and the angle between the plane of the arc-shaped flat plate and the horizontal plane is 26°.

[0114] A method for producing pre-oriented polyester yarn using a spun yarn is basically the same as in Example 1, except that the spinning device of Example 5 is used. The linear density deviation rate of the two bundles of yarn from the same spinneret is 0.6%, the coefficient of variation (CV) of the linear density of the two bundles of yarn is 0.21%, the maximum unevenness of each bundle of yarn is 1.28%, the maximum diameter deviation rate of any two single filaments from the same spinneret is 13.9%, and there is no slurry leakage problem in 36 spinning positions for 24 hours.

[0115] Example 6

[0116] A production apparatus for pre-oriented polyester yarn with a serrated head differs from that in Example 1 in that: Figure 8As shown, the sand cup 1 is also equipped with a melt distribution device. The melt distribution device is used to change the flow direction of the melt entering the sand cup 1, so that the melt in different regions mixes with each other. The melt distribution device consists of a frustum 6 and three blades installed on the frustum 6. The three blades are the first blade 21, the second blade 22, and the third blade (the third blade is in...). Figure 8 (Not shown), the frustum 6 is coaxial with the sand cup 1 and the diameter of the large end face is smaller than the inner diameter of the sand cup. The large end face of the frustum 6 is located below the small end face. The frustum 6 is divided into upper and lower sections, and the three blades are all located in the upper section of the frustum 6.

[0117] The small end face diameter of the frustum 6 is 9mm, the large end face diameter is 19mm, the height is 31mm, and the distance between the frustum 6 and the bottom of the sand cup 1 is 3mm.

[0118] The blades are inclined arc-shaped flat plates. The inner arc surface of the arc-shaped flat plates fits into the circumference of the frustum 6. The projections of the inner arc surfaces of the three arc-shaped flat plates onto the horizontal plane form a complete circle. The highest point of the inner arc surface of the arc-shaped flat plate is 10mm from the top of the frustum 6, and the lowest point is 20mm from the bottom of the frustum 6. The arc length of the inner arc surface of the arc-shaped flat plate is 11mm, and the angle between the plane of the arc-shaped flat plate and the horizontal plane is 27°.

[0119] A method for producing pre-oriented polyester yarn using a spun yarn is basically the same as in Example 1, except that the spinning device of Example 6 is used. The linear density deviation rate of the two bundles of yarn from the same spinneret is 0.6%, the coefficient of variation (CV) of the linear density of the two bundles of yarn is 0.24%, the maximum unevenness of the yarn in each bundle is 1.17%, the maximum diameter deviation rate of any two filaments from the same spinneret is 12.5%, and there is no leakage problem in 36 spinning positions for 24 hours.

[0120] Example 7

[0121] A production apparatus for pre-oriented polyester yarn with a serrated head differs from that in Example 1 in that: Figure 8 As shown, the sand cup 1 is also equipped with a melt distribution device. The melt distribution device is used to change the flow direction of the melt entering the sand cup 1, so that the melt in different regions mixes with each other. The melt distribution device consists of a frustum 6 and three blades installed on the frustum 6. The three blades are the first blade 21, the second blade 22, and the third blade (the third blade is in...). Figure 8 (Not shown), the frustum 6 is coaxial with the sand cup 1 and the diameter of the large end face is smaller than the inner diameter of the sand cup. The large end face of the frustum 6 is located below the small end face. The frustum 6 is divided into upper and lower sections, and all three blades are located in the upper section of the frustum 6.

[0122] The small end face of the frustum 6 has a diameter of 10mm, the large end face has a diameter of 20mm, and the height is 32mm. The distance between the frustum 6 and the bottom of the sand cup 1 is 2.8mm.

[0123] The blades are inclined arc-shaped flat plates. The inner arc surface of the arc-shaped flat plates fits into the circumference of the frustum 6. The projections of the inner arc surfaces of the three arc-shaped flat plates onto the horizontal plane form a complete circle. The highest point of the inner arc surface of the arc-shaped flat plate is 9mm from the top of the frustum 6, and the lowest point is 19mm from the bottom of the frustum 6. The arc length of the inner arc surface of the arc-shaped flat plate is 12mm, and the angle between the plane of the arc-shaped flat plate and the horizontal plane is 28°.

[0124] A method for producing pre-oriented polyester yarn using a spun yarn is basically the same as in Example 1, except that the spinning device of Example 7 is used. The linear density deviation rate of the two bundles of yarn from the same spinneret is 0.6%, the coefficient of variation (CV) of the linear density of the two bundles of yarn is 0.26%, the maximum unevenness of the yarn in each bundle is 1.27%, the maximum diameter deviation rate of any two filaments from the same spinneret is 12.7%, and there is no leakage problem in 36 spinning positions for 24 hours.

[0125] In Examples 5-7, the linear density deviation rate of the two bundles of filaments from the same spinneret was 0.6%, the coefficient of variation (CV) of the linear density of the two bundles of filaments was 0.21-0.26%, the maximum unevenness of each bundle of filaments was 1.17-1.28%, the maximum diameter deviation rate of any two monofilaments from the same spinneret was 12.5-13.9%, and there was no slurry leakage problem in 36 spinning positions for 24 hours.

[0126] In Examples 5-7 and Example 1, the unevenness of each bundle of filaments from the same spinneret is less than 1.4%, and the diameter deviation rate of any two individual filaments from the same spinneret is less than 15%. However, in Examples 5-7, the linear density deviation rate of the two bundles of filaments from the same spinneret is even smaller, and the coefficient of variation (CV) of the linear density of the two bundles of filaments is also smaller. This indicates that the melt distribution device inside the sand cup is beneficial to reducing the linear density deviation rate of the two bundles of filaments from the same spinneret and the coefficient of variation (CV) of the linear density of the two bundles of filaments.

[0127] Example 8

[0128] A production apparatus for pre-oriented polyester yarn with a serrated head differs from that in Example 5 in that: Figure 9As shown, the sand cup 1 is also equipped with filter screen 7, filter screen 8, filter screen 12, support screen 13, support screen 24, and support screen 35. Filter screen 7 and filter screen 8 are both fitted onto the lower section of the frustum 6, with filter screen 7 located above filter screen 8 and the two are spaced apart. Filter screen 32, support screen 13, support screen 24, and support screen 35 are arranged from top to bottom at the bottom of the sand cup 1. The vertical distance between filter screen 28 and the large end face of the frustum 6 is 10mm, the distance between filter screen 28 and filter screen 7 is 10mm, the aperture of filter screen 7 and filter screen 28 is 60 mesh, the aperture of filter screen 312 is 800 mesh, the aperture of support screen 13 is 50 mesh, the aperture of support screen 214 is 20 mesh, and the aperture of support screen 315 is 10 mesh.

[0129] A method for producing pre-oriented polyester yarn with a serrated head is basically the same as in Example 1, except that the spinning is performed using the production apparatus of Example 8.

[0130] The linear density deviation rate of the two filament bundles from the same spinneret was 0.4%, the coefficient of variation (CV) of the linear density of the two filament bundles was 0.24%, the maximum unevenness of each filament bundle was CV value of 1.14%, the maximum diameter deviation rate of any two single filaments from the same spinneret was 12.6%, and there was no slurry leakage problem in 36 spinning positions for 24 hours.

[0131] Example 9

[0132] A production apparatus for pre-oriented polyester yarn with a serrated head differs from that in Example 5 in that: Figure 9 As shown, the sand cup 1 is also equipped with filter screen 7, filter screen 8, filter screen 12, support screen 13, support screen 24, and support screen 35. Filter screen 7 and filter screen 8 are both fitted onto the lower section of the frustum 6, with filter screen 7 located above filter screen 8 and the two are spaced apart. Filter screen 312, support screen 13, support screen 24, and support screen 315 are arranged from top to bottom at the bottom of the sand cup 1. The vertical distance between filter screen 28 and the large end face of the frustum 6 is 10mm, the distance between filter screen 28 and filter screen 7 is 10mm, the aperture of filter screen 7 and filter screen 28 is 60 mesh, the aperture of filter screen 312 is 700 mesh, the aperture of support screen 13 is 50 mesh, the aperture of support screen 214 is 20 mesh, and the aperture of support screen 315 is 10 mesh.

[0133] A method for producing pre-oriented polyester yarn with a serrated head is basically the same as in Example 1, except that the spinning is performed using the production apparatus of Example 9.

[0134] The linear density deviation rate of the two bundles of filaments from the same spinneret was 0.5%, the coefficient of variation (CV) of the linear density of the two bundles of filaments was 0.19%, the maximum unevenness of each bundle of filaments was 1.23%, the maximum diameter deviation rate of any two single filaments from the same spinneret was 11.8%, and there was no slurry leakage problem in 36 spinning positions for 24 hours.

[0135] Example 10

[0136] A production apparatus for pre-oriented polyester yarn with a serrated head differs from that in Example 5 in that: Figure 9 As shown, the sand cup 1 is also equipped with filter screen 7, filter screen 8, filter screen 12, support screen 13, support screen 24, and support screen 35. Filter screen 7 and filter screen 8 are both fitted onto the lower section of the frustum 6, with filter screen 7 located above filter screen 8 and the two arranged at intervals. Filter screen 312, support screen 13, support screen 24, and support screen 315 are arranged from top to bottom and placed at the bottom of the sand cup 1. The vertical distance between filter screen 28 and the large end face of the frustum 6 is 10mm, the distance between filter screen 28 and filter screen 7 is 10mm, the aperture of filter screen 7 and filter screen 28 is 60 mesh, the aperture of filter screen 312 is 600 mesh, the aperture of support screen 13 is 50 mesh, the aperture of support screen 214 is 20 mesh, and the aperture of support screen 315 is 10 mesh.

[0137] A method for producing pre-oriented polyester yarn with a serrated head is basically the same as in Example 1, except that the spinning is performed using the production apparatus of Example 10.

[0138] The linear density deviation rate of the two filament bundles from the same spinneret was 0.5%, the coefficient of variation (CV) of the linear density of the two filament bundles was 0.26%, the maximum unevenness of each filament bundle was 1.07%, the maximum diameter deviation rate of any two single filaments from the same spinneret was 12.5%, and there was no slurry leakage problem in 36 spinning positions for 24 hours.

[0139] In Examples 8-10, the linear density deviation rate of the two bundles of filaments from the same spinneret was 0.4-0.5%, the coefficient of variation (CV) of the linear density of the two bundles of filaments was 0.19-0.26%, the maximum unevenness of each bundle of filaments was 1.07-1.23%, the maximum diameter deviation rate of any two monofilaments from the same spinneret was 11.8-12.6%, and there was no slurry leakage problem in 36 spinning positions for 24 hours.

[0140] Comparing Examples 8-10 with Example 5, the unevenness of each bundle of filaments in Examples 8-10 and Example 5 is less than 1.4%, the diameter deviation rate of any two filaments from the same spinneret is less than 15%, and the coefficient of variation (CV) of the linear density of the two bundles of filaments is less than 0.6%. However, the linear density deviation rate of the two bundles of filaments from the same spinneret in Examples 8-10 is even smaller, indicating that the presence of three specific filter screens and three specific support screens inside the sand cup can further reduce the linear density deviation rate of the two bundles of filaments.

Claims

1. A production apparatus for pre-oriented polyester yarn using a semi-circular spinneret, comprising a sand cup and a spinneret, wherein the spinneret holes on the spinneret are symmetrically distributed in two semi-circular regions, denoted as semi-circular region a and semi-circular region b, characterized in that, It also includes a first splitter plate and a second splitter plate; The sand cup, the first flow divider plate, the second flow divider plate, and the spinneret are arranged in descending order. The sand cup and the first flow divider plate together form an inverted conical cavity, which is coaxial with the sand cup. The first flow divider plate and the second flow divider plate together form two independent semi-cylindrical cavities, denoted as semi-cylindrical cavity a* and semi-cylindrical cavity b*, respectively. The second flow divider plate and the spinneret together form two independent semi-cylindrical cavities, denoted as semi-cylindrical cavity a# and semi-cylindrical cavity b#, respectively. The orthographic projections of semi-cylindrical cavity a*, semi-cylindrical cavity a#, and semi-circular region a completely overlap; the orthographic projections of semi-cylindrical cavity b*, semi-cylindrical cavity b#, and semi-circular region b completely overlap. The first flow divider plate has two first flow divider holes symmetrically distributed on both sides of the central axis of the inverted conical cavity, which are respectively denoted as first flow divider hole a' and first flow divider hole b'. First flow divider hole a' connects the inverted conical cavity and the semi-cylindrical cavity a*, and first flow divider hole b' connects the inverted conical cavity and the semi-cylindrical cavity b*. The outlet areas of the first diverter orifice a' and the first diverter orifice b' are the same, denoted as S1. The sum of the outlet areas of all spinnerets is denoted as S2, where S2×60%≤S1≤S2×90%. The second diversion plate is provided with two sets of symmetrically distributed second diversion holes located above the semi-circular region a and the semi-circular region b, respectively. The sand cup is equipped with a melt distribution device, which is used to change the flow direction of the melt entering the sand cup so that the melt in different areas can be mixed with each other. The melt distribution device consists of a frustum and three blades installed on the frustum. The frustum is coaxial with the sand cup and the diameter of its large end face is smaller than the inner diameter of the sand cup. The large end face of the frustum is located below the small end face. The frustum is divided into upper and lower sections, and the three blades are all located in the upper section of the frustum. The outer diameter of the sand cup is 104-120mm, the inner diameter is 96-112mm, and the height is 69-70mm. The bottom of the sand cup has multiple through holes, all of which are distributed in concentric circles. Each concentric circle consists of 5-6 circles. The diameter of the through holes is 1.5-2mm, and the distance between two adjacent through holes is 4-6mm. The small end face diameter of the frustum is 8-10mm, the large end face diameter is 18-20mm, the height is 30-32mm, and the distance between the frustum and the bottom of the sand cup is 2.5-3mm. The blades are inclined arc-shaped flat plates. The inner arc surface of the arc-shaped flat plates fits into the circumference of the frustum. The projections of the inner arc surfaces of the three arc-shaped flat plates onto the horizontal plane form a complete circle. The highest point of the inner arc surface of the arc-shaped flat plate is 8-10 mm from the top of the frustum, and the lowest point is 18-20 mm from the bottom of the frustum. The arc length of the inner arc surface of the arc-shaped flat plate is 10-12 mm, and the angle between the plane of the arc-shaped flat plate and the horizontal plane is 26-28°.

2. The production apparatus for pre-oriented polyester yarn by sub-head spinning according to claim 1, characterized in that, The sand cup is cylindrical. The first flow divider, the second flow divider, and the spinneret are all circular plates. The axes of symmetry of the semicircular regions a and b intersect with the central axis of the spinneret. The sand cup, the first flow divider, the second flow divider, and the spinneret are coaxial.

3. The production apparatus for pre-oriented polyester yarn by sub-head spinning according to claim 1, characterized in that, The sand cup is also equipped with filter screen one, filter screen two, filter screen three, support screen one, support screen two, and support screen three. Filter screen one and filter screen two are both fitted on the lower section of the truncated cone, with filter screen one located above filter screen two, and the two are arranged at intervals. Filter screen three, support screen one, support screen two, and support screen three are arranged from top to bottom and placed at the bottom of the sand cup.

4. The production apparatus for pre-oriented polyester yarn by sub-head spinning according to claim 3, characterized in that, The vertical distance between filter screen 2 and the large end face of the truncated cone is 10mm. The distance between filter screen 2 and filter screen 1 is 10mm. The aperture of filter screen 1 and filter screen 2 is 60 mesh. The aperture of filter screen 3 is 600-800 mesh. The aperture of support mesh 1 is 50 mesh. The aperture of support mesh 2 is 20 mesh. The aperture of support mesh 3 is 10 mesh.

5. The production apparatus for pre-oriented polyester yarn according to claim 2, characterized in that, The bottom surface of the sand cup is a plane m; the upper surface of the first diverter plate is provided with an inverted conical groove, and the lower surface is provided with semi-circular grooves a1 and b1; the upper surface of the second diverter plate is provided with semi-circular grooves a2 and b2, and the lower surface is provided with semi-circular grooves a3 and b3; the upper surface of the spinneret is a plane n. Plane m and the inner surface of the inverted conical groove together form an inverted conical cavity; the inner surfaces of the semi-circular groove a1 and the semi-circular groove a2 together form a semi-cylindrical cavity a*, the inner surfaces of the semi-circular groove b1 and the semi-circular groove b2 together form a semi-cylindrical cavity b*; the semi-circular groove a3 and plane n together form a semi-cylindrical cavity a#, and the semi-circular groove b3 and plane n together form a semi-cylindrical cavity b#. The upper surface of the second diverter plate is connected to the lower surface of the first diverter plate by pressure through an aluminum pad, and the lower surface of the second diverter plate is connected to the spinneret by pressure through an aluminum pad.

6. The production apparatus for pre-oriented polyester yarn by sub-head spinning according to claim 1, characterized in that, The inverted conical cavity is shaped like an inverted frustum, with a diameter of 104-120 mm and a height of 15-18 mm on the large base. The angle between the generatrix and the large base is 18-20°. The upper ends of the first diversion holes a' and b' are both located on the small end of the inverted frustum. The heights of the semi-cylindrical cavities a* and b* are 2-4 mm. The total number of second diversion holes is 120-130, with a diameter of 1.4-1.6 mm. The heights of the semi-cylindrical cavities a# and b# are 1.5-3 mm.

7. A method for producing pre-oriented polyester yarn by sub-head spinning, characterized in that, Using the production apparatus for pre-oriented polyester yarn as described in any one of claims 1-6, during the spinning process, the extrusion pressure of the first diversion hole a' and the first diversion hole b' is made to reach 9-10 MPa by adjusting the pump output, S1, and S2.

8. The method for producing pre-oriented polyester yarn according to claim 7, characterized in that, The linear density deviation rate of two filament bundles from the same spinneret is less than 1.0%, the coefficient of variation (CV) of the linear density of the two filament bundles is less than 0.6%, the unevenness of each filament bundle is less than 1.4%, and the diameter deviation rate of any two filaments from the same spinneret is less than 15%.

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