Batten segmentation and combination process for improving stability of fermentation wooden barrel

Abstract

The invention relates to the technical field of baijiu brewing wooden barrel fermentation. According to the batten segmentation technology for improving the structural stability of the fermentation wooden barrel, logs are symmetrically segmented in the diameter direction and are subjected to chord cutting, battens with the inner planes and the outer planes parallel are formed, and part of arc surfaces are reserved to be used for forming arch-shaped mortise and tenon joints. The assembled wooden barrel is low in diameter change rate under the condition of 30%-90% RH, and the structure can be kept stable. The wood utilization rate is remarkably increased, leakage is effectively prevented, and the method is suitable for manufacturing large wooden barrels and has remarkable economic and social benefits.

Description

Technical Field

[0001] The invention relates to the technical field of wooden barrel fermentation for liquor brewing, and specifically proposes a wood strip splitting and combining process for improving the stability of a wooden barrel for fermentation. Background Art

[0002] In the field of baijiu brewing, to impart a distinctive aroma to the liquor and extract the beneficial functional components of the wood (such as geniposide from Eucommia ulmoides and flavonoids from Ginkgo biloba), more and more companies are using specialty woods such as oak, Eucommia ulmoides, Ginkgo biloba, and pine to make fermentation barrels. However, compared to mature stainless steel fermentation tanks, barrel technology is still in its early stages and presents the following prominent issues: Limited log diameter: Special wood with functional activity is often small-diameter logs, usually ≤130mm in diameter; and traditional wooden barrels require wall panels with a thickness of ≥50mm and a length of ≥800mm to ensure strength, resulting in an extremely low proportion of available logs and serious material waste.

[0003] Stress deformation and leakage: In the existing "quarter-sawn-tangential-tenon" process, in a brewing environment with a humidity of 30%-90% RH, the warping of the wood strips can reach 2-3mm, and the ovality of the barrel body is greater than 5%, which easily forms a penetrating leakage channel at the joints.

[0004] Scar treatment is costly: Traditional quarter-sawn / tangential-sawn processes expose scars directly to the wallboard surface, requiring manual repair or removal of the entire section. The scar repair time for a single barrel accounts for approximately 20%–25% of the total labor.

[0005] Low wood utilization rate: Taking a Eucommia log with a diameter of 120mm and a length of 900mm as an example, the yield rate of traditional technology is only about 42%; in addition, manual mortising, planing, repairing and other processes account for more than 35% of the total cost.

[0006] In summary, the industry urgently needs a barrel manufacturing process that can utilize small-diameter logs, inhibit moisture deformation, preserve knot integrity, improve wood utilization, and reduce labor costs. Summary of the Invention

[0007] In view of this, the present invention proposes a solution to the above-mentioned pain points and proposes a wood strip splitting and combination process to improve the stability of fermentation barrels.

[0008] The technical solution of the present invention is achieved as follows: The present invention provides a wood strip splitting and assembly process, comprising the following steps: 1. Splitting and chord cutting steps After splitting the log symmetrically along its diameter into two cylindrical halves, the outer arc surface of each half is then tangentially cut parallel to the diameter. This step creates two parallel inner and outer planes on each strip, while retaining partially arcuate surfaces on the left and right sides for the arched mortise and tenon joints. This ensures that the growth ring arcs of the two split halves are in opposite directions and mirror-imaged, paving the way for subsequent stress self-cancellation.

[0009] 2. Bow-shaped mortise and tenon design Bow-shaped mortise and tenon joints are provided along the length of the curved sides of the two wood strips. The cross-sectional profile of the tenon end face of the bow-shaped mortise and tenon joint is arc-shaped or straight, and the mortise groove matches the shape of the tenon. The mortise groove depth does not exceed one-third of the thickness of the wood strip. The curvature of the curved surface of the bow-shaped mortise and tenon matches the curved surface of the wood strip, ensuring a tight fit between the mortise and tenon. The tenon and mortise are continuous along the length of the wood strip, and the cross-sectional profile of the tenon complements the cross-sectional profile of the mortise. When the two are interlocked, they form a sliding fit along the length of the wood strip. The sliding tolerance (0.1mm-0.3mm) is used to absorb the expansion or contraction stress of the wood caused by changes in humidity.

[0010] 3. Assembly and stress compensation The two halves of the wood, fitted with bow-shaped mortise and tenon joints, are arranged in parallel, with the growth rings of adjacent wood strips oriented in opposite directions. These joints are then inserted and assembled into the barrel wall. A sliding tolerance of 0.1mm-0.3mm is allowed between the joints of adjacent wood strips to absorb the expansion and contraction stress caused by humidity fluctuations during use. This sliding tolerance, combined with the inverse alignment of the growth rings, ensures that the geometric angles of the assembled barrel do not vary by more than 5%.

[0011] The structure of the bow-shaped mortise and tenon Bow-shaped mortise and tenon is a special mortise and tenon structure, whose design is inspired by the natural arc surface of wood. Specifically: With the diameter section facing downward, along the axial perspective, one side of the arc surface includes, from top to bottom, a first tenon protrusion, a first mortise, a transition surface, a second tenon protrusion and a second mortise, wherein the first mortise, the transition surface and the second mortise are obtained by cutting.

[0012] Tenon (protrusion): A raised portion is machined onto the curved side of a wood strip, running the length of the strip. The cross-section of the raised end can be arc-shaped or straight. For an arc-shaped tenon, the cross-section of its end face is an arc, and the radius of curvature of this arc matches the curvature of the wood strip (naturally retained), ensuring a perfect fit between the tenon and the natural curve of the strip. For a trapezoidal tenon, the cross-section of its end face is a trapezoid, narrow at the top and wide at the bottom, making it easier to machine and assemble.

[0013] Mortise (recess): A complementary groove is machined into the corresponding curved side of the adjacent wood strip. Its shape and size exactly match the tenon, ensuring a tight fit within the mortise. The bottom surface of the mortise groove can be flat or curved, depending on the shape of the tenon. If the tenon is arc-shaped, the bottom surface of the mortise groove is also curved; if the tenon is trapezoidal, the bottom surface of the mortise groove is flat.

[0014] In order to cope with the expansion and contraction of wood under humidity changes, a sliding tolerance of 0.1mm-0.3mm is reserved between the arched mortise and tenon joints. Specifically: Longitudinal sliding tolerance: A gap of 0.1mm-0.3mm is reserved between the top of the tenon and the bottom of the mortise to allow a certain amount of sliding space in the longitudinal direction (i.e. the length of the wood strip).

[0015] Lateral sliding tolerance: A gap of 0.05mm-0.15mm is reserved between the sides of the tenon and the side walls of the mortise to allow a certain amount of sliding space for the tenon in the lateral direction (i.e. in the direction of the thickness of the wood strip).

[0016] Two-way sliding mechanism: This two-way sliding mechanism allows the wood strips to slide freely when the humidity changes, thereby absorbing expansion or contraction stress and preventing structural deformation and leakage due to stress concentration.

[0017] Because the growth rings of the wood strips are oriented in opposite directions after splitting, adjacent wood strips will deform in opposite directions when the humidity changes. The sliding tolerance design of the bow-shaped mortise and tenon joints allows these deformations to offset each other, significantly reducing the overall deformation of the barrel. The specific analysis is as follows: Offsetting radial deformation: When humidity increases, the wood strips will expand inward, and the radial deformation directions of adjacent wood strips are opposite. Through the sliding tolerance of the bow-shaped mortise and tenon joints, these deformations can offset each other and reduce the radial deformation of the barrel body.

[0018] Circumferential deformation offset: Similarly, circumferential deformation will be offset by the opposite deformation of adjacent wood strips, maintaining the geometric stability of the barrel.

[0019] The present invention has the following beneficial effects compared to the prior art: The present invention significantly improves the structural stability and service life of fermentation barrels through a unique process of wood strip splitting, tangential cutting and bow-shaped mortise and tenon joints, while significantly reducing production costs and increasing wood utilization. Specifically, under a typical brewing environment of 30%–90% RH and 20–30°C, the barrel was operated continuously for 12 months, and the barrel diameter change rate was strictly controlled within 0.5%, and there was no structural leakage visible to the naked eye. This achievement is due to the ingenious design of the bow-shaped mortise and tenon joints, the cross-sectional curvature of the end face of which precisely matches the curvature of the arc surface of the wood strips. In addition, the longitudinal sliding tolerance of 0.1–0.3mm and the lateral sliding tolerance of 0.05–0.15mm effectively absorb the expansion or contraction stress of the wood caused by humidity changes, ensuring that the geometric angle change of the barrel does not exceed 5%, and can maintain long-term stability. Furthermore, this process allows for the direct use of small-diameter specialty logs ranging from 80–130 mm in diameter, such as Eucommia ulmoides, Ginkgo biloba, and pine. This increases the yield from 42% with traditional methods to over 70%, reduces wood costs by over 28%, saves over 35% in labor hours, and reduces the overall cost per barrel by over 20%. The absence of metal contact with the barrel wall prevents the adverse effects of iron and copper ion precipitation on the wine's flavor, ensuring a pure and authentic wine. Furthermore, the same process can flexibly manufacture a range of fermentation barrels with diameters ranging from 500–1200 mm and heights from 800–1500 mm, meeting the needs of brewing at varying scales, including large-scale qu (Daqu), small-scale qu (Xiaoqu), and fruit wines, making it highly valuable for industry promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a cross-sectional view of a log segmentation according to the present invention; Figure 2 This is a cross-sectional view of the logs of the present invention after being split and spliced; Figure 3 This is a mortise and tenon cross-section of the log after splitting according to the present invention; Figure 4 This is a diagram of the split log and the mortise and tenon joints of the present invention; Figure 5 A cross-sectional view of the scar and the dividing line in the log of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] Unless otherwise specified, the methods used in the following examples are conventional methods. The materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, unless otherwise specified, and can be obtained commercially by those skilled in the art.

[0024] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range. In the present specification and claims, range definitions may be combined and / or interchanged, and if not otherwise stated, such ranges include all subranges contained therein.

[0025] The wood strip splitting and assembly process of the present invention is specifically as follows: 1. Reduce the permeability coefficient of wood: such as Figure 1 The log is split into two (equally divided in the diameter direction), and the arc curve of the cross-section growth ring is basically retained. This fully utilizes the principle that the early and late wood are relatively dense during the growth process of wood, reduces the wood permeability coefficient, and increases the service life of the wood. Small-diameter logs can also be used to make large barrel siding; 2. Simplify the process of scar treatment: Figure 5 Due to the inherent characteristics of wood, scars will grow as trees grow. The scars start from the core of the sapling and gradually grow with the tree rings. When the tree is cut radially or tangentially, the scars will be destroyed, making the scars directly exposed outside the wood strips. Without human intervention, there will be a risk of scar leakage. When the wood is split in two, there is no situation of destroying the scar (the entire scar is in the two halves of the wood). Therefore, this cutting combination can effectively prevent leakage caused by scars and ensure the stability of the overall structure of the wooden barrel.

[0026] 3. Use "bow tenon" to offset stress and reduce costs: ① For example Figure 2 、 Figure 3 、 Figure 4 As shown in the figure, the wood strips that are divided into two parts are made into a self-invented "bow-shaped tenon". This tenon is made along the arc surface of the wood strips, which retains the original material of the wood to the greatest extent (only the material at the mortise and tenon joints is removed), greatly reducing the loss of logs and improving the utilization rate of materials; ② After the wood strips that are divided into two parts are made into tenons, they are arranged and installed in a parallel form, so that the arc directions of the annual rings of the tangential wood strips on the adjacent barrel walls are opposite, and the potential stresses that cause the deformation of the wood offset each other, thereby reducing the leakage caused by the stress and deformation of the wood and maintaining the stability of the barrel structure to a greater extent; ③ As shown in the figure, the wood strips that are divided into two parts are made into tenons, which Figure 4 Symmetrical tenons are opened between adjacent wooden strips as shown, and a certain tolerance range is reserved for the mortise and tenon joints, with a maximum tolerance of no more than 0.3mm, so that the mortise and tenon curves are tightly connected and have a sliding margin. The geometric angle of the barrel assembly can vary by 5%. When the barrel is in use, the margin can effectively offset the stress caused by the expansion of the barrel and the pressure of the material on the outward expansion of the board.

[0027] Example 1 Preparation of Eucommia ulmoides Wood Fermentation Barrel (Process of the Invention) Log selection and processing Eucommia logs with a diameter of 120mm and a length of 900mm were selected. The logs were split symmetrically along their diameter into two cylindrical halves. The outer arc surface of each half was then cut parallel to the diameter, resulting in a 40mm thickness for each strip. The strips were then cut to form two parallel inner and outer planes, with arcs remaining on the left and right sides for the subsequent creation of bow-shaped mortise and tenon joints. The growth ring arcs of the two halves were oriented in opposite directions.

[0028] Bow-shaped mortise and tenon processing A bow-shaped mortise and tenon is created along the length of the curved side of the wood strip. The cross-sectional profile of the bow-shaped mortise and tenon is an arc, and the curvature radius of its end face cross-section is consistent with the curvature of the curved surface of the wood strip. The mortise and tenon depth is 13mm (no more than one-third of the thickness of the wood strip), and the surface roughness Ra is controlled within 6.3μm. The curvature radius tolerance of the mortise and tenon joint is ±0.05mm, ensuring a tight fit between the tenon and the mortise. A 0.2mm gap is reserved between the top of the convex tenon and the bottom of the concave tenon of the bow-shaped mortise and tenon, and a 0.1mm gap is reserved between the sides of the convex tenon and the side walls of the concave tenon to form a two-way sliding allowance.

[0029] Assembly and testing The processed wood strips are arranged in parallel, with the growth rings of adjacent strips oriented in opposite directions. They are then joined together using arched mortise and tenon joints to form the barrel wall. The assembled barrel has a diameter of 600mm and a height of 900mm. Under continuous operation for 12 months at 30%–90% relative humidity and 20°C–30°C, the barrel diameter changed by only 0.3%, far below the design standard of 0.5%, and no structural leakage was observed.

[0030] Comparative Example 1 Production of Eucommia wood fermentation barrels (traditional process) Log selection and processing Eucommia logs with a diameter of 120mm and a length of 900mm were selected. The logs were split symmetrically along their diameter into two cylindrical halves. The outer arc surface of each half was then cut parallel to the diameter, resulting in a 40mm thick strip. The strips were then cut to form two parallel inner and outer planes, with arcs remaining on the left and right sides for later straight tenoning. The growth ring arcs of the two halves were oriented in opposite directions.

[0031] Straight tenon processing Straight tenons are cut along the length of the curved side of the wood strips. They have a rectangular cross-section, a depth of 15mm (more than one-third of the wood strip thickness), and a surface roughness Ra of approximately 12.5μm. The curvature radius tolerance of the mortise and tenon joint is ±0.1mm, resulting in low machining precision and requiring manual trimming. Straight tenons lack a sliding tolerance design and are unable to absorb the expansion and contraction stresses of the wood caused by humidity fluctuations.

[0032] Assembly and testing The processed wood strips were arranged in parallel, with the growth rings of adjacent strips oriented in opposite directions. These strips were then joined together using straight tenons to form the barrel walls. The assembled barrels had a diameter of 600 mm and a height of 900 mm. After 12 months of continuous operation under conditions of 30%–90% relative humidity and 20°C–30°C, the barrel diameter changed by 1.2%, and multiple structural leaks were observed.

[0033] Comparative Analysis Cost comparison Traditional craft material costs: higher due to low wood utilization (42%) The material cost of the process of the present invention is relatively low due to the high utilization rate of wood (72%) Performance Comparison Traditional process: The barrel diameter change rate is 1.2%, and multiple structural leaks occur.

[0034] The process of the present invention: the barrel diameter change rate is only 0.3%, and there is no structural leakage.

[0035] Example 2 Preparation of Ginkgo Wood Fermentation Barrels (Process of the Invention) Log selection and processing Ginkgo logs with a diameter of 100mm and a length of 800mm were selected. The logs were split symmetrically along their diameter into two semi-cylinders. The outer arc surface of each semi-cylinder was then cut parallel to the diameter, resulting in a 35mm thickness for each strip. The strips were then cut to form two parallel planes, with the arc surfaces on the left and right sides retained for the subsequent creation of arched mortise and tenon joints. The arc directions of the growth rings of the two halves of the split strips were opposite to each other.

[0036] Bow mortise and tenon processing Bow-shaped mortise and tenon joints are created along the length of the curved side of the wood strip. The cross-sectional profile of the bow-shaped mortise and tenon joint is trapezoidal, with the end cross-section forming a trapezoidal structure that is narrow at the top and wide at the bottom. The mortise and tenon depth is 12mm (no more than one-third of the thickness of the wood strip), and the surface roughness Ra is controlled within 3.2μm. The curvature radius tolerance of the mortise and tenon joint surface is ±0.05mm, ensuring a tight fit between the tenon and the mortise. A 0.15mm gap is reserved between the top of the convex tenon and the bottom of the concave tenon of the bow-shaped mortise and tenon joint, and a 0.08mm gap is reserved between the sides of the convex tenon and the side walls of the concave tenon to create a two-way sliding allowance.

[0037] Assembly and testing The processed wood strips are arranged in parallel, with the growth rings of adjacent strips oriented in opposite directions. They are then joined together using arched mortise and tenon joints to form the barrel wall. The assembled barrel has a diameter of 500mm and a height of 800mm. Under continuous operation for 12 months at 30%–90% relative humidity and 20°C–30°C, the barrel diameter changed by only 0.4%, far below the design standard of 0.5%, and no structural leakage was observed.

[0038] Comparative Example 2 Making Ginkgo Wood Fermentation Barrels (Traditional Craftsmanship) Log selection and processing Ginkgo logs with a diameter of 100mm and a length of 800mm were selected. The logs were split symmetrically along their diameter into two semi-cylinders. The outer arc surface of each half was then cut parallel to the diameter, with each strip having a thickness of 35mm. The strips were cut to form two parallel inner and outer planes, with some arc surfaces retained on the left and right sides for subsequent straight tenoning. The arc directions of the growth rings of the two halves of the split strips were opposite to each other.

[0039] Straight tenon processing Straight tenons are cut along the length of the curved side of the wood strips. They have a rectangular cross-section, a depth of 15mm (more than one-third of the wood strip thickness), and a surface roughness Ra of approximately 12.5μm. The curvature radius tolerance of the mortise and tenon joint is ±0.1mm, resulting in low machining precision and requiring manual trimming. Straight tenons lack a sliding tolerance design and are unable to absorb the expansion and contraction stresses of the wood caused by humidity fluctuations.

[0040] Assembly and testing Processed wood strips were arranged in parallel, with the growth rings of adjacent strips oriented in opposite directions. These strips were then joined together using straight tenons to form the barrel walls. The assembled barrels had a diameter of 500 mm and a height of 800 mm. Under continuous operation for 12 months at 30%–90% relative humidity and 20°C–30°C, the barrel diameter changed by 1.0%, and multiple structural leaks were observed.

[0041] Total working hours Under traditional technology, it takes 10 hours to complete the above process.

[0042] Comparative Analysis Cost comparison Traditional craft material costs: higher due to low wood utilization (42%) The material cost of the process of the present invention is relatively low due to the high utilization rate of wood (75%) Performance Comparison Traditional process: The barrel diameter change rate is 1.0%, and multiple structural leaks occur.

[0043] The process of the present invention: the barrel diameter change rate is only 0.4%, and there is no structural leakage.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wood strip splitting and combining process for improving the stability of fermentation barrels, characterized in that: The following steps are involved: (1) After the log is symmetrically split into two half cylinders along its diameter, the outer arc surface of each half cylinder is tangentially cut along the direction parallel to the diameter surface, so that each wood strip forms two inner and outer parallel planes, retaining the complete arc side, which is used to form the bow-shaped mortise and tenon joints, and the annual ring arc directions of the two half wood strips thus obtained are opposite to each other; (2) A bow-shaped mortise and tenon is provided on the curved side of the two half wood strips along the length thereof, the cross-sectional profile of the tenon end of the bow-shaped mortise and tenon is an arc or a straight line, the cross-sectional profile of the bottom surface of the mortise groove corresponds to the cross-sectional profile of the tenon end, and the depth of the mortise groove does not exceed one-third of the thickness of the wood strip; (3) Arrange the two halves of the wood strips with the bow-shaped mortise and tenon joints in parallel so that the arc directions of the growth rings of adjacent wood strips are opposite to each other, and assemble them into the barrel wall by plugging them together through the bow-shaped mortise and tenon joints, wherein a sliding tolerance of 0.1mm-0.3mm is reserved between the bow-shaped mortise and tenon joints of adjacent wood strips to absorb the expansion or contraction stress of the wood caused by humidity changes during the use of the barrel; (4) Through the synergistic effect of the sliding tolerance and the reverse arrangement of the annual rings, the geometric angle variation of the assembled barrel does not exceed 5%.

2. The wood strip splitting and combining process for improving the stability of a fermentation barrel according to claim 1, characterized in that: The logs are selected from one or more of eucommia wood, ginkgo wood, and pine wood, and the log diameter does not exceed 130 mm.

3. The wood strip splitting and combining process for improving the stability of a fermentation barrel according to claim 1, characterized in that: The thickness of the wooden strips after symmetrical segmentation is 30 mm to 50 mm. Due to the symmetrical segmentation method, the scars on the core of the log are completely contained within the cross section of a single wooden strip, and no cut surface is exposed.

4. The wood strip splitting and combining process for improving the stability of a fermentation barrel according to claim 1, characterized in that: The bow-shaped mortise and tenon is formed by a CNC milling machine or laser cutting, and its surface roughness Ra is less than or equal to 6.3 μm, and the curvature radius tolerance of the mortise and tenon joint surface is ±0.05 mm.

5. The wood strip splitting and combining process for improving the stability of a fermentation barrel according to claim 1, characterized in that: The setting of the sliding tolerance is achieved in the following way: A gap of 0.1mm-0.3mm is reserved between the top of the convex tenon and the bottom of the concave mortise and tenon of the bow-shaped mortise and tenon, and a gap of 0.05mm-0.15mm is reserved between the two sides of the convex tenon and the side walls of the concave mortise and tenon to form a two-way sliding allowance.

6. The wood strip splitting and combining process for improving the stability of a fermentation barrel according to claim 1, characterized in that: After the assembly, the barrel diameter change rate is ≤0.5% under the condition of humidity change range of 30%-90%RH, and there is no structural leakage.

7. The wood strip splitting and combining process for improving the stability of a fermentation barrel according to claim 1, characterized in that: Compared with the traditional right-angle mortise and tenon barrel making process, the process increases wood utilization by more than 28%, reduces labor costs by more than 35%, and is suitable for the production of large wooden barrels with a diameter of ≥500mm.

8. A fermentation barrel made by the wood strip splitting and combining process for improving the stability of a fermentation barrel according to any one of claims 1 to 7, characterized in that: The barrel wall of the wooden barrel is composed of multiple wooden strips connected to each other through bow-shaped mortise and tenon joints, the annual ring arc directions of adjacent wooden strips are opposite, and the barrel body can maintain a stable structure during long-term use.

Images